Tatsuro Ichiishi

Tatsuro Ichiishi

Tatsuro Ichiishi

Professor Emeritus



  • Ph.D., University of California, Berkeley, Economics 1974
  • M.A., University of California, Berkeley, Mathematics 1973
  • M.A., Keio University, Economics 1968
  • B.A., Keio University, Economics 1966


My research interests have been in analytical theory of the firm, general equilibrium analysis, game theory, and fixed-point theory. I would like to understand the simultaneous workings of the firm-specific resource allocation mechanism and the (neoclassical) market mechanism. I formulate the former mechanism as the generalized strategic game in which decision-makers can coordinate their strategies.

My early results from this economic investigation include the establishment of an equilibrium existence theorem, where the new equilibrium concept is a solution to simultaneous workings of the firm-specific resource allocation mechanism and the market mechanism. I later extended this line of research to also cover production theory with increasing returns to scale and theory of comparative economic systems.

To solve these economic questions, I pioneered research in cooperative extensions of the noncooperative game, a basic area which serves as a game-theoretical foundation of economic analysis, and looked into the underlying fixed-point theory. Among my early results from the research in cooperative extensions is the establishment of a social coalitional equilibrium existence theorem, which includes Nash's equilibrium existence theorem (the Nash equilibrium is a typical noncooperative solution concept), Scarf's core nonemptiness theorem (the core is a typical descriptive cooperative solution concept) and Arrow-Debreu-McKenzie's competitive equilibrium existence theorem as special cases.

Recently, I have been working on cooperative extensions of the Bayesian game, which is also Bayesian extensions of a cooperative extension of the noncooperative game. One of my notable results in this area is an explanation of how private information is revealed to the public.

Further research on information revelation in (generalized) cooperative games with incomplete information.