doubledummytechniek

Double Dummy Technique (Dutch: doubledummytechniek) is a method in contract bridge for evaluating the maximum number of tricks that can be won from a given four-handed deal when the exact distribution of all cards is known. It treats the problem as a perfect-information search, considering every possible line of play by declarer and by the defenders to identify the optimal sequence of plays.

In practice, double dummy analysis is used to solve bridge problems, study endgames and squeezes, and test the strength of play strategies. It can be performed manually for simple layouts, but is typically carried out with computer programs or formal analysis because the number of possible plays grows rapidly with the size of the deal.

Important caveats apply: the results reflect what is theoretically possible under perfect information, not what would occur in a real game where players do not know all unseen cards. Real play is constrained by bidding, tempo, and imperfect information. Nevertheless, the double dummy count provides an upper bound for declarer tricks and a lower bound for defender tricks in many situations, serving as a useful benchmark for evaluation.

Origin and usage: the concept gained prominence with the development of problem-solving literature and computer analysis in bridge from the mid- to late 20th century and is now standard in bridge software, training materials, and analytical discussions. It underpins many endgame studies and helps researchers and players understand optimal lines of play under full information.

See also: contract bridge, double dummy analysis, endplay, bridge software.