Author: Robert Hyatt
Date: 13:06:51 07/23/99
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On July 23, 1999 at 11:42:07, Scott Gasch wrote: >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! How can you do this? The 'bound' can cause a fail high... but then when you increase beta and search again, the bound can't cutoff any longer... Sounds like you are using the probe result incorrectly... > >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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