ScanDeal

ANALYSIS OF HANDS ScanDeal allows the user to enter bridge deals or puzzles in order to analyse them. It also allows hands to be saved and thus a library to be built up. The program finds the contracts reached in each suit or in no trumps with each of the players as declarer. It determines the best of these contracts and Par for the deal. This is usually done in one or two seconds (exceptionally around ten seconds for very difficult deals, sometimes more). ScanDeal plays the hands, suggesting the best possible plays in each case. The user can replace the program and analyse the hands, manipulating the cards himself. In this case, ScanDeal will inform him of the value of each play and tell him whether it gives tricks to his opponents, and if so how many. Each deal can be played by any player, who can choose any contract. Each puzzle can be played with any player as declarer and any suit as trumps. ScanDeal also offers the possibility of estimating a contract on the basis of a random sample of hidden hands for which the user himself fixes the sample size (the default size is 100). The user can thus obtain an a priori percentage for the success of his contract. With ScanDeal, you can carry out a complete and exact analysis of any deal and any contract. You can thus free yourself from the advice of experts and at the same time you can check their analyses. TECHNICAL The program operates under Windows. If you are using a computer connected to a network or shared between several users you must, as for any operation involving downloading and execution of a program, hold the corresponding permissions. The analysis of the game with the cards visible uses the classic minimax algorithm (Von Neuman, 1929) refined by alpha-beta pruning and its numerous improvements (notably zero window search). The idea of the alpha-beta algorithm was developed independently by several authors during the 1950’s and 60’s. The algorithm was published in 1963 by the Russian Alexander Brudno and subsequently used in chess programs. But it was only with the discovery of partition search by Matthew Ginsberg (1997) that complete analysis of the game became possible (this algorithm was used in the famous GIB program). Ginsberg brought to alpha-beta an improvement of the same order of magnitude that alpha-beta had brought to minimax. The partition research algorithm is described in numerous articles and has given rise to implementations usable in the form of DLLs. ScanDeal uses its own double-dummy solver which develops some specific features, specially in the search of quick tricks (tricks done without losing the hand). Today, with a modern computer, one can analyse an averagely difficult game (that is to say a game where the distribution of the hands is not too eccentric) in some hundredths of a second. With the same computer, using the simple minimax available at the beginning of the 1960’s this analysis would require several times the age of the universe. Each analysis carried out by ScanDeal, involves repeating this operation twenty times to determine the performance of the four players in each of the five trump contracts. The downloaded program works in a demonstration version, or in the complete version if you obtain the key. The demonstration version allows the analysis of 24 famous deals and/or deals typical of particular manoeuvres. These deals have been borrowed from the site: http://perso.orange.fr/herisson.bridgeclub/classic.htm where they are presented and commented. Analysing these deals will allow the user to familiarise himself easily with the program. And also to understand how many plays by champions are based on errors by their opponents...