Lecture Notes

The actual size of these slides is 12.8 cm by 9.6 cm. Use Adobe Reader's print options to scale the slide to fit the page before printing.

Lecture files.
SES #	TOPICS	SLIDES
1	Introduction to economic, social, and communication networks	Lecture 1 (PDF - 1.0MB)
2	Graph theory and social networks Directed and undirected graphs, paths, cycles, diameter, clustering, bipartite graphs. Applications: the web as a directed graph, graphical representation of homophily	Lecture 2 (PDF)
3-4	Branching processes and random graph models Review of branching processes, Erdös-Renyi graphs, degree distributions, phase transitions, connectedness, and giant component. Applications: tipping, six degrees of separation, and disease transmissions	Lecture 3 (PDF) Lecture 4 (PDF)
5-7	Rich get richer phenomena, power laws, and small worlds Preferential attachment, degree distributions, generalized random graphs, and clustering. Applications: firm size distributions, link analysis and web search, PageRank, decentralized search, and navigation	Lecture 5 (PDF) Lecture 6 (PDF) Lecture 7 (PDF)
8	Epidemics and diffusion through networks SIR (susceptible, infected, removed) and SIS (susceptible, infected susceptible) models of diffusion. Applications: spread of information and disease, and genetic inheritance	Lecture 8 (PDF)
9-11	Introduction to game theory Games, strategies, payoffs, extensive and normal forms, and Nash equilibrium. Applications: tragedy of the commons and coordination games	Lecture 9 (PDF) Lecture 10 (PDF) Lecture 11 (PDF)
12	Applications of game theory to networks Modeling network traffic, strategic network formation, negative externalities, Braess' paradox, and potential games. Application: congestion tax in London	Lecture 12 (PDF)
13-14	Evolution, learning, and myopia vs. rationality Evolutionary stable strategies, fictitious play, emergence of Nash equilibrium from rules of thumb, limits of myopic behavior. Application: rules of thumb in traffic	Lectures 13 and 14 (PDF)
15-16	Dynamic and repeated games, and cooperation and trust in networks Subgame perfect Nash equilibrium, repeated games, prisoners' dilemma, repeated games over networks. Application: emergence of cooperation in social networks	Lecture 15 (PDF) Lecture 16 (PDF)
17-18	Network effects, innovation, tipping and contagion Positive externalities, strategic complements, path dependence, diffusion of innovation, and tipping in technology, financial, and product markets. Application: the rise of Microsoft and contagion phenomena	Lectures 17 and 18 (PDF)
19-21	Games of incomplete information Bayes rule, Bayesian Nash equilibria, first and second price auctions, and introduction to social learning. Applications: spectrum auctions, market for lemons, and keyword-based advertising	Lectures 19 to 21 (PDF)
22-23	Social learning in networks Bayesian learning, benefits of copying, herd behavior, informational cascades. Applications: consumer behavior and financial markets	Lectures 22 and 23 (PDF)
24	Decisions in groups Decision making in organizations and societies, social choice, Condorcet jury theorem, and political economy. Application: committee decisions	Lecture 24 (PDF)