Author: Uri Blass
Date: 08:20:23 09/05/04
Go up one level in this thread
On September 05, 2004 at 11:16:31, Uri Blass wrote: >On September 05, 2004 at 11:02:17, Ed Schröder wrote: > >>On September 04, 2004 at 17:22:40, Uri Blass wrote: >> >>>On September 04, 2004 at 17:06:50, Chris Welty wrote: >>> >>>>On September 04, 2004 at 17:01:40, Uri Blass wrote: >>>> >>>>>Movei does not use hash for pruning. >>>>> >>>>>Uri >>>> >>>>Interesting. Why not? >>> >>>I believe that using hash for pruning limit my possibiloities for improvement >>>with evaluation that is not dependent only on the leaf position and at this time >>>there are more important things to do then using hash for pruning. >> >>Excuse my ignorance but what is hash pruning? >> >>My best, >> >>Ed > >It is what almost every program is using. >It is returning value based on hash tables because the position was already >searched in the past with bigger or equal depth. > >Movei is not using it and it is using hash tables only for order of moves and I >believe that it enable more possibilities for evaluation that is not based only >on the leaf position(for example movei can detect a lot of perpetual checks >without seeing the draw because it's evaluation suspect the draw after a lot of >checks so it gets closer to 0 when other programs cannot do it. > >Of course detecting perpetual check faster is not the only idea that it can be >used for. > >Uri I can add that other programs also return 0 after a lot of checks and I read about modified crafty that returns 0 after more than 10 checks but I think that it is dangerous to do it when the program use hash for pruning because the program may get more than 10 checks in some line that is not optimal and remember 0 in the hashtable and use that value later to evaluate draw in another position. Uri
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