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The first version of LChess was written in 1987. In 1988 it participated for the first time in the Dutch Computer Chess Championship, ending 13th in a field of 16; the best result was in 1990 when it ended on a shared 3rd place. Lex Loep has steadily worked on the chess engine and the version which is playing in the WCCC has been ported to Windows NT. Techniques used by the chess engine include [[Alpha-Beta|alpha-beta]] search, [[Iterative Deepening|iterative deepening]], [[Principal Variation Search|PVS]], [[Null Move|null moves]] for [[Null Move Pruning|pruning]] and [[Null Move Pruning#ThreatDetection|thread detection]], [[History Heuristic|history tables]], [[Killer Heuristic|killer heuristics]], [[Transposition Table|transposition tables]] and [[Refutation Table|refutation tables]]. Tactically the program plays very well, and is particularly good in finding mate threads. Positionally there is still a lot of work to do. On the Reinfeld test set it scores more than 80% with 1 minute CPU time on a [[x86|Pentium 90]]. Search speed is 30,000 - 50,000 [[Nodes per secondSecond|nodes/second]]. [[Ger Neef]] wrote the user interface.