Author: Scott Gasch
Date: 08:42:07 07/23/99
Hi. I have implemented hashing (transposition) tables based on crafty's code and some posts about it here. It makes sense and works very well... but I am having trouble with one aspect of it. In a position where the side on move has a very good move (promote a pawn, capture a queen, etc) I am hitting the hash table at every depth of my search and the table is returning a bound instead of an exact score. This happens, for example, on plys 1 through 6. The program then begins to search ply 7 but runs out of time. Since plys 1-6 were bounds from the hash, I have no move at this point. I return NULL from the search routine and the program asserts when I try to make the move! I thought about not hitting the hash after a certain depth but this seems like a bad idea because who knows what the time controls will be and how long the program has given itself to think? Is there a solution to this problem? Is this problem a result of me not implementing the hash correctly? Thanks again for all the help, Scott
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