SUMMARYThe auction in contract bridge is a game with incomplete information. This paper models the process as an interaction among agents with a hypothetical reasoning mechanism. The criterion for the action of each agent is defined as "maximizing gain by cooperating with the partner and minimizing loss by competing with the opponents." An agent with the following characteristics is created. Based on the course of bidding, the hands of both sides are estimated by hypothetical reasoning. Then flexible bids are made in an effort to obtain the contract with the greatest gain or smallest loss of points. Experiments show that in a game with incomplete information, it is useful not only to send information to the partner, but also to disrupt information exchange by the opponents. The effect of ambiguity of information on the behavior of both sides is discussed.

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In order to develop a computer bridge system that can play on an equal basis with the expert, various problems which are inherent to the incomplete information game must be solved. The authors intend to develop a new problem‐solving technique through the challenge of computer bridge. In the bidding process in bridge, the player makes an effort to arrive at a better contract through collaboration involving the exchange of information by restricted bids. This paper reports a framework which was devised aiming at more humanlike (flexible) bidding than past programs. As the first step, the partnership in the bidding process is modeled as a communication between two agents with common knowledge and hypothetical reasoning mechanisms. The knowledge is divided into expertise and common sense, and a bid of the partner which deviates from the former is handled by the latter. In inferring the hand of the partner, the partner's conception of the player's own hand is also estimated, and a more adequate hypothesis is posed. As a result, a program that can perform flexible bidding according to the response of the partner is constructed. © 2000 Scripta Technica, Syst Comp Jpn, 31(2): 72–82, 2000

SUMMARYIn order to develop a computer bridge system that can play on an equal basis with the expert, various problems which are inherent to the incomplete information game must be solved. The authors intend to develop a new problem-solving technique through the challenge of computer bridge. In the bidding process in bridge, the player makes an effort to arrive at a better contract through collaboration involving the exchange of information by restricted bids. This paper reports a framework which was devised aiming at more humanlike (flexible) bidding than past programs. As the first step, the partnership in the bidding process is modeled as a communication between two agents with common knowledge and hypothetical reasoning mechanisms. The knowledge is divided into expertise and common sense, and a bid of the partner which deviates from the former is handled by the latter. In inferring the hand of the partner, the partners conception of the players own hand is also estimated, and a more adequate hypothesis is posed. As a result, a program that can perform flexible bidding according to the response of the partner is constructed.