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Microeconomic Theory Workshop: Fedor Sandomirskiy

Tuesday, December 1, 2020 at 12:00pm to 1:00pm

Virtual Event

Fedor Sandomirskiy, Technion (Haifa, Israel)

On social networks that support learning (joint w/Itai Arieli & Rann Smorodinsky)

Abstract: It is well understood that the structure of a social network is critical to whether or not agents can aggregate information correctly. In this paper, we study social networks that support information aggregation when rational agents act sequentially and irrevocably. Whether or not information is aggregated depends, inter alia, on the order in which agents decide. Thus, to decouple the order and the topology, our model studies a random arrival order. Unlike the case of a fixed arrival order, in our model the decision of an agent is unlikely to be affected by those who are far from him in the network. This observation allows us to identify a local learning requirement, a natural condition on the agent’s neighborhood that guarantees that this agent makes the correct decision (with high probability) no matter how well other agents perform. Roughly speaking, the agent should belong to a multitude of mutually exclusive social circles. We illustrate the power of the local learning requirement by constructing a family of social networks that guarantee information aggregation despite that no agent is a social hub (in other words, there are no opinion leaders). Although, the common wisdom of the social learning literature suggests that information aggregation is very fragile, another application of the local learning requirement demonstrates the existence of networks where learning prevails even if a substantial fraction of the agents are not involved in the learning process. On a technical level, the networks we construct rely on the theory of expander graphs, i.e., highly connected sparse graphs with a wide range of applications from pure mathematics to error-correcting codes.

Dial-In Information

If you are interested participating in this seminar, please email Ulrike Kroeller at uab1@cornell.edu for Zoom information.

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Event Type

Seminar, Class/ Workshop

Departments

Economics

Tags

economics, EconSeminar, EconMicro

Contact E-Mail

uab1@cornell.edu

Contact Name

Ulrike Kroeller

Speaker

Fedor Sandomirskiy

Speaker Affiliation

Technion (Haifa, Israel)

Open To

Cornell Economics Community - List Serve Members