Events Calendar

Learning and Coordination In Social Networks

Speaker: Ali Jadbabaie, University of Pennsylvania

Talk Title: Learning and Coordination In Social Networks

Abstract: In the first part of this talk we examine how the structure of a social network and the quality of information available to different agents affects social learning and information aggregation. To this end, we study a variant of the seminal model of DeGroot, according to which agents linearly combine their personal experiences with the views of their neighbors. We show that the rate of learning has a simple analytical characterization in terms of the relative entropy of agents' signal structures and their eigenvector centralities. Our characterization establishes that the way information is dispersed throughout the social network has non-trivial implications for the rate of learning. In particular, we show that when the informativeness of different agents' signal structures are comparable, positive assortative matching of signal qualities and agent centralities maximizes the rate of learning. On the other hand, if information structures are such that each individual possesses some information crucial for learning, and the information endowments are not comparable, then the rate of learning is higher when agents with the best signals are located at the periphery of the network. Finally, we show that the extent of asymmetry in the structure of the social network plays a key role in the long-run dynamics of the beliefs.

In the second part, we introduce and analyze a novel model of opinion formation according to which agents not only seek to discover the truth but also have the tendency to act in conformity with the rest of the population. Such preferences for conformity are relevant in scenarios ranging from participation in popular movements to trading in stock market. We argue that agents who value conformity do not necessarily fully aggregate the dispersed information; nonetheless, we prove that examples of the failure of information aggregation are rare in a precise sense.


Biography: Ali Jadbabaie received his BS degree with High honors in Electrical Engineering (with a focus on Control Systems) from Sharif University of Technology, Tehran, Iran, in 1995. After a year of working as a control engineer, he moved to the US where he received a Masters degree in Electrical and Computer Engineering from the University of New Mexico, Albuquerque in 1997 and his Ph.D. degree in Control and Dynamical Systems from California Institute of Technology (Caltech) in 2001. From July 2001-July 2002 he was a postdoctoral scholar at the department of Electrical Engineering at Yale University. Since July 2002 he has been at the University of Pennsylvania, Philadelphia, PA, where he is currently The Alfred Fitler Moore Professor of Network Science in the department of Electrical and Systems Engineering with secondary appointments in departments of Computer & Information Sciences and Operations and Information Management (in the Wharton School of Management). He is a member of GRASP Laboratory and the director of the Raj and Neera Singh Program in Networked and Social Systems at Penn Engineering, a new interdisciplinary undergraduate degree program at Penn that blends Network Science, Operations Research, Economics, and Computer Science with Information and Decision Systems. He is a recipient of an NSF Career award, a Young Investigator award from the Office of Naval Research, the O. Hugo Schuck Best Paper award of the American Automatic Control Council, and the George S. Axelby Outstanding Paper Award of the IEEE Control Systems Society. His students have won best paper awards at the American Control Conference (ACC) and been award finalists at 3 IEEE CDC and ACC conferences. His research is broadly at the interface of systems and control theory with optimization and network science with focus on analysis, design and optimization of networked dynamical systems in a variety of applications including sensor networks, multi-robot formation control, opinion aggregation, and strategic interaction in social networks.

Host: Urbashi Mitra, ubli@usc.edu, EEB 536, x04667

Location: Hughes Aircraft Electrical Engineering Center (EEB) - 248

Audiences: Everyone Is Invited

Contact: Gerrielyn Ramos