情報と意思決定 : ゲーム論的分析 Information and Decision Making : A Game Theoretic Approach
Information plays an important role in social and economic situations where decision makers with different interests are interdependent. From a game theoretic point of view, we investigate the problems of information such as how information affects the behavior of each decision maker, whether information is profiable for decision makers or not, and what the value of information is. The paper consists of the following sections : (1) Introduction, (2) The form of a game and its solution concept, (3) The information structures and the equilibrium points, (4) The value of information, (5) Concluding remarks. In Section 2, we present the extensive form of a game and define the concept of a (Nash) equilibrium point. In Section 3, developing the well-known Kuhn's theorem, we show that in the class of games with perfect recall a game is determinate, i.e., has at least one equilibrium point in pure strategies if and only if it has perfect information. In Section 4, the basic result on the value of information is stated, which says that private information is always profitable for a player in zero-sum two-person games. We also provide an example of a non-zero-sum two-person game in which the value of private information is negative.
社会・経済システム 3(0), 32-36, 1985