Author: Stuart Cracraft
Date: 15:20:49 09/04/04
Go up one level in this thread
On August 31, 2004 at 19:43:08, Uri Blass wrote: >On August 31, 2004 at 19:25:39, Stuart Cracraft wrote: > >>On August 30, 2004 at 15:53:13, Uri Blass wrote: >> >>>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 >> >>Uri, >> >>For short searches of 1 second on my box, I've found adaptive null move >>with varying R to give better results than verified null move with R=3. > >Note that I use verified null move pruning only in the endgame and in the >middlegame I use null move pruning with no verification. > >I did not test a lot of possibilities there and I only know that R=3 is >significantly better than R=2 and I also read that people who do checks in the >qsearch tend to prefer R=3(you do not do checks in the qsearch and I mean not to >replies to check). Uri, My program has this in relation to checks, all conditionally compilable: 1) all checks-evasions in quiescence, unlimited occurrences 2) all checks-evasions in main search, unlimited occurrences 3) all checking-moves in quiescence, at the first ply of quiescence These are the three extensions. Only #1 and #2 have proved useful. Stuart
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