How expensive a logical agent

is?

Logical Agent

Common Sense

A program has common sense if it automatically deduces for itself

a sufficiently wide class of immediate consequences of anything it is told and what it

already knows

John McCarthy

• 1955: Develop the phrase

“Artificial Intelligence”

• 1959: Programs with

Common Sense

• 1960: First LISP

implementation

• 1971: Turing Award

Recipient

Intelligent SystemCore Features:

1. Representation of all the behaviors.

2. Interesting changes in behavior must be

expressible in a simple way.

3. All the aspects of behavior must be improvable.

4. Need of partial success concepts.

5. Need to have subroutines which can be

included in procedures as units.

Intelligent SystemCore Features:1. Representation of all the behaviors.

2. Interesting changes in behavior

must be expressible in a simple way.

3. Improving mechanism should be improvable.

4. Need of partial success concepts.

5. The system must be able to create subroutines which can

be included in procedures as units.

Advice Taker• Is a proposed program for solving problems

by manipulating sentences in formal

languages.

• The basic program will draw immediate

conclusions from a list of premises.

• These conclusions will be either Declarative

or Imperative sentences.

Sentence

Imperative SentenceDirect InstructionsEg: “Go to the car and drive

to the airport! “

Declarative SentenceDescription of a situationEg: “I want to go to the

airport”

What is NOT Advice Taker?

• Heuristics are NOT embodied in the

program

• Procedures and heuristics are

described in the language itself

Advice taker• An example:

• Assume that I am seated at my desk at home

and I wish to go to the airport.

• My car is at my home also.

• The solution of the problem is to walk to the

car and drive the car to the airport.

Some Premises we can make..

A predicate “at”“at(x,y)” is a formalization of “x is at y”

Some rules we can embed..

Deduction• Deduction Process• According to

• x: home, y: desk, z: car• We can deduce

Ambiguities• Semantics of the language Meaning of “at” is controversial• Can have multiple syntactically correct but

semantically incorrect inferences towards the same goal.

Inference algorithms

• Building models (finite models)

• Resolution

• Factoring

Time complexity

• Even an inference algorithm is meant to be sound and complete this may take an exponential time even in well defined finite state environments.

Can we match a logic agent to a human

• We can’t make a generalized inference in a constant time in which most of the human beings are capable of

Thank You!

• Dileepa Fernando• Rashmika Nawaratne

Clarifications ?

The Present…• The symposium on common sense

reasoning held at The Courant Institute – 2001

1. Better sense of how to develop a workable methodology for formalizing common sense

2. How to divide the larger problem up into more manageable parts

Why this subject is difficult?

Simple tasks use implicit assumptions which cannot be determined without proper (deep) study about human mind.

• Real world Example:

• Research paper: