Author: Uri Blass
Date: 13:18:43 10/24/05
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On October 24, 2005 at 15:41:34, Tord Romstad wrote: >On October 24, 2005 at 14:09:30, K. Burcham wrote: > >>Are there any programs that you know of, that clears hash between moves with the >>default settings? > >I don't think so. Clearing the hash table between moves is simply a very bad >idea. It reduces the efficiency of the search and introduces some overhead >(clearing a big chunk of memory is a time-consuming operation) without any >advantages whatsoever (at least as far as I can see). > >On the other hand, there are many programs (including mine) which don't >use hash entries from the previous search for pruning. The old hash entries >are only used for move ordering. > >Tord As far as I know Chessmaster clears the hash tables between moves. Movei also do it usually except cases when it has little time relative to the hash tables(I do not remember the exact rules now) The reason for Movei to clear the hash tables between moves is that Movei use a stupid replacement scheme of replacing only when the depth is bigger so if I do not clear hash between moves I may remain with old entries that are useless. I did not like changing it to replace always because I remember based on experience that at long time control it was worse and I also think about rewriting Movei(no promise if it is going to happen) and I did not like trying to fix my old hash code. Uri
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