Author: milix
Date: 23:55:48 02/17/04
Hi to everyone! In my amateur engine I encounter a really nasty hash table related bug. A hash element contained a position and a best move, say Ra8-a4. When this position occured again in a search, the rook was not on a8 but on a2. So the right best move should be Ra2-a4. So, I added a routine to check for such 'corrupted' hash moves. I currently solve the above mentioned problem by looking at legal moves in the position that had a move with the best's move 'to' square and is moving the best's move piece. This correction is only done when I retrieve the PV from the hash table, so it is practically cheap. I have one question about the above concept: Is this happen to every hash table or I have a pathological situation which may (or may already have) introduce other bugs? My hash table uses the replace always scheme and is cleared only at the start of a new game.
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