Author: Bas Hamstra
Date: 15:33:43 09/05/04
Go up one level in this thread
On September 05, 2004 at 11:47:42, Stuart Cracraft wrote: >On September 04, 2004 at 18:30:36, Uri Blass wrote: > >>On September 04, 2004 at 18:20:49, Stuart Cracraft wrote: >> >>>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 >> >>If your qsearch can call the main search then it is clear that 3 is not useful >>because your search will explode by the following sequence: >> >>1.Qsearch checking move first ply >>2.main search escape from check. >>3.Qsearch checking move first ply because it is a new qsearch. >>4.main search escape from check. >>... >> >>If you want to use checks in the first ply of the qsearch then the qsearch >>should never call the main search. >> >>Uri > >Uri, > >I should try tinkering with a qsearch that, if in check upon entry, simply >generates check avoidance moves internally. > >Thanks, > >Stuart Hi Stuart, Yes, only then will you see the merits, I think... And you *will* crack Wac141 (and alike). Bas.
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