The Structure of Networkswith emphasis on information and social

networks

RU T-214-SINE Summer 2011

Ýmir Vigfússon

Logistics (1/2)The course will be taught in English

Weekdays 16:35-18:10 from 4/7-12/8◦Fridays reserved to be recitation sections

Office hours: Monday 12:00-13:00, V.3.06◦Or by appointment (e-mail me)

Prerequisites◦Discrete Mathematics (or comparable background)◦ Inherent curiosity, thirst for knowledge and

challenges

Logistics (2/2)Course material

◦Networks, Crowds and Markets (Easley, Kleinberg 2010). Also available online!

◦Supplementary slides/documents/demos on MySchool

◦Lectures will be recorded and posted online.

Collaboration advised and encouraged!◦Final exam closed book◦You are expected to maintain academic

integrity according to RU regulations

EvaluationHomework assignments (50%)

◦ Two problem sets (10%, 15%) Mostly questions from the book Fully understand and critically evaluate a real scientific

paper◦ Large group project (25%)

Evaluate a real data set, try to advance the state of the art!

Progress report required and a final presentationFinal exam (40%)

◦ 90 minute closed-book in-class exam on 12/8.In-class participation (10%)

◦ You should be asking questions and making the experience interactive.

◦ Remote students should participate via threads (or Skype)

Food for thoughtThe book is awesome

◦We will read most of it◦That‘s a lot of pages, be sure to read as you

go!You can push the envelope

◦Do you have access to cool network data? Why not turning that into a project?

The field is young and emerging◦Tons of opportunities for high impact projects◦ I am always looking for talented students –

let‘s talk if you have interesting ideas!◦Exciting group projects could be further

developed to become publications!

Networks are everywhereModern society is “connected“ in

different ways◦Global communication◦The Internet◦Social networks◦Financial systems◦News and media

Network science◦“The study of phenomena that take

place within complex social, economic and technological systems.“

Network science – examples

34 person Karate club◦Nodes are people, edges are friendship

E-mail communication patterns within HP◦Superimposed on the company hierarchy◦436 employees

Network science - examples

Network science - examples

Loans among financial institutions◦Which institutions are powerful?

Questions we will exploreWhat are the structural features

of networks?◦Hard to eyeball features of large networks

Can we reason about behavior and interaction in networks? ◦Strategic incentives, cause-and-effect

relationshipsWhat are the dynamics of

aggregate behavior?◦Why are YouTube and Facebook so

popular?◦How do things go viral?

Our plan of attack (1/2)Week 1: 4/7-8/7 [ch 1-3,5]

◦Intro. Basic graph theory. Theory of weak ties.◦4/7: PS1 (done in pairs) out.

Week 2: 11/7-15/7 [ch 6-8,9]◦Structural balance. Game theory. (Auctions)◦11/7: Group project out (teams of 4)◦15/7: PS1 due

Week 3: 18/7-22/7 [ch 13-15]◦The Web. PageRank. Sponsorsed search

markets.◦18/7: PS2 (done in different pairs) out.

Our plan of attack (2/2)Week 4: 25/7-29/7 [ch 16-18]

◦Cascades. Network effects. Power laws.◦27/7: PS2 due.◦27/7-1/8: Ýmir away (more info later)

Week 5: 1/8-5/8 [ch 19-21]◦Network cascades. Small world effect. Epidemics.◦2/8: Group progress report due (1 page)

Week 6: 8/8-12/8 [ch 22,23,24]◦Voting theory. (Markets). ◦10/8: Group project presentations (20 min)◦12/8: Final exam in-class (individual).

Six degrees of Kevin BaconA movie to tantalize your taste

budsGives an idea about the types of

problems network scientists work on

Key concepts◦Six degrees of separation◦Degree distributions◦Power laws◦Epidemics over networks