Author: Uri Blass
Date: 12:53:13 08/30/04
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On August 30, 2004 at 15:34:22, Stuart Cracraft wrote: >On August 30, 2004 at 12:21:01, Uri Blass wrote: > >>On August 30, 2004 at 07:36:45, Volker Böhm wrote: >> >>>Hi Uri, >>> >>>do you allways check all evades in qsearch or only until a certain ply as for >>>checking moves? >>> >>>Greetings Volker >> >>only until a certain ply but that ply is late. >>I also do not check all captures and do it only until a certain ply. >> >>I practically have 2 functions of qsearch >>int Quies(int alpha, int beta,int depth) >> >>int quiesmall(int alpha,int beta,int depth) >> >>Quies search checks and captures and when the depth is small enough Quies calls >>quiesmall (quiesmall does not make checking moves that are not captures but it >>calculate all replies to check unless the remaining depth is small enough and >>when the remaining depth is 0 even captures are not tried. >> >> >>Quies usually starts with depth=7 when depth=5 I call quiesmall and when >>depth<=2 I do not generate replies to check and when depth=0 I do not make more >>captures and retrun static evaluation+pawn with the idea that the side to move >>may earn something by a capture but I do not know how much. >> >>It may be better to use static exchange evaluator but it is not very important >>and most qsearch do not get to the place when depth=0 or the result of the >>evaluation when depth=0 is not important for the final score. >> >> >>Uri > >So for all the trouble you have gone to to do all of the above, can you >point at specific measurable achievements you have gained from it? > >Stuart I know that checks in the first plies of the qsearch improved the strength of movei(the improvement was obvious in test suites and I believe that it also helped in games but I did not play enough games to test it) I remember that a buggy implementation that could return wrong mate scores did not change much the strength in games and I later fixed bugs. I think that the main improvement was that after adding checks in the qsearch I changed null move with R=2 to null move with R=3 and R=3 was obviously better with checks in the qsearch(I did not check without them but I read or got the impression that other programs found that R=3 is better with checks in the qsearch when R=2 or E=2/3 is better without them). limiting the qsearch was always part of movei because I did not want the search to explode in Leonid'a positions when both sides have many queens. Movei has problems to go deep in Leonid's position but it has no problem of needing an hour to find mate in 1 that happened to Fritz in one similiar position that was discussed here(Leonid usually gave harder problems than mate in 1). Uri Uri
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