An introduction to Mechanism design: Single Item...

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Mechanism design Auctions:Context and Definitions Single item auctions Analyzing auctions Revenue in auctions An introduction to Mechanism design: Single Item Auctions Maria Serna Fall 2017 AGT-MIRI Single item auctions

Transcript of An introduction to Mechanism design: Single Item...

Page 1: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

An introduction to Mechanism design:Single Item Auctions

Maria Serna

Fall 2017

AGT-MIRI Single item auctions

Page 2: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

1 Mechanism design

2 Auctions:Context and Definitions

3 Single item auctions

4 Analyzing auctions

5 Revenue in auctions

AGT-MIRI Single item auctions

Page 3: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Mechanism design

Players have hidden information and try to manipulate theworld

Mediator wants to avoid some type of social misbehavior

An example: resource sharing

How to split a pizza among two kids so that they do not envyeach other?

mediator has to design an algorithm (mechanism) to split thepizza and to allocate the two pieces.Ask one kid to split the pizza and let the other choose theportion

This mechanism provides an envy-free splitting

AGT-MIRI Single item auctions

Page 4: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Mechanism design

Players have hidden information and try to manipulate theworld

Mediator wants to avoid some type of social misbehavior

An example: resource sharing

How to split a pizza among two kids so that they do not envyeach other?

mediator has to design an algorithm (mechanism) to split thepizza and to allocate the two pieces.Ask one kid to split the pizza and let the other choose theportion

This mechanism provides an envy-free splitting

AGT-MIRI Single item auctions

Page 5: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Mechanism design

Players have hidden information and try to manipulate theworld

Mediator wants to avoid some type of social misbehavior

An example: resource sharing

How to split a pizza among two kids so that they do not envyeach other?

mediator has to design an algorithm (mechanism) to split thepizza and to allocate the two pieces.

Ask one kid to split the pizza and let the other choose theportion

This mechanism provides an envy-free splitting

AGT-MIRI Single item auctions

Page 6: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Mechanism design

Players have hidden information and try to manipulate theworld

Mediator wants to avoid some type of social misbehavior

An example: resource sharing

How to split a pizza among two kids so that they do not envyeach other?

mediator has to design an algorithm (mechanism) to split thepizza and to allocate the two pieces.Ask one kid to split the pizza and let the other choose theportion

This mechanism provides an envy-free splitting

AGT-MIRI Single item auctions

Page 7: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Mechanism design

Players have hidden information and try to manipulate theworld

Mediator wants to avoid some type of social misbehavior

An example: resource sharing

How to split a pizza among two kids so that they do not envyeach other?

mediator has to design an algorithm (mechanism) to split thepizza and to allocate the two pieces.Ask one kid to split the pizza and let the other choose theportion

This mechanism provides an envy-free splitting

AGT-MIRI Single item auctions

Page 8: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Mechanism design

One way to design mechanism combines prizing withallocations.

We will focus on the study of some auctions:How to sell items to potential buyers with private valuations.

Objective: truth-telling

AGT-MIRI Single item auctions

Page 9: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Mechanism design

One way to design mechanism combines prizing withallocations.

We will focus on the study of some auctions:How to sell items to potential buyers with private valuations.

Objective: truth-telling

AGT-MIRI Single item auctions

Page 10: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Mechanism design

One way to design mechanism combines prizing withallocations.

We will focus on the study of some auctions:How to sell items to potential buyers with private valuations.

Objective: truth-telling

AGT-MIRI Single item auctions

Page 11: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Mechanism design

One way to design mechanism combines prizing withallocations.

We will focus on the study of some auctions:How to sell items to potential buyers with private valuations.

Objective: truth-telling

AGT-MIRI Single item auctions

Page 12: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

1 Mechanism design

2 Auctions:Context and Definitions

3 Single item auctions

4 Analyzing auctions

5 Revenue in auctions

AGT-MIRI Single item auctions

Page 13: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

Prices

What is the right price for objects?

The government wants to sell a big building.

Buyer 1: willing to pay 200 Billion.Buyer 2: willing to pay 100 Billion.Buyer 3: does not need the building, but wants to buy it if hecan resale it with a profit.

But, all those values are private, known only by the buyer.

how to get the building worth?

AGT-MIRI Single item auctions

Page 14: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

Prices

What is the right price for objects?

The government wants to sell a big building.

Buyer 1: willing to pay 200 Billion.Buyer 2: willing to pay 100 Billion.Buyer 3: does not need the building, but wants to buy it if hecan resale it with a profit.

But, all those values are private, known only by the buyer.

how to get the building worth?

AGT-MIRI Single item auctions

Page 15: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

Prices

What is the right price for objects?

The government wants to sell a big building.

Buyer 1: willing to pay 200 Billion.Buyer 2: willing to pay 100 Billion.Buyer 3: does not need the building, but wants to buy it if hecan resale it with a profit.

But, all those values are private, known only by the buyer.

how to get the building worth?

AGT-MIRI Single item auctions

Page 16: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

Prices

What is the right price for objects?

The government wants to sell a big building.

Buyer 1: willing to pay 200 Billion.Buyer 2: willing to pay 100 Billion.Buyer 3: does not need the building, but wants to buy it if hecan resale it with a profit.

But, all those values are private, known only by the buyer.

how to get the building worth?

AGT-MIRI Single item auctions

Page 17: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

Prices

What is the right price for objects?

The government wants to sell a big building.

Buyer 1: willing to pay 200 Billion.Buyer 2: willing to pay 100 Billion.Buyer 3: does not need the building, but wants to buy it if hecan resale it with a profit.

But, all those values are private, known only by the buyer.

how to get the building worth?

AGT-MIRI Single item auctions

Page 18: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

Prices

Even when the true preferences of the buyers are knownit is not clear how to price the objects and how to allocatethem.

Buyers might lie and manipulate to get better prices and/orbetter allocation.

How can the true preferences be revealed?

At which cost?

AGT-MIRI Single item auctions

Page 19: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

Prices

Even when the true preferences of the buyers are knownit is not clear how to price the objects and how to allocatethem.

Buyers might lie and manipulate to get better prices and/orbetter allocation.

How can the true preferences be revealed?

At which cost?

AGT-MIRI Single item auctions

Page 20: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

Prices

Even when the true preferences of the buyers are knownit is not clear how to price the objects and how to allocatethem.

Buyers might lie and manipulate to get better prices and/orbetter allocation.

How can the true preferences be revealed?

At which cost?

AGT-MIRI Single item auctions

Page 21: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

Prices

Even when the true preferences of the buyers are knownit is not clear how to price the objects and how to allocatethem.

Buyers might lie and manipulate to get better prices and/orbetter allocation.

How can the true preferences be revealed?

At which cost?

AGT-MIRI Single item auctions

Page 22: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

Auction theory

Auction theory is a sub-field of Mechanism Design.

Aim: Design and analyze the rules and properties of anauction.

Goal: Design an auction so that in equilibrium we get theresults we want.

As in Game theory we rely on rationality.

AGT-MIRI Single item auctions

Page 23: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

Auction theory

Auction theory is a sub-field of Mechanism Design.

Aim: Design and analyze the rules and properties of anauction.

Goal: Design an auction so that in equilibrium we get theresults we want.

As in Game theory we rely on rationality.

AGT-MIRI Single item auctions

Page 24: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

Auction theory

Auction theory is a sub-field of Mechanism Design.

Aim: Design and analyze the rules and properties of anauction.

Goal:

Design an auction so that in equilibrium we get theresults we want.

As in Game theory we rely on rationality.

AGT-MIRI Single item auctions

Page 25: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

Auction theory

Auction theory is a sub-field of Mechanism Design.

Aim: Design and analyze the rules and properties of anauction.

Goal: Design an auction so that in equilibrium we get theresults we want.

As in Game theory we rely on rationality.

AGT-MIRI Single item auctions

Page 26: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

Auction theory

Auction theory is a sub-field of Mechanism Design.

Aim: Design and analyze the rules and properties of anauction.

Goal: Design an auction so that in equilibrium we get theresults we want.

As in Game theory we rely on rationality.

AGT-MIRI Single item auctions

Page 27: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

What is an Auction?

An auction is a mechanism to allocate resources among agroup of bidders.

An auction model includes three major parts:

The set of possible resource allocations.The number (or portion) of goods of each type including legalor other restrictions on how the goods may be allocated.Rules for bidding and clearing.A procedure to determine who wins what (allocation) and howmuch pays (payment) on the basis of the received information.

AGT-MIRI Single item auctions

Page 28: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

What is an Auction?

An auction is a mechanism to allocate resources among agroup of bidders.

An auction model includes three major parts:

The set of possible resource allocations.The number (or portion) of goods of each type including legalor other restrictions on how the goods may be allocated.Rules for bidding and clearing.A procedure to determine who wins what (allocation) and howmuch pays (payment) on the basis of the received information.

AGT-MIRI Single item auctions

Page 29: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

What is an Auction?

An auction is a mechanism to allocate resources among agroup of bidders.

An auction model includes three major parts:

The set of possible resource allocations.The number (or portion) of goods of each type including legalor other restrictions on how the goods may be allocated.Rules for bidding and clearing.A procedure to determine who wins what (allocation) and howmuch pays (payment) on the basis of the received information.

AGT-MIRI Single item auctions

Page 30: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

What is an Auction?

An auction is a mechanism to allocate resources among agroup of bidders.

An auction model includes three major parts:

The set of possible resource allocations.

The number (or portion) of goods of each type including legalor other restrictions on how the goods may be allocated.Rules for bidding and clearing.A procedure to determine who wins what (allocation) and howmuch pays (payment) on the basis of the received information.

AGT-MIRI Single item auctions

Page 31: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

What is an Auction?

An auction is a mechanism to allocate resources among agroup of bidders.

An auction model includes three major parts:

The set of possible resource allocations.The number (or portion) of goods of each type including legalor other restrictions on how the goods may be allocated.

Rules for bidding and clearing.A procedure to determine who wins what (allocation) and howmuch pays (payment) on the basis of the received information.

AGT-MIRI Single item auctions

Page 32: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

What is an Auction?

An auction is a mechanism to allocate resources among agroup of bidders.

An auction model includes three major parts:

The set of possible resource allocations.The number (or portion) of goods of each type including legalor other restrictions on how the goods may be allocated.Rules for bidding and clearing.

A procedure to determine who wins what (allocation) and howmuch pays (payment) on the basis of the received information.

AGT-MIRI Single item auctions

Page 33: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

What is an Auction?

An auction is a mechanism to allocate resources among agroup of bidders.

An auction model includes three major parts:

The set of possible resource allocations.The number (or portion) of goods of each type including legalor other restrictions on how the goods may be allocated.Rules for bidding and clearing.A procedure to determine who wins what (allocation) and howmuch pays (payment) on the basis of the received information.

AGT-MIRI Single item auctions

Page 34: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

Strategic component?

Bidders decide the information that is revealed in theinteraction.

When?

What?

To whom?

AGT-MIRI Single item auctions

Page 35: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

Strategic component?

Bidders decide the information that is revealed in theinteraction.

When?

What?

To whom?

AGT-MIRI Single item auctions

Page 36: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

PricesAuctions

Strategic component?

Bidders decide the information that is revealed in theinteraction.

When?

What?

To whom?

AGT-MIRI Single item auctions

Page 37: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

1 Mechanism design

2 Auctions:Context and Definitions

3 Single item auctions

4 Analyzing auctions

5 Revenue in auctions

AGT-MIRI Single item auctions

Page 38: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Single item auctions

For today’s lecture assume that we have a single item or good tosell.

AGT-MIRI Single item auctions

Page 39: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Open auction

The auctioneer and the bidders interact physically.

AGT-MIRI Single item auctions

Page 40: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

English Auction

AGT-MIRI Single item auctions

Page 41: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

English Auction

The auctioneer starts the bidding at some reservation price.

The bidders then shout out ascending prices.

Once bidders stop shouting, the highest bidder gets the goodat the declared price.

AGT-MIRI Single item auctions

Page 42: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

English Auction

The auctioneer starts the bidding at some reservation price.

The bidders then shout out ascending prices.

Once bidders stop shouting, the highest bidder gets the goodat the declared price.

AGT-MIRI Single item auctions

Page 43: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

English Auction

The auctioneer starts the bidding at some reservation price.

The bidders then shout out ascending prices.

Once bidders stop shouting, the highest bidder gets the goodat the declared price.

AGT-MIRI Single item auctions

Page 44: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

English Auction

The auctioneer starts the bidding at some reservation price.

The bidders then shout out ascending prices.

Once bidders stop shouting, the highest bidder gets the goodat the declared price.

AGT-MIRI Single item auctions

Page 45: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Japanese Auction

AGT-MIRI Single item auctions

Page 46: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Japanese Auction

The auctioneer calls out ascending prices.

All bidders start out standing, when the price reaches a levelthat a bidder is not willing to pay, that bidder sits down.

Once a bidder sits down, they can’t get back up

The only action that a bidder may take is to drop out of theauction

The last person standing gets the good at the last priceshouted.

analytically more tractable than English because jump biddingcan’t occur.

AGT-MIRI Single item auctions

Page 47: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Japanese Auction

The auctioneer calls out ascending prices.

All bidders start out standing, when the price reaches a levelthat a bidder is not willing to pay, that bidder sits down.

Once a bidder sits down, they can’t get back up

The only action that a bidder may take is to drop out of theauction

The last person standing gets the good at the last priceshouted.

analytically more tractable than English because jump biddingcan’t occur.

AGT-MIRI Single item auctions

Page 48: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Japanese Auction

The auctioneer calls out ascending prices.

All bidders start out standing, when the price reaches a levelthat a bidder is not willing to pay, that bidder sits down.

Once a bidder sits down, they can’t get back up

The only action that a bidder may take is to drop out of theauction

The last person standing gets the good at the last priceshouted.

analytically more tractable than English because jump biddingcan’t occur.

AGT-MIRI Single item auctions

Page 49: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Japanese Auction

The auctioneer calls out ascending prices.

All bidders start out standing, when the price reaches a levelthat a bidder is not willing to pay, that bidder sits down.

Once a bidder sits down, they can’t get back up

The only action that a bidder may take is to drop out of theauction

The last person standing gets the good at the last priceshouted.

analytically more tractable than English because jump biddingcan’t occur.

AGT-MIRI Single item auctions

Page 50: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Japanese Auction

The auctioneer calls out ascending prices.

All bidders start out standing, when the price reaches a levelthat a bidder is not willing to pay, that bidder sits down.

Once a bidder sits down, they can’t get back up

The only action that a bidder may take is to drop out of theauction

The last person standing gets the good at the last priceshouted.

analytically more tractable than English because jump biddingcan’t occur.

AGT-MIRI Single item auctions

Page 51: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Japanese Auction

The auctioneer calls out ascending prices.

All bidders start out standing, when the price reaches a levelthat a bidder is not willing to pay, that bidder sits down.

Once a bidder sits down, they can’t get back up

The only action that a bidder may take is to drop out of theauction

The last person standing gets the good at the last priceshouted.

analytically more tractable than English because jump biddingcan’t occur.

AGT-MIRI Single item auctions

Page 52: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Japanese Auction

The auctioneer calls out ascending prices.

All bidders start out standing, when the price reaches a levelthat a bidder is not willing to pay, that bidder sits down.

Once a bidder sits down, they can’t get back up

The only action that a bidder may take is to drop out of theauction

The last person standing gets the good at the last priceshouted.

analytically more tractable than English because jump biddingcan’t occur.

AGT-MIRI Single item auctions

Page 53: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Dutch Auction

AGT-MIRI Single item auctions

Page 54: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Dutch Auction

The auctioneer starts a clock at some high value; it descends

At some point, a bidder shouts mine! and gets the good atthe price shown on the clock.

AGT-MIRI Single item auctions

Page 55: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Dutch Auction

The auctioneer starts a clock at some high value; it descends

At some point, a bidder shouts mine! and gets the good atthe price shown on the clock.

AGT-MIRI Single item auctions

Page 56: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Dutch Auction

The auctioneer starts a clock at some high value; it descends

At some point, a bidder shouts mine! and gets the good atthe price shown on the clock.

AGT-MIRI Single item auctions

Page 57: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Sealed-Bid auctions

AGT-MIRI Single item auctions

Page 58: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Sealed bid auctions

The auctioneer and the bidders do not interact physically.

The bidders submit their bid privately to the auctioneer.

The bidder on the basis of the bid sets allocation and price.

AGT-MIRI Single item auctions

Page 59: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

First price (FP) Auction

The bidders write down a price and send it to the auctioneer.

The auctioneer awards the good to the bidder with thehighest bid.

The winner pays the amount of his bid.

AGT-MIRI Single item auctions

Page 60: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

First price (FP) Auction

The bidders write down a price and send it to the auctioneer.

The auctioneer awards the good to the bidder with thehighest bid.

The winner pays the amount of his bid.

AGT-MIRI Single item auctions

Page 61: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

First price (FP) Auction

The bidders write down a price and send it to the auctioneer.

The auctioneer awards the good to the bidder with thehighest bid.

The winner pays the amount of his bid.

AGT-MIRI Single item auctions

Page 62: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

First price (FP) Auction

The bidders write down a price and send it to the auctioneer.

The auctioneer awards the good to the bidder with thehighest bid.

The winner pays the amount of his bid.

AGT-MIRI Single item auctions

Page 63: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Second price (SP) Auction

The bidders write down a price and send it to the auctioneer.

The auctioneer awards the good to the bidder with thehighest bid.

The winner pays the amount bid by the second-highest bidder.

Second price auctions are also known as Vickrey auctions.defined by William Vickrey in 1961. Vickrey won the Nobelprize in Economics in 1996.

AGT-MIRI Single item auctions

Page 64: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Second price (SP) Auction

The bidders write down a price and send it to the auctioneer.

The auctioneer awards the good to the bidder with thehighest bid.

The winner pays the amount bid by the second-highest bidder.

Second price auctions are also known as Vickrey auctions.defined by William Vickrey in 1961. Vickrey won the Nobelprize in Economics in 1996.

AGT-MIRI Single item auctions

Page 65: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Second price (SP) Auction

The bidders write down a price and send it to the auctioneer.

The auctioneer awards the good to the bidder with thehighest bid.

The winner pays the amount bid by the second-highest bidder.

Second price auctions are also known as Vickrey auctions.defined by William Vickrey in 1961. Vickrey won the Nobelprize in Economics in 1996.

AGT-MIRI Single item auctions

Page 66: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Second price (SP) Auction

The bidders write down a price and send it to the auctioneer.

The auctioneer awards the good to the bidder with thehighest bid.

The winner pays the amount bid by the second-highest bidder.

Second price auctions are also known as Vickrey auctions.defined by William Vickrey in 1961. Vickrey won the Nobelprize in Economics in 1996.

AGT-MIRI Single item auctions

Page 67: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

Second price (SP) Auction

The bidders write down a price and send it to the auctioneer.

The auctioneer awards the good to the bidder with thehighest bid.

The winner pays the amount bid by the second-highest bidder.

Second price auctions are also known as Vickrey auctions.defined by William Vickrey in 1961. Vickrey won the Nobelprize in Economics in 1996.

AGT-MIRI Single item auctions

Page 68: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

All-Pay Auction

The bidders write down a price and send it to the auctioneer.

The auctioneer awards the good to the bidder with thehighest bid.

Everyone pays the amount of their bid regardless of whetheror not they get the good.

AGT-MIRI Single item auctions

Page 69: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

All-Pay Auction

The bidders write down a price and send it to the auctioneer.

The auctioneer awards the good to the bidder with thehighest bid.

Everyone pays the amount of their bid regardless of whetheror not they get the good.

AGT-MIRI Single item auctions

Page 70: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

All-Pay Auction

The bidders write down a price and send it to the auctioneer.

The auctioneer awards the good to the bidder with thehighest bid.

Everyone pays the amount of their bid regardless of whetheror not they get the good.

AGT-MIRI Single item auctions

Page 71: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Open auctionsSealed-Bid auctions

All-Pay Auction

The bidders write down a price and send it to the auctioneer.

The auctioneer awards the good to the bidder with thehighest bid.

Everyone pays the amount of their bid regardless of whetheror not they get the good.

AGT-MIRI Single item auctions

Page 72: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

1 Mechanism design

2 Auctions:Context and Definitions

3 Single item auctions

4 Analyzing auctions

5 Revenue in auctions

AGT-MIRI Single item auctions

Page 73: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Auctioneer goals

A seller (“auctioneer”) may have several goals.

Revenue: maximize profit.

Efficiency: maximize social welfare:Give the item to the buyer that wants it the most. (regardlessof payments.)

Fairness:An auction that greedily maximizes the total utility of all users(i.e., the social welfare) in each round could lead to a subsetof secondary users starving for products.

AGT-MIRI Single item auctions

Page 74: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Auctioneer goals

A seller (“auctioneer”) may have several goals.

Revenue: maximize profit.

Efficiency: maximize social welfare:

Give the item to the buyer that wants it the most. (regardlessof payments.)

Fairness:An auction that greedily maximizes the total utility of all users(i.e., the social welfare) in each round could lead to a subsetof secondary users starving for products.

AGT-MIRI Single item auctions

Page 75: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Auctioneer goals

A seller (“auctioneer”) may have several goals.

Revenue: maximize profit.

Efficiency: maximize social welfare:Give the item to the buyer that wants it the most. (regardlessof payments.)

Fairness:An auction that greedily maximizes the total utility of all users(i.e., the social welfare) in each round could lead to a subsetof secondary users starving for products.

AGT-MIRI Single item auctions

Page 76: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Auctioneer goals

A seller (“auctioneer”) may have several goals.

Revenue: maximize profit.

Efficiency: maximize social welfare:Give the item to the buyer that wants it the most. (regardlessof payments.)

Fairness:An auction that greedily maximizes the total utility of all users(i.e., the social welfare) in each round could lead to a subsetof secondary users starving for products.

AGT-MIRI Single item auctions

Page 77: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Bidder goal

Auctions are used precisely because the seller is unsure aboutthe values that bidders attach to the object being sold.

A valuation is the maximum amount each bidder is willing topay.

If each bidder knows the value of the object to himself at thetime of bidding, the situation is called one of private values.

If the object has a value and the players have some believe onsuch value, the situation is called one of common values.

A bidder wants to get the object as cheap as possible.

AGT-MIRI Single item auctions

Page 78: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Bidder goal

Auctions are used precisely because the seller is unsure aboutthe values that bidders attach to the object being sold.

A valuation is the maximum amount each bidder is willing topay.

If each bidder knows the value of the object to himself at thetime of bidding, the situation is called one of private values.

If the object has a value and the players have some believe onsuch value, the situation is called one of common values.

A bidder wants to get the object as cheap as possible.

AGT-MIRI Single item auctions

Page 79: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Bidder goal

Auctions are used precisely because the seller is unsure aboutthe values that bidders attach to the object being sold.

A valuation is the maximum amount each bidder is willing topay.

If each bidder knows the value of the object to himself at thetime of bidding, the situation is called one of private values.

If the object has a value and the players have some believe onsuch value, the situation is called one of common values.

A bidder wants to get the object as cheap as possible.

AGT-MIRI Single item auctions

Page 80: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Bidder goal

Auctions are used precisely because the seller is unsure aboutthe values that bidders attach to the object being sold.

A valuation is the maximum amount each bidder is willing topay.

If each bidder knows the value of the object to himself at thetime of bidding, the situation is called one of private values.

If the object has a value and the players have some believe onsuch value, the situation is called one of common values.

A bidder wants to get the object as cheap as possible.

AGT-MIRI Single item auctions

Page 81: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Strategic equivalence

Definition

Two games with the same set of players and the same strategyspace are said to be strategically equivalent if each player’sexpected profits under one of the games are identical to hisexpected profits in the other game.

AGT-MIRI Single item auctions

Page 82: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auctions: strategic equivalences

Lemma

SP-auctions are equivalent to Japanese auctions.

Given that bidders bid truthfully, the outcomes in the twoauctions are the same.

Actually, in Japanese auctions bidders observe additionalinformation: valuations of other players.

This might create a herd phenomena.

But do bidders bid truthfully in SP-auctions?

AGT-MIRI Single item auctions

Page 83: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auctions: strategic equivalences

Lemma

SP-auctions are equivalent to Japanese auctions.

Given that bidders bid truthfully, the outcomes in the twoauctions are the same.

Actually, in Japanese auctions bidders observe additionalinformation: valuations of other players.

This might create a herd phenomena.

But do bidders bid truthfully in SP-auctions?

AGT-MIRI Single item auctions

Page 84: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auctions: strategic equivalences

Lemma

SP-auctions are equivalent to Japanese auctions.

Given that bidders bid truthfully, the outcomes in the twoauctions are the same.

Actually, in Japanese auctions bidders observe additionalinformation: valuations of other players.

This might create a herd phenomena.

But do bidders bid truthfully in SP-auctions?

AGT-MIRI Single item auctions

Page 85: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auction: Modeling

n bidders

Each bidder has value vi for the item willingness to pay.Known only to him – private value.

If Bidder i wins and pays pi , his utility is vi–pi .Her utility is 0 when she loses.

Bidders prefer losing than paying more than their value.

AGT-MIRI Single item auctions

Page 86: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auction: Modeling

n bidders

Each bidder has value vi for the item willingness to pay.Known only to him – private value.

If Bidder i wins and pays pi , his utility is vi–pi .Her utility is 0 when she loses.

Bidders prefer losing than paying more than their value.

AGT-MIRI Single item auctions

Page 87: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auction: Strategies

A strategy for each bidder:

how to bid given your value?

Examples for strategies:

bi (vi ) = vi truthful!bi (vi ) = vi/2bi (vi ) = vi/n if you have information on the number of bidders.If vi < 50, bi (vi ) = vi ; otherwise, bi (vi ) = vi + 17.

The auction is a strategic game, where these strategies arethe pure strategies (infinitely many).

AGT-MIRI Single item auctions

Page 88: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auction: Strategies

A strategy for each bidder:

how to bid given your value?

Examples for strategies:

bi (vi ) = vi truthful!bi (vi ) = vi/2bi (vi ) = vi/n if you have information on the number of bidders.If vi < 50, bi (vi ) = vi ; otherwise, bi (vi ) = vi + 17.

The auction is a strategic game, where these strategies arethe pure strategies (infinitely many).

AGT-MIRI Single item auctions

Page 89: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auction: Strategies

A strategy for each bidder:

how to bid given your value?

Examples for strategies:

bi (vi ) = vi truthful!bi (vi ) = vi/2bi (vi ) = vi/n if you have information on the number of bidders.If vi < 50, bi (vi ) = vi ; otherwise, bi (vi ) = vi + 17.

The auction is a strategic game, where these strategies arethe pure strategies (infinitely many).

AGT-MIRI Single item auctions

Page 90: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auction: Strategies

A strategy for each bidder:

how to bid given your value?

Examples for strategies:

bi (vi ) = vi truthful!bi (vi ) = vi/2bi (vi ) = vi/n if you have information on the number of bidders.If vi < 50, bi (vi ) = vi ; otherwise, bi (vi ) = vi + 17.

The auction is a strategic game, where these strategies arethe pure strategies (infinitely many).

AGT-MIRI Single item auctions

Page 91: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auction: Strategies

A strategy for each bidder:

how to bid given your value?

Examples for strategies:

bi (vi ) = vi truthful!bi (vi ) = vi/2bi (vi ) = vi/n if you have information on the number of bidders.If vi < 50, bi (vi ) = vi ; otherwise, bi (vi ) = vi + 17.

The auction is a strategic game, where these strategies arethe pure strategies (infinitely many).

AGT-MIRI Single item auctions

Page 92: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auctions: Equilibrium behaviour

Theorem

In SP-price auctions truth-telling is a dominant strategy.

In Japanese auctions with private values too.

Let’s prove now that truthfulness is a dominant strategy.

The proof is by case analysis.

We have to show that Bidder 1 will never benefit from biddinga bid that is not v1.

AGT-MIRI Single item auctions

Page 93: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auctions: Equilibrium behaviour

Theorem

In SP-price auctions truth-telling is a dominant strategy.

In Japanese auctions with private values too.

Let’s prove now that truthfulness is a dominant strategy.

The proof is by case analysis.

We have to show that Bidder 1 will never benefit from biddinga bid that is not v1.

AGT-MIRI Single item auctions

Page 94: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auctions: Equilibrium behaviour

Case 1: Bidder 1 wins when bidding v1.

v1 is the highest bid and b2 is the 2nd highest.

Bidder 1 utility is v1 − b2 > 0.

Bidding above b2 will not change anything.

Bidding less than b2 will turn him into a loser. From positiveutility to zero!

No gain from lying!.

AGT-MIRI Single item auctions

Page 95: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auctions: Equilibrium behaviour

Case 1: Bidder 1 wins when bidding v1.

v1 is the highest bid and b2 is the 2nd highest.

Bidder 1 utility is v1 − b2 > 0.

Bidding above b2 will not change anything.

Bidding less than b2 will turn him into a loser. From positiveutility to zero!

No gain from lying!.

AGT-MIRI Single item auctions

Page 96: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auctions: Equilibrium behaviour

Case 1: Bidder 1 wins when bidding v1.

v1 is the highest bid and b2 is the 2nd highest.

Bidder 1 utility is v1 − b2 > 0.

Bidding above b2 will not change anything.

Bidding less than b2 will turn him into a loser. From positiveutility to zero!

No gain from lying!.

AGT-MIRI Single item auctions

Page 97: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auctions: Equilibrium behaviour

Case 1: Bidder 1 wins when bidding v1.

v1 is the highest bid and b2 is the 2nd highest.

Bidder 1 utility is v1 − b2 > 0.

Bidding above b2 will not change anything.

Bidding less than b2 will turn him into a loser. From positiveutility to zero!

No gain from lying!.

AGT-MIRI Single item auctions

Page 98: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auctions: Equilibrium behaviour

Case 2: Bidder 1 loses when bidding v1.

Let b2 be the 2nd highest bid now.

Bidder 1 utility is 0.

Any bid below b2 will gain him zero utility.

Any bid above b2 will gain him either 0 (still not wining)or an utility smaller that v1 − b2 < 0 (losing is better).

Again, no gain from lying!.

AGT-MIRI Single item auctions

Page 99: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auctions: Equilibrium behaviour

Case 2: Bidder 1 loses when bidding v1.

Let b2 be the 2nd highest bid now.

Bidder 1 utility is 0.

Any bid below b2 will gain him zero utility.

Any bid above b2 will gain him either 0 (still not wining)or an utility smaller that v1 − b2 < 0 (losing is better).

Again, no gain from lying!.

AGT-MIRI Single item auctions

Page 100: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auctions: Equilibrium behaviour

Case 2: Bidder 1 loses when bidding v1.

Let b2 be the 2nd highest bid now.

Bidder 1 utility is 0.

Any bid below b2 will gain him zero utility.

Any bid above b2 will gain him either 0 (still not wining)or an utility smaller that v1 − b2 < 0 (losing is better).

Again, no gain from lying!.

AGT-MIRI Single item auctions

Page 101: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auctions: Equilibrium behaviour

Case 2: Bidder 1 loses when bidding v1.

Let b2 be the 2nd highest bid now.

Bidder 1 utility is 0.

Any bid below b2 will gain him zero utility.

Any bid above b2 will gain him either 0 (still not wining)or an utility smaller that v1 − b2 < 0 (losing is better).

Again, no gain from lying!.

AGT-MIRI Single item auctions

Page 102: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auctions: Efficiency

Since SP-auction is truthful, we can conclude it is efficient.

That is, in equilibrium,

the auctioneer allocates the item tothe bidder with the highest value.

With the actual highest value, not just the highest bid.Without assuming anything on the values.

However the seller does not get maximum revenue.

AGT-MIRI Single item auctions

Page 103: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auctions: Efficiency

Since SP-auction is truthful, we can conclude it is efficient.

That is, in equilibrium, the auctioneer allocates the item tothe bidder with the highest value.

With the actual highest value, not just the highest bid.Without assuming anything on the values.

However the seller does not get maximum revenue.

AGT-MIRI Single item auctions

Page 104: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

SP-Auctions: Efficiency

Since SP-auction is truthful, we can conclude it is efficient.

That is, in equilibrium, the auctioneer allocates the item tothe bidder with the highest value.

With the actual highest value, not just the highest bid.Without assuming anything on the values.

However the seller does not get maximum revenue.

AGT-MIRI Single item auctions

Page 105: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP-Auctions Strategic equivalences

Lemma

FP-price auctions are strategically equivalent to Dutch auctions.

Strategies:

FP: Given that no one has a higher bid,what is the maximum I am willing to pay?

Dutch: Given that no body has raised their hand,when should I raise mine?No new information is revealed during the auction!

AGT-MIRI Single item auctions

Page 106: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP-Auctions Strategic equivalences

Lemma

FP-price auctions are strategically equivalent to Dutch auctions.

Strategies:

FP: Given that no one has a higher bid,what is the maximum I am willing to pay?

Dutch: Given that no body has raised their hand,when should I raise mine?

No new information is revealed during the auction!

AGT-MIRI Single item auctions

Page 107: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP-Auctions Strategic equivalences

Lemma

FP-price auctions are strategically equivalent to Dutch auctions.

Strategies:

FP: Given that no one has a higher bid,what is the maximum I am willing to pay?

Dutch: Given that no body has raised their hand,when should I raise mine?No new information is revealed during the auction!

AGT-MIRI Single item auctions

Page 108: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP-Auctions: properties

FP and Dutch auctions are

Equivalent.

Efficient?Yes, in equilibrium the good will be allocated to the playerwith a higher valuation.

Truthful?v1 = 100 and other’s highest bid b2 = 30.Player 1 by bidding 31 gets the good and a positive benefit.No truthfulness in the strategic setting.We continue the analysis on Bayesian games.

AGT-MIRI Single item auctions

Page 109: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP-Auctions: properties

FP and Dutch auctions are

Equivalent.

Efficient?Yes, in equilibrium the good will be allocated to the playerwith a higher valuation.

Truthful?

v1 = 100 and other’s highest bid b2 = 30.Player 1 by bidding 31 gets the good and a positive benefit.No truthfulness in the strategic setting.We continue the analysis on Bayesian games.

AGT-MIRI Single item auctions

Page 110: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP-Auctions: properties

FP and Dutch auctions are

Equivalent.

Efficient?Yes, in equilibrium the good will be allocated to the playerwith a higher valuation.

Truthful?v1 = 100 and other’s highest bid b2 = 30.

Player 1 by bidding 31 gets the good and a positive benefit.No truthfulness in the strategic setting.We continue the analysis on Bayesian games.

AGT-MIRI Single item auctions

Page 111: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP-Auctions: properties

FP and Dutch auctions are

Equivalent.

Efficient?Yes, in equilibrium the good will be allocated to the playerwith a higher valuation.

Truthful?v1 = 100 and other’s highest bid b2 = 30.Player 1 by bidding 31

gets the good and a positive benefit.No truthfulness in the strategic setting.We continue the analysis on Bayesian games.

AGT-MIRI Single item auctions

Page 112: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP-Auctions: properties

FP and Dutch auctions are

Equivalent.

Efficient?Yes, in equilibrium the good will be allocated to the playerwith a higher valuation.

Truthful?v1 = 100 and other’s highest bid b2 = 30.Player 1 by bidding 31 gets the good and a positive benefit.

No truthfulness in the strategic setting.We continue the analysis on Bayesian games.

AGT-MIRI Single item auctions

Page 113: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP-Auctions: properties

FP and Dutch auctions are

Equivalent.

Efficient?Yes, in equilibrium the good will be allocated to the playerwith a higher valuation.

Truthful?v1 = 100 and other’s highest bid b2 = 30.Player 1 by bidding 31 gets the good and a positive benefit.No truthfulness in the strategic setting.

We continue the analysis on Bayesian games.

AGT-MIRI Single item auctions

Page 114: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP-Auctions: properties

FP and Dutch auctions are

Equivalent.

Efficient?Yes, in equilibrium the good will be allocated to the playerwith a higher valuation.

Truthful?v1 = 100 and other’s highest bid b2 = 30.Player 1 by bidding 31 gets the good and a positive benefit.No truthfulness in the strategic setting.We continue the analysis on Bayesian games.

AGT-MIRI Single item auctions

Page 115: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP auctions: Bayesian analysis

How do people behave?

They have beliefs on the valuations of the other players!

As usual beliefs are modeled with probability distributions.

Bidders do not know their opponent’s values, i.e., there isincomplete information.Each bidder’s strategy must maximize her expected payoffaccounting for the uncertainty about opponent values.

AGT-MIRI Single item auctions

Page 116: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP auctions: Bayesian analysis

How do people behave?

They have beliefs on the valuations of the other players!

As usual beliefs are modeled with probability distributions.

Bidders do not know their opponent’s values, i.e., there isincomplete information.Each bidder’s strategy must maximize her expected payoffaccounting for the uncertainty about opponent values.

AGT-MIRI Single item auctions

Page 117: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP auctions: Bayesian analysis

How do people behave?

They have beliefs on the valuations of the other players!

As usual beliefs are modeled with probability distributions.

Bidders do not know their opponent’s values, i.e., there isincomplete information.Each bidder’s strategy must maximize her expected payoffaccounting for the uncertainty about opponent values.

AGT-MIRI Single item auctions

Page 118: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP auctions: Bayesian analysis

How do people behave?

They have beliefs on the valuations of the other players!

As usual beliefs are modeled with probability distributions.

Bidders do not know their opponent’s values, i.e., there isincomplete information.Each bidder’s strategy must maximize her expected payoffaccounting for the uncertainty about opponent values.

AGT-MIRI Single item auctions

Page 119: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP auctions: Bayesian analysis

How do people behave?

They have beliefs on the valuations of the other players!

As usual beliefs are modeled with probability distributions.

Bidders do not know their opponent’s values, i.e., there isincomplete information.

Each bidder’s strategy must maximize her expected payoffaccounting for the uncertainty about opponent values.

AGT-MIRI Single item auctions

Page 120: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP auctions: Bayesian analysis

How do people behave?

They have beliefs on the valuations of the other players!

As usual beliefs are modeled with probability distributions.

Bidders do not know their opponent’s values, i.e., there isincomplete information.Each bidder’s strategy must maximize her expected payoffaccounting for the uncertainty about opponent values.

AGT-MIRI Single item auctions

Page 121: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Auctions with uniform distributions

A simple Bayesian auction model:

2 buyersValues are between 0 and 1.Values are distributed uniformly on [0, 1]

What is the equilibrium in this game of incompleteinformation?

AGT-MIRI Single item auctions

Page 122: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Auctions with uniform distributions

A simple Bayesian auction model:

2 buyersValues are between 0 and 1.Values are distributed uniformly on [0, 1]

What is the equilibrium in this game of incompleteinformation?

AGT-MIRI Single item auctions

Page 123: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Auctions with uniform distributions

A simple Bayesian auction model:

2 buyersValues are between 0 and 1.Values are distributed uniformly on [0, 1]

What is the equilibrium in this game of incompleteinformation?

AGT-MIRI Single item auctions

Page 124: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Auctions with uniform distributions

A simple Bayesian auction model:

2 buyersValues are between 0 and 1.Values are distributed uniformly on [0, 1]

What is the equilibrium in this game of incompleteinformation?

AGT-MIRI Single item auctions

Page 125: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Simple FP: Equilibrium

2 bidders uniform distributionBidding b(v) = v/2 is an equilibrium

Assume that Bidder 2’s strategy is b2(v) = v2/2.

Let us show that b1(v) = v1/2 is a best response to Bidder 2.(clearly, no need to bid above v1).

Bidder 1’s utility is:

Prob[b1 > b2] (v1 − b1) =

=Prob[b1 > v2/2] (v1 − b1)

=2b1 (v1 − b1)

maximizing for b1 we have: [2b1 (v1 − b1)]′ = 2v1 − 4b1 = 0which gives b1 = v1/2

AGT-MIRI Single item auctions

Page 126: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Simple FP: Equilibrium

2 bidders uniform distributionBidding b(v) = v/2 is an equilibrium

Assume that Bidder 2’s strategy is b2(v) = v2/2.

Let us show that b1(v) = v1/2 is a best response to Bidder 2.(clearly, no need to bid above v1).

Bidder 1’s utility is:

Prob[b1 > b2] (v1 − b1) =

=Prob[b1 > v2/2] (v1 − b1)

=2b1 (v1 − b1)

maximizing for b1 we have: [2b1 (v1 − b1)]′ = 2v1 − 4b1 = 0which gives b1 = v1/2

AGT-MIRI Single item auctions

Page 127: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Simple FP: Equilibrium

2 bidders uniform distributionBidding b(v) = v/2 is an equilibrium

Assume that Bidder 2’s strategy is b2(v) = v2/2.

Let us show that b1(v) = v1/2 is a best response to Bidder 2.(clearly, no need to bid above v1).

Bidder 1’s utility is:

Prob[b1 > b2] (v1 − b1) =

=Prob[b1 > v2/2] (v1 − b1)

=2b1 (v1 − b1)

maximizing for b1 we have: [2b1 (v1 − b1)]′ = 2v1 − 4b1 = 0which gives b1 = v1/2

AGT-MIRI Single item auctions

Page 128: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Simple FP: Equilibrium

2 bidders uniform distributionBidding b(v) = v/2 is an equilibrium

Assume that Bidder 2’s strategy is b2(v) = v2/2.

Let us show that b1(v) = v1/2 is a best response to Bidder 2.(clearly, no need to bid above v1).

Bidder 1’s utility is:

Prob[b1 > b2] (v1 − b1) =

=Prob[b1 > v2/2] (v1 − b1)

=2b1 (v1 − b1)

maximizing for b1 we have: [2b1 (v1 − b1)]′ = 2v1 − 4b1 = 0which gives b1 = v1/2

AGT-MIRI Single item auctions

Page 129: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Simple FP: Equilibrium

2 bidders uniform distributionBidding b(v) = v/2 is an equilibrium

Assume that Bidder 2’s strategy is b2(v) = v2/2.

Let us show that b1(v) = v1/2 is a best response to Bidder 2.(clearly, no need to bid above v1).

Bidder 1’s utility is:

Prob[b1 > b2] (v1 − b1) =

=Prob[b1 > v2/2] (v1 − b1)

=2b1 (v1 − b1)

maximizing for b1 we have: [2b1 (v1 − b1)]′ = 2v1 − 4b1 = 0which gives b1 = v1/2

AGT-MIRI Single item auctions

Page 130: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Simple FP: Equilibrium

2 bidders uniform distributionBidding b(v) = v/2 is an equilibrium

Assume that Bidder 2’s strategy is b2(v) = v2/2.

Let us show that b1(v) = v1/2 is a best response to Bidder 2.(clearly, no need to bid above v1).

Bidder 1’s utility is:

Prob[b1 > b2] (v1 − b1) =

=Prob[b1 > v2/2] (v1 − b1)

=2b1 (v1 − b1)

maximizing for b1 we have:

[2b1 (v1 − b1)]′ = 2v1 − 4b1 = 0which gives b1 = v1/2

AGT-MIRI Single item auctions

Page 131: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

Simple FP: Equilibrium

2 bidders uniform distributionBidding b(v) = v/2 is an equilibrium

Assume that Bidder 2’s strategy is b2(v) = v2/2.

Let us show that b1(v) = v1/2 is a best response to Bidder 2.(clearly, no need to bid above v1).

Bidder 1’s utility is:

Prob[b1 > b2] (v1 − b1) =

=Prob[b1 > v2/2] (v1 − b1)

=2b1 (v1 − b1)

maximizing for b1 we have: [2b1 (v1 − b1)]′ = 2v1 − 4b1 = 0which gives b1 = v1/2

AGT-MIRI Single item auctions

Page 132: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP: uniform values

We consider the simple Bayesian model

n biddersValues drawn uniformly form [0, 1]

Theorem

In a FP auction with n bidders under the uniform values model, thestrategy bi = n−1

n vi , for 1 ≤ i ≤ n, is a Bayesian Nash equilibrium.

AGT-MIRI Single item auctions

Page 133: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP: uniform values

We consider the simple Bayesian model

n biddersValues drawn uniformly form [0, 1]

Theorem

In a FP auction with n bidders under the uniform values model, thestrategy bi = n−1

n vi , for 1 ≤ i ≤ n, is a Bayesian Nash equilibrium.

AGT-MIRI Single item auctions

Page 134: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP: uniform values

We consider the simple Bayesian model

n biddersValues drawn uniformly form [0, 1]

Theorem

In a FP auction with n bidders under the uniform values model, thestrategy bi = n−1

n vi , for 1 ≤ i ≤ n, is a Bayesian Nash equilibrium.

AGT-MIRI Single item auctions

Page 135: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP uniform values: Efficiency

An auction is efficient if, in a Bayesian Nash equilibrium, thebidder with the highest value always wins.

Thus, in the uniform value model FP is efficient.

AGT-MIRI Single item auctions

Page 136: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP uniform values: Efficiency

An auction is efficient if, in a Bayesian Nash equilibrium, thebidder with the highest value always wins.

Thus, in the uniform value model FP is efficient.

AGT-MIRI Single item auctions

Page 137: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

FP uniform values: Efficiency

An auction is efficient if, in a Bayesian Nash equilibrium, thebidder with the highest value always wins.

Thus, in the uniform value model FP is efficient.

AGT-MIRI Single item auctions

Page 138: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

English and Japanese auctions

A much more complicated strategy space than sealed bidauctions

extensive form gamebidders are able to condition their bids on information revealedby othersin the case of English auctions, the ability to place jump bids

Independent private values model (IPV): the n bidders havevalues v1, . . . , vn identically and independently distributedwith cdf F (·).

Theorem

Under the IPV model, it is a dominant strategy for bidders to bidup to (and not beyond) their valuations in both Japanese andEnglish auctions.

AGT-MIRI Single item auctions

Page 139: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

English and Japanese auctions

A much more complicated strategy space than sealed bidauctions

extensive form gamebidders are able to condition their bids on information revealedby othersin the case of English auctions, the ability to place jump bids

Independent private values model (IPV): the n bidders havevalues v1, . . . , vn identically and independently distributedwith cdf F (·).

Theorem

Under the IPV model, it is a dominant strategy for bidders to bidup to (and not beyond) their valuations in both Japanese andEnglish auctions.

AGT-MIRI Single item auctions

Page 140: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

English and Japanese auctions

A much more complicated strategy space than sealed bidauctions

extensive form gamebidders are able to condition their bids on information revealedby othersin the case of English auctions, the ability to place jump bids

Independent private values model (IPV): the n bidders havevalues v1, . . . , vn identically and independently distributedwith cdf F (·).

Theorem

Under the IPV model, it is a dominant strategy for bidders to bidup to (and not beyond) their valuations in both Japanese andEnglish auctions.

AGT-MIRI Single item auctions

Page 141: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

English and Japanese auctions

A much more complicated strategy space than sealed bidauctions

extensive form gamebidders are able to condition their bids on information revealedby othersin the case of English auctions, the ability to place jump bids

Independent private values model (IPV): the n bidders havevalues v1, . . . , vn identically and independently distributedwith cdf F (·).

Theorem

Under the IPV model, it is a dominant strategy for bidders to bidup to (and not beyond) their valuations in both Japanese andEnglish auctions.

AGT-MIRI Single item auctions

Page 142: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

GoalsSP AuctionsFP AuctionsEnglish and Japanese auctions

English and Japanese auctions

A much more complicated strategy space than sealed bidauctions

extensive form gamebidders are able to condition their bids on information revealedby othersin the case of English auctions, the ability to place jump bids

Independent private values model (IPV): the n bidders havevalues v1, . . . , vn identically and independently distributedwith cdf F (·).

Theorem

Under the IPV model, it is a dominant strategy for bidders to bidup to (and not beyond) their valuations in both Japanese andEnglish auctions.

AGT-MIRI Single item auctions

Page 143: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

1 Mechanism design

2 Auctions:Context and Definitions

3 Single item auctions

4 Analyzing auctions

5 Revenue in auctions

AGT-MIRI Single item auctions

Page 144: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Optimal auctions

Usually the term optimal auctions stands for revenuemaximization.

What is maximal revenue? optimal expected revenue inequilibrium.

Assuming a probability distribution on the values.Over all the possible mechanisms.Under individual-rationality constraints.

AGT-MIRI Single item auctions

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Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Optimal auctions

Usually the term optimal auctions stands for revenuemaximization.

What is maximal revenue? optimal expected revenue inequilibrium.

Assuming a probability distribution on the values.Over all the possible mechanisms.Under individual-rationality constraints.

AGT-MIRI Single item auctions

Page 146: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Optimal auctions

Usually the term optimal auctions stands for revenuemaximization.

What is maximal revenue?

optimal expected revenue inequilibrium.

Assuming a probability distribution on the values.Over all the possible mechanisms.Under individual-rationality constraints.

AGT-MIRI Single item auctions

Page 147: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Optimal auctions

Usually the term optimal auctions stands for revenuemaximization.

What is maximal revenue? optimal expected revenue inequilibrium.

Assuming a probability distribution on the values.Over all the possible mechanisms.Under individual-rationality constraints.

AGT-MIRI Single item auctions

Page 148: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Optimal auctions

Usually the term optimal auctions stands for revenuemaximization.

What is maximal revenue? optimal expected revenue inequilibrium.

Assuming a probability distribution on the values.Over all the possible mechanisms.Under individual-rationality constraints.

AGT-MIRI Single item auctions

Page 149: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Simple auctions with uniform distributions

We consider the simple Bayesian model

2 biddersValues drawn uniformly form [0, 1] x , y

What is the expected revenue gained by SP and FP auctions?

AGT-MIRI Single item auctions

Page 150: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Simple auctions with uniform distributions

We consider the simple Bayesian model

2 biddersValues drawn uniformly form [0, 1] x , y

What is the expected revenue gained by SP and FP auctions?

AGT-MIRI Single item auctions

Page 151: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue in SP Simple auctions with uniform distributions

In a SP auction, the payment is the minimum of the twovalues.

E [revenue] = E [min{x , y}]

Claim: When x , y ≡ U[0, 1] we have E [min{x , y}] = 1/3

AGT-MIRI Single item auctions

Page 152: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue in SP Simple auctions with uniform distributions

In a SP auction, the payment is the minimum of the twovalues.

E [revenue] = E [min{x , y}]

Claim: When x , y ≡ U[0, 1] we have E [min{x , y}] = 1/3

AGT-MIRI Single item auctions

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Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Claim’s proof

Assume that v1 = x .Then, the expected revenue is:

xx

2+ (1− x)x = x − x2

2.

The expectation over all possible x is:

E [min{x , y}] =

∫ 1

0(x − x2

2)dx

=

[x2

2− x3

6

]10

=1

3.

AGT-MIRI Single item auctions

Page 154: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Claim’s proof

Assume that v1 = x .Then, the expected revenue is:

xx

2+ (1− x)x = x − x2

2.

The expectation over all possible x is:

E [min{x , y}] =

∫ 1

0(x − x2

2)dx

=

[x2

2− x3

6

]10

=1

3.

AGT-MIRI Single item auctions

Page 155: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Order statistics

Let v1, . . . , vn be n random variables

The highest realization is called the 1st-order statistic.The second highest is the called 2nd-order statistic.. . .The smallest is the n-th-order statistic.

Example: the uniform distribution, 2 samples.

The expected 1st-order statistic: 2/3Expected efficiency.The expected 2nd-order statistic: 1/3Expected revenue.

AGT-MIRI Single item auctions

Page 156: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Order statistics

Let v1, . . . , vn be n random variables

The highest realization is called the 1st-order statistic.The second highest is the called 2nd-order statistic.. . .The smallest is the n-th-order statistic.

Example: the uniform distribution, 2 samples.

The expected 1st-order statistic: 2/3Expected efficiency.The expected 2nd-order statistic: 1/3Expected revenue.

AGT-MIRI Single item auctions

Page 157: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Order statistics

Let v1, . . . , vn be n random variables

The highest realization is called the 1st-order statistic.The second highest is the called 2nd-order statistic.. . .The smallest is the n-th-order statistic.

Example: the uniform distribution, 2 samples.

The expected 1st-order statistic: 2/3Expected efficiency.The expected 2nd-order statistic: 1/3Expected revenue.

AGT-MIRI Single item auctions

Page 158: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Order statistics

Let v1, . . . , vn be n random variables

The highest realization is called the 1st-order statistic.The second highest is the called 2nd-order statistic.. . .The smallest is the n-th-order statistic.

Example: the uniform distribution, 2 samples.

The expected 1st-order statistic: 2/3Expected efficiency.The expected 2nd-order statistic: 1/3Expected revenue.

AGT-MIRI Single item auctions

Page 159: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Order statistics

Let v1, . . . , vn be n random variables

The highest realization is called the 1st-order statistic.The second highest is the called 2nd-order statistic.. . .The smallest is the n-th-order statistic.

Example: the uniform distribution, 2 samples.

The expected 1st-order statistic: 2/3Expected efficiency.

The expected 2nd-order statistic: 1/3Expected revenue.

AGT-MIRI Single item auctions

Page 160: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Order statistics

Let v1, . . . , vn be n random variables

The highest realization is called the 1st-order statistic.The second highest is the called 2nd-order statistic.. . .The smallest is the n-th-order statistic.

Example: the uniform distribution, 2 samples.

The expected 1st-order statistic: 2/3Expected efficiency.The expected 2nd-order statistic: 1/3Expected revenue.

AGT-MIRI Single item auctions

Page 161: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Order statistics

In general, for the uniform distribution with n samples:

k-th order statistic of n variables is (n + 1− k)/(n + 1)1st-order statistic: n/(n + 1).

AGT-MIRI Single item auctions

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Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue in FP simple auctions with uniform distributions

In a FP simple auction, vi/2 is a bayesian Nash

Revenue is the highest bid.

Thus, expected revenue is

E [revenue] =E [max{v1/2, v2/2}] =1

2E [max{v1, v2}]

=1

2

2

3=

1

3

Same revenue as in SP simple auctions!

AGT-MIRI Single item auctions

Page 163: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue in FP simple auctions with uniform distributions

In a FP simple auction, vi/2 is a bayesian Nash

Revenue is the highest bid.

Thus, expected revenue is

E [revenue] =E [max{v1/2, v2/2}] =1

2E [max{v1, v2}]

=1

2

2

3=

1

3

Same revenue as in SP simple auctions!

AGT-MIRI Single item auctions

Page 164: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue in FP simple auctions with uniform distributions

In a FP simple auction, vi/2 is a bayesian Nash

Revenue is the highest bid.

Thus, expected revenue is

E [revenue] =E [max{v1/2, v2/2}] =1

2E [max{v1, v2}]

=1

2

2

3=

1

3

Same revenue as in SP simple auctions!

AGT-MIRI Single item auctions

Page 165: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue: FP vs. SP auctions with uniform distributions

Revenue in SP:Bidders bid truthfully.Revenue is 2nd highest bid:

E [revenue] =n − 1

n + 1

Revenue in FP:Bidders bid.Revenue is highest bid:

E [revenue] =E

[max

{n − 1

nv1, . . . ,

n − 1

nvn

}]=n − 1

nE [max{v1, . . . , vn}] =

n − 1

n

n

n + 1=

n − 1

n + 1

AGT-MIRI Single item auctions

Page 166: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue: FP vs. SP auctions with uniform distributions

Revenue in SP:

Bidders bid truthfully.Revenue is 2nd highest bid:

E [revenue] =n − 1

n + 1

Revenue in FP:Bidders bid.Revenue is highest bid:

E [revenue] =E

[max

{n − 1

nv1, . . . ,

n − 1

nvn

}]=n − 1

nE [max{v1, . . . , vn}] =

n − 1

n

n

n + 1=

n − 1

n + 1

AGT-MIRI Single item auctions

Page 167: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue: FP vs. SP auctions with uniform distributions

Revenue in SP:Bidders bid truthfully.Revenue is 2nd highest bid:

E [revenue] =n − 1

n + 1

Revenue in FP:Bidders bid.Revenue is highest bid:

E [revenue] =E

[max

{n − 1

nv1, . . . ,

n − 1

nvn

}]=n − 1

nE [max{v1, . . . , vn}] =

n − 1

n

n

n + 1=

n − 1

n + 1

AGT-MIRI Single item auctions

Page 168: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue: FP vs. SP auctions with uniform distributions

Revenue in SP:Bidders bid truthfully.Revenue is 2nd highest bid:

E [revenue] =n − 1

n + 1

Revenue in FP:

Bidders bid.Revenue is highest bid:

E [revenue] =E

[max

{n − 1

nv1, . . . ,

n − 1

nvn

}]=n − 1

nE [max{v1, . . . , vn}] =

n − 1

n

n

n + 1=

n − 1

n + 1

AGT-MIRI Single item auctions

Page 169: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue: FP vs. SP auctions with uniform distributions

Revenue in SP:Bidders bid truthfully.Revenue is 2nd highest bid:

E [revenue] =n − 1

n + 1

Revenue in FP:Bidders bid.Revenue is highest bid:

E [revenue] =E

[max

{n − 1

nv1, . . . ,

n − 1

nvn

}]=n − 1

nE [max{v1, . . . , vn}] =

n − 1

n

n

n + 1=

n − 1

n + 1

AGT-MIRI Single item auctions

Page 170: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue: FP vs. SP auctions with uniform distributions

Revenue in SP:Bidders bid truthfully.Revenue is 2nd highest bid:

E [revenue] =n − 1

n + 1

Revenue in FP:Bidders bid.Revenue is highest bid:

E [revenue] =E

[max

{n − 1

nv1, . . . ,

n − 1

nvn

}]=n − 1

nE [max{v1, . . . , vn}] =

n − 1

n

n

n + 1=

n − 1

n + 1

AGT-MIRI Single item auctions

Page 171: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue Equivalence Theorem

Assumptions:

vi ‘s are drawn independently from some F on [a, b].F is continuous and strictly increasing.Bidders are risk neutral: utility is a linear function of hiswealth.

Theorem (The Revenue Equivalence Theorem)

Consider two auction such that:

(same allocation) When player i bids v his probability to win isthe same in the two auctions (for all i and v) in equilibrium.

(normalization) If a player bids a (the lowest possible value)he will pay the same amount in both auctions.

Then, in equilibrium, the two auctions earn the same revenue.

Revenue depends most on allocation than on valuations!

AGT-MIRI Single item auctions

Page 172: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue Equivalence Theorem

Assumptions:vi ‘s are drawn independently from some F on [a, b].F is continuous and strictly increasing.Bidders are risk neutral: utility is a linear function of hiswealth.

Theorem (The Revenue Equivalence Theorem)

Consider two auction such that:

(same allocation) When player i bids v his probability to win isthe same in the two auctions (for all i and v) in equilibrium.

(normalization) If a player bids a (the lowest possible value)he will pay the same amount in both auctions.

Then, in equilibrium, the two auctions earn the same revenue.

Revenue depends most on allocation than on valuations!

AGT-MIRI Single item auctions

Page 173: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue Equivalence Theorem

Assumptions:vi ‘s are drawn independently from some F on [a, b].F is continuous and strictly increasing.Bidders are risk neutral: utility is a linear function of hiswealth.

Theorem (The Revenue Equivalence Theorem)

Consider two auction such that:

(same allocation) When player i bids v his probability to win isthe same in the two auctions (for all i and v) in equilibrium.

(normalization) If a player bids a (the lowest possible value)he will pay the same amount in both auctions.

Then, in equilibrium, the two auctions earn the same revenue.

Revenue depends most on allocation than on valuations!

AGT-MIRI Single item auctions

Page 174: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue Equivalence Theorem

Assumptions:vi ‘s are drawn independently from some F on [a, b].F is continuous and strictly increasing.Bidders are risk neutral: utility is a linear function of hiswealth.

Theorem (The Revenue Equivalence Theorem)

Consider two auction such that:

(same allocation) When player i bids v his probability to win isthe same in the two auctions (for all i and v) in equilibrium.

(normalization) If a player bids a (the lowest possible value)he will pay the same amount in both auctions.

Then, in equilibrium, the two auctions earn the same revenue.

Revenue depends most on allocation than on valuations!AGT-MIRI Single item auctions

Page 175: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue in All-pay auction

Rules

Sealed bidHighest bid winsEveryone pay their bid

Equilibrium with the uniform distribution is

b(v) =n − 1

nvn

Revenue?

AGT-MIRI Single item auctions

Page 176: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue in All-pay auction

Rules

Sealed bidHighest bid winsEveryone pay their bid

Equilibrium with the uniform distribution is

b(v) =n − 1

nvn

Revenue?

AGT-MIRI Single item auctions

Page 177: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue in All-pay auction

Rules

Sealed bidHighest bid winsEveryone pay their bid

Equilibrium with the uniform distribution is

b(v) =n − 1

nvn

Revenue?

AGT-MIRI Single item auctions

Page 178: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue in All-pay auction

Rules

Sealed bidHighest bid winsEveryone pay their bid

Equilibrium with the uniform distribution is

b(v) =n − 1

nvn

Revenue?

AGT-MIRI Single item auctions

Page 179: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue in All-pay auction

Rules

Sealed bidHighest bid winsEveryone pay their bid

Equilibrium with the uniform distribution is

b(v) =n − 1

nvn

Revenue?

AGT-MIRI Single item auctions

Page 180: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue in All-pay auction

Expected payment per each player: her bid

Each bidder bids b(v) = n−1n vn.

Expected payment for each bidder:∫ 1

0

n − 1

nvndv =

n − 1

n

[vn+1

n + 1

]10

=1

n

n − 1

n + 1

Revenue for n bidders

E [revenue] =n − 1

n + 1.

Again revenue equivalence!

AGT-MIRI Single item auctions

Page 181: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue in All-pay auction

Expected payment per each player: her bid

Each bidder bids b(v) = n−1n vn.

Expected payment for each bidder:∫ 1

0

n − 1

nvndv =

n − 1

n

[vn+1

n + 1

]10

=1

n

n − 1

n + 1

Revenue for n bidders

E [revenue] =n − 1

n + 1.

Again revenue equivalence!

AGT-MIRI Single item auctions

Page 182: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue in All-pay auction

Expected payment per each player: her bid

Each bidder bids b(v) = n−1n vn.

Expected payment for each bidder:∫ 1

0

n − 1

nvndv =

n − 1

n

[vn+1

n + 1

]10

=1

n

n − 1

n + 1

Revenue for n bidders

E [revenue] =n − 1

n + 1.

Again revenue equivalence!

AGT-MIRI Single item auctions

Page 183: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue in All-pay auction

Expected payment per each player: her bid

Each bidder bids b(v) = n−1n vn.

Expected payment for each bidder:∫ 1

0

n − 1

nvndv =

n − 1

n

[vn+1

n + 1

]10

=1

n

n − 1

n + 1

Revenue for n bidders

E [revenue] =n − 1

n + 1.

Again revenue equivalence!

AGT-MIRI Single item auctions

Page 184: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue in All-pay auction

Expected payment per each player: her bid

Each bidder bids b(v) = n−1n vn.

Expected payment for each bidder:∫ 1

0

n − 1

nvndv =

n − 1

n

[vn+1

n + 1

]10

=1

n

n − 1

n + 1

Revenue for n bidders

E [revenue] =n − 1

n + 1.

Again revenue equivalence!

AGT-MIRI Single item auctions

Page 185: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue in All-pay auction

Expected payment per each player: her bid

Each bidder bids b(v) = n−1n vn.

Expected payment for each bidder:∫ 1

0

n − 1

nvndv =

n − 1

n

[vn+1

n + 1

]10

=1

n

n − 1

n + 1

Revenue for n bidders

E [revenue] =n − 1

n + 1.

Again revenue equivalence!

AGT-MIRI Single item auctions

Page 186: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

All-pay auctions: examples

crowdsourcing over the internet:

First person to complete a task for me gets a reward.A group of people invest time in the task. (=payment)Only the winner gets the reward.

Advertising auction:

Collect suggestion for campaigns, choose a winner.All advertiser incur cost of preparing the campaign.Only one wins.

War of attrition

Animals invest (b1,b2) in fighting.Maynard Smith, J. (1974) Theory of games and the evolutionof animal conflicts.

AGT-MIRI Single item auctions

Page 187: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

All-pay auctions: examples

crowdsourcing over the internet:

First person to complete a task for me gets a reward.A group of people invest time in the task. (=payment)Only the winner gets the reward.

Advertising auction:

Collect suggestion for campaigns, choose a winner.All advertiser incur cost of preparing the campaign.Only one wins.

War of attrition

Animals invest (b1,b2) in fighting.Maynard Smith, J. (1974) Theory of games and the evolutionof animal conflicts.

AGT-MIRI Single item auctions

Page 188: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

All-pay auctions: examples

crowdsourcing over the internet:

First person to complete a task for me gets a reward.A group of people invest time in the task. (=payment)Only the winner gets the reward.

Advertising auction:

Collect suggestion for campaigns, choose a winner.All advertiser incur cost of preparing the campaign.Only one wins.

War of attrition

Animals invest (b1,b2) in fighting.Maynard Smith, J. (1974) Theory of games and the evolutionof animal conflicts.

AGT-MIRI Single item auctions

Page 189: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

All-pay auctions: examples

crowdsourcing over the internet:

First person to complete a task for me gets a reward.A group of people invest time in the task. (=payment)Only the winner gets the reward.

Advertising auction:

Collect suggestion for campaigns, choose a winner.All advertiser incur cost of preparing the campaign.Only one wins.

War of attrition

Animals invest (b1,b2) in fighting.Maynard Smith, J. (1974) Theory of games and the evolutionof animal conflicts.

AGT-MIRI Single item auctions

Page 190: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

All-pay auctions: examples

crowdsourcing over the internet:

First person to complete a task for me gets a reward.A group of people invest time in the task. (=payment)Only the winner gets the reward.

Advertising auction:

Collect suggestion for campaigns, choose a winner.All advertiser incur cost of preparing the campaign.Only one wins.

War of attrition

Animals invest (b1,b2) in fighting.Maynard Smith, J. (1974) Theory of games and the evolutionof animal conflicts.

AGT-MIRI Single item auctions

Page 191: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

All-pay auctions: examples

crowdsourcing over the internet:

First person to complete a task for me gets a reward.A group of people invest time in the task. (=payment)Only the winner gets the reward.

Advertising auction:

Collect suggestion for campaigns, choose a winner.All advertiser incur cost of preparing the campaign.Only one wins.

War of attrition

Animals invest (b1,b2) in fighting.Maynard Smith, J. (1974) Theory of games and the evolutionof animal conflicts.

AGT-MIRI Single item auctions

Page 192: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue

At equilibrium neither SP nor FP lead the maximum possiblebenefit to the seller.

Can we get a better understanding of revenue?

Can we have a truthful auction giving maximum revenue?

AGT-MIRI Single item auctions

Page 193: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue

At equilibrium neither SP nor FP lead the maximum possiblebenefit to the seller.

Can we get a better understanding of revenue?

Can we have a truthful auction giving maximum revenue?

AGT-MIRI Single item auctions

Page 194: An introduction to Mechanism design: Single Item Auctionsmjserna/docencia/agt-miri/17/AGT7-auction… · Mechanism design Auctions:Context and De nitions Single item auctions Analyzing

Mechanism designAuctions:Context and Definitions

Single item auctionsAnalyzing auctions

Revenue in auctions

Maximal revenueSP auctionsFP auctionsRevenue equivalenceAll-pay auctions

Revenue

At equilibrium neither SP nor FP lead the maximum possiblebenefit to the seller.

Can we get a better understanding of revenue?

Can we have a truthful auction giving maximum revenue?

AGT-MIRI Single item auctions