UBC Theses and Dissertations
Computer chess tactics and strategy Szabo, Alexander
The design for a chess program is presented. The notions of tactics and strategy are used to define complementary ways of understanding any position. An association is made between tactics and brute force tree searching, and strategy and knowledge encoding. It is claimed that knowledge is best applied at the top of the tree as exemplified by TECH's positional presort rather than at the "terminal nodes using complex evaluation functions. The tactics part of the design is implemented by the program TECH3 which is described in terms of refinements to the minimax algorithm. The refinements are the α-β algorithm, the quiescence search, the transposition table, α-β move ordering, the search depth metric, the depth iterative α-β technique, and aspiration searching or windowing. The simple evaluation function used can also be considered as a refinement to minimax. TECH3's performance on the problems in Reinfeld (1958) is 274/300 which, modulo machine power, compares favourably with BELLE's. A comparison is also made with the knowledge based tactics program, PARADISE. Finally, the technology curve is developed as a tool for measuring the effectiveness of knowledge encoding (or strategy). In this respect NUCHESS is identified as the current best chess program.
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