Abstract
There are two kinds of games, a game with perfect information and a game with imperfect information. In the study on a game with perfect information such as Shogi, Chess, strong computer programs of Shogi, Chess have been developed, which win a world champion or are as strong as amateurs with grade holders. On the other hand in the study on a game with imperfect information such as poker, contract bridge, strong algorithms are not developed yet since assessment of the strength of a hand and opponent strategy using imperfect information has much uncertainty. This paper takes a Seven card Stud Poker game as a game with imperfect information and aims at the construction of its playing system. The present system has fuzzy rules with non-fixed consequent parts and with threshold values in order to make decisions according to opponent strategy. The threshold values are changed according to opponent strategy during the game. The system is a decision making system that assesses superiority/inferiority of its own hand, and makes decisions whether it drops or not and how much it bets in a game by the fuzzy inference using these irregular fuzzy rules. The usefulness of the system is discussed by analyzing data obtained in experiments, in which the present system plays a stud poker game with human players.
