# 20462 - SOCIAL AND ECONOMIC NETWORKS

**CLMG - M - IM - MM - AFC - CLAPI - CLEFIN-FINANCE - CLELI - ACME - DES-ESS - EMIT**

Course taught in English

Go to class group/s: 31

The course presents the main theoretical developments of the modern field of social networks, as these have been applied to understand some of the most important social and economic phenomena that are central to our highly connected societies.

The emphasis of the course will be on the theory, but we shall also illustrate matters with examples from real--world social networks.

Initially, we shall focus on phenomena such as search, contagion,diffusion, or learning,which can be largely conceived as non--strategic. Then, we shall turn to the study of strategic problems such as congestion , trade, intermediation, power, or bargaining, which display an essential strategic component and thus have to be analyzed using the tools of Game Theory.

Throughout, our main concern will be to develop a formal and systematic manner of understanding how social structure (i.e. the pattern of connections) affect a wide variety of social behavior.

- Graphs: definitions and measures - basic concepts: degree,distance,component,clustering,betweenness,etc.
- Types of networks : lattice,tree/hierarchic,random,etc.
- Some real-world examples . a glimpse into its wide diversity.
- Forces / mechanisms at work:
- Distance / geography.
- Popularity.
- Link strength and intermediation.
- the social environment : homophily and socialization.
- Positive and negative relationships: structural balance.
- Diffusion and search in networks:
- epidemics : contagion processes in a large social nerworks.
- behavioral dynamics : frequency -dependent diffusion.
- Decentralized search in a small world : walking the web.
- Learing in networks : de Groot model.
- Information networks : the World Wide Web ( WWW ):
- Structure of the WWW.
- Web-filtering : centralized search engines & semantic webs.
- Networks and games :Traffic,markets,learning and power:
- Traffic and congestion in networks.
- Matching and markets.
- Intermediation in markets.
- Bargaining and power in networks.

The final grade of the course will be based on the following :

- Regularly assigned problem sets. ( 30%)
- Final exams(70%).

Pre-print copy available at

http://www.cs.cornell.edu/home/kleinber/networks-book/

For a more technical coverage of some of the topics, the following two auxiliary books

can be used:

- F.VEGA-REDONDO, Complex Social Networks , CambridgeUniversity Press, 2007.
- M. JACKSON, Social and Economic Networks , PrincetonUniversity Press, 2008

- Calculus and algebra.
- Dynamical systems.
- Game Theory.