Anyone who has read a number of bridge columns in newspapers will be struck by the frequency with which even the world's top players make mistakes. . . .The key . . . lies in writing a program that can play the cards "perfectly."
– David Levy, from The Million Pound Bridge Program. In Heuristic Programming in Artificial Intelligence: The Second Computer Olympiad. Ellis Horwood Series in Artificial Intelligence. March, 1991.
A computer program that uses AI planning techniques is now the world champion computer program in the game of Contract Bridge. As reported in The New York Times and The Washington Post, this program--a new version of Great Game Products' The classical approach used in AI programs for games of strategy is to do a game tree search using the well-known minimax formula (eq. 1) The minimax computation is basically a bruteforce search: If implemented as formulated here, it would examine every node in the game tree. In practical implementations of minimax game tree searching, a number of techniques are used to improve the efficiency of this computation: putting a bound on the depth of the search, using alpha-beta pruning, doing transposition-table lookup, and so on. However, even with enhancements such as these, minimax computations often involve examining huge numbers of nodes in the game tree. Because a Bridge hand is typically played in just a few minutes, there is not enough time for a game tree search to search enough of this tree to make good decisions.
The card game bridge is a sport and should be exempt from VAT, according to an opinion by the top adviser to the European Court of Justice. In an ongoing case brought by the English Bridge Union, advocate-general Yves Bot said it was a sport because it required mental effort as part of a challenge. HM Revenue and Customs had refused to reimburse the English Bridge Union for VAT payments on entry fees to tournaments. EU law requires proof of benefits to physical or mental well-being for a sport to claim VAT exemption.
Bridge Baron is a computer program that plays bridge. It won the 1997 world championship of computer bridge, the Baron Barclay World Bridge Computer Challenge, as reported in The New York Times and The Washington Post. The five-day competition, which was hosted by the American Contract Bridge League in July 1997, included five computer programs, from the US, Japan, and Germany. The Bridge Baron won every head-to-head match that it played against the other programs.
A computer program that uses AI planning techniques is now the world champion computer program in the game of Contract Bridge. As reported in The New York Times and The Washington Post, this program -- a new version of Great Game Products' BRIDGE BARON program -- won the Baron Barclay World Bridge Computer Challenge, an international competition hosted in July 1997 by the American Contract Bridge League. It is well known that the game tree search techniques used in computer programs for games such as Chess and Checkers work differently from how humans think about such games. This article gives an overview of the planning techniques that we have incorporated into the BRIDGE BARON and discusses what the program's victory signifies for research on AI planning and game playing.