The Structure of Networks
with emphasis on information and social networks
RU T-214-SINE
Summer 2011
Ýmir Vigfússon
Logistics (1/2)
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The course will be taught in English
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Weekdays 16:35-18:10 from 4/7-12/8
◦ Fridays reserved to be recitation sections
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Office hours: Monday 12:00-13:00, V.3.06
◦ Or by appointment (e-mail me)
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Prerequisites
◦ Discrete Mathematics (or comparable background)
◦ Inherent curiosity, thirst for knowledge and
challenges
Logistics (2/2)
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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.
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Collaboration advised and encouraged!
◦ Final exam closed book
◦ You are expected to maintain academic integrity
according to RU regulations
Evaluation
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Homework 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 presentation
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Final exam (40%)
◦ 90 minute closed-book in-class exam on 12/8.
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In-class participation (10%)
◦ You should be asking questions and making the
experience interactive.
◦ Remote students should participate via threads (or
Skype)
Food for thought
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The book is awesome
◦ We will read most of it
◦ That‘s a lot of pages, be sure to read as you go!
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You can push the envelope
◦ Do you have access to cool network data? Why
not turning that into a project?
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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 everywhere
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Modern society is “connected“ in
different ways
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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
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34 person Karate club
◦ Nodes are people, edges are friendship
Network science - examples
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E-mail communication patterns within HP
◦ Superimposed on the company hierarchy
◦ 436 employees
Network science - examples
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Loans among financial institutions
◦ Which institutions are powerful?
Questions we will explore
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What are the structural features of
networks?
◦ Hard to eyeball features of large networks
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Can we reason about behavior and
interaction in networks?
◦ Strategic incentives, cause-and-effect
relationships
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What are the dynamics of aggregate
behavior?
◦ Why are YouTube and Facebook so popular?
◦ How do things go viral?
Our plan of attack (1/2)
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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.
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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
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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)
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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)
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Week 5: 1/8-5/8 [ch 19-21]
◦ Network cascades. Small world effect. Epidemics.
◦ 2/8: Group progress report due (1 page)
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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 Bacon
A movie to tantalize your taste buds
 Gives an idea about the types of problems
network scientists work on
 Key concepts
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Six degrees of separation
Degree distributions
Power laws
Epidemics over networks