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Lecture Notes

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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)