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Ehud Kalai is a prominent American game theorist and mathematical economist known for his contributions to game theory and its interface with economics, social choice, computer science and operations research. He is the James J. O'Connor Distinguished Professor of Decision and Game Sciences at Northwestern University, where he has taught since 1975.

Kalai moved from Israel to the US in 1963. He received his AB in mathematics from the University of California Berkeley (1967) and an MS (1971) and a PhD (1972) in statistics and mathematics from Cornell University. After serviing as an assistant professor of statistics at Tel Aviv University (1972-1975), he was hired by Northwestern University to establish a research group in game theory. He is the founding director of the Kellogg Center of Game Theory and Economic Behavior and the executive director of the Nancy L. Schwartz Memorial Lecture series.

Kalai is the found Editor of Games and Economic Behavior, the leading journal in game theory. With Robert J. Aumann, Kalai founded the Game Theory Society and served as its president from 2003 to 2006. He is a Fellow of the American Academy of Arts and Sciences and of the Econometric Society, was awarded an Honorary Doctorate by the University of Paris (2010), the Sherman Fairchild Distinguished Scholar position at the California Institute of Technology (1993), and was appointed the Oskar Morgenstern Research Professor at New York University (1991).

Selected Contributions:

In cooperative game theory, the Kalai-Smorodinsky solution reopened the study of bargaining by showing that the long unchallenged Nash solution is not unique. He later axiomatized the Egalitarian solution to bargaining problems and, with D. Samet, formulated its extension to general (NTU) cooperative games, unifying it with the Shapley (TU) Value.

In non cooperative game theory, the Kalai-Lehrer model of rational learning showed that rational players with truth-compatible beliefs eventually learn to play Nash equilibria of repeated games. In particular, in Bayesian equilibria of repeated games all relevant private information eventually becomes common knowledge.  Kalai's work on large games showed that the equilibria of Bayesian games with many players are structurally robust, thus large games escape major pitfalls in game-theoretic modeling.

Kalai is also known for seminal collaborative research on flow games and totally balanced games; strategic complexity and its implications in economics and political systems; arbitration, strategic delegation and commitments; extensions of Arrow’s Impossibility Theorem in social choice; competitive service speed in queues; and on rational strategic polarization in group decision making.

Selected Publications:

Cooperative Game Theory
"Other Solutions to Nash's Bargaining Problems," Econometrica, 1975 (with M. Smorodinsky)
"Proportional Solutions to Bargaining Situations: Interpersonal Utility Comparisons," Econometrica, 1977
"Monotonic Solutions to General Cooperative Games," Econometrica, 1985 (with D. Samet)

Non cooperative Game Theory
"Finite Rationality and Interpersonal Complexity in Repeated Games," Econometrica, 1988 (with W. Stanford)
"Rational Learning Leads to Nash Equilibrium," Econometrica, 1993 (with E. Lehrer)
“Large Robust Games,” Econometrica, 2004

Probability and Learning

"Bayesian Representations of Stochastic Processes Under Learning: deFinetti Revisited," Econometrica, 1999 (with M. Jackson and R. Smorodinsky)


"The Kinked Demand Curve, Facilitating Practices, and Oligopolistic Coordination," 1986 Northwestern DP (with M. Satterthwaite; published by Kluwer, 1996))
"Observable Contracts: Strategic Delegation and Cooperation," International Economic Review, 1991 (with C. Fershtman and K. Judd)
"Complexity Considerations in Market Behavior," The RAND Journal of Economics, 1993 (with C. Fershtman)

Social Choice

"Aggregation Procedure for Cardinal Preferences: A Formulation and Proof of Samuelson's Impossibility Conjecture," Econometrica, 1977 (with D. Schmeidler)
"Characterization of Domains Admitting Non-Dictatorial Social Welfare Functions and Non-Manipulable Voting Procedures," Journal of Economic Theory, 1977 (with E. Muller)
"Path Independent Choices," Econometrica, 1980 (with N. Megiddo)

Operations Research / Computer Science

"Totally Balanced Games and Games of Flow," Mathematics of Operations Research, 1982 (with E. Zemel)
"Optimal Service Speeds in a Competitive Environment," Management Science, 1992 (with M. Kamien and M. Rubinovitch)
“Partially-Specified Large Games,” Lecture Notes in Computer Science, 2005

Mathematical Psychology
"Strategic Polarization," Journal of Mathematical Psychology, 2001 (with A. Kalai)

Center for Strategic Decision Making
Games and Economic Behavior
Game Theory Society
Professor Kalai's Kellogg Page