Author: Stuart Cracraft
Date: 07:29:11 09/03/04
Go up one level in this thread
On September 03, 2004 at 03:15:07, Uri Blass wrote: >On September 03, 2004 at 00:43:27, Stuart Cracraft wrote: > >>So today I find out that my recapture is bad. It must be. Bob said so. >> >>I take 1 minute to reimplement it to be "extend on 2nd capture on the same >>square in a row" because I heard someone else talking about that's the >>way they do it and got a surprise a minute after that. >> >>The result is that Qxf4 for Win-at-Chess comes into view >>in 98 seconds and holds after having been missed after seemingly >>endless runtime with the old bad recapture in or out. > Of course >>it is nothing like the 13,000 nodes that Tord (was it?) solves >>141 in. Perhaps we should have a contest for who solves 141 in >>the fewest moves. > >I see no point for it. > >I am sure that I can solve Qxf4 even in less nodes than tord by adding some >stupid extensions but this is not the target and the target is to play better. > >I discovered that I can solve more positions in the ecmgcp if I reduce my >evaluation based pruning but again it is not the target and the main question is >if I can play better with it. > > He would surely win. It takes me 24 million. >>I admire a search that is so directed in so few nodes. Surely >>we pay homage to Berliner with it, eh? Retire in peace in Florida >>and then two category 4 storms hit. Unlucky fellow. >> >>Alpha=-1182 Beta=-682 Maxdepth=9999999 MaxTime=100000 >> 1/13 g2f1 0.01 -953 945 g2f1 f4d5 >> 2/13 g2f1 0.01 -953 1535 g2f1 f4d5 c1g5 >> 3/15 g2f1 0.02 -953 5010 g2f1 f4d5 c1g5 d5f6 >> 4/23 g2f1 0.09 -953 21387 g2f1 f4d5 b3d5 c6d5 c1c7 d6c7 f1g1 >> 5/25 g2f1 0.65 -953 179404 g2f1 b5b4 b3a4 f4d5 f6g5 d5e7 >> 6/44 g2f1 3.15 -953 728459 g2f1 b5b4 b3a4 f4d5 f6g5 d5e7 >> 7/48> g2f1 64.75 -703 15048349 g2f1 e8c8 f1g1 c8e8 c1b1 f4e2 g1g2 e2d4 >> 7/48 c1f4 98.86 5113 24322991 c1f4 e8e6 f4g5 d7e7 b3e6 e7e6 h1d1 d6e7 >> 8/48< c1f4 98.88 4863 24327933 c1f4 e8e6 f4g5 d7e7 b3e6 e7e6 h1d1 d6e7 >> 8/48 c1f4 108.60 4863 26455348 c1f4 e8e6 f4g5 d7e7 b3e6 e7e6 h1d1 d6e7 >> 9/48> c1f4 159.87 5113 38207334 c1f4 e8e6 f4g5 d7e7 b3e6 e7e6 h1d1 d6e7 >> >>I know my PV is screwy and wonder why Bxf4 isn't played next. Anyone >>know why? To me, Qxf4 followed by Bxf4 and then rook taking along the >>H file looks like the natural PV. I wonder if that is another nasty >>bug lurking. > >No > >After Qxf4 Bxf4 lead to a sinple mate so black has no choice but not to capture. > >If you extend Bxf4 then it is clear than not playing Bxf4 is not extended so >even if both Bxf4 and the alternative are equal you are going to see that Bxf4 >is losing by mate earlier because of extensions. > > I am surprised there can be so many remaining considering >>a fairly decent run-of-the-mill score on WAC 1-300. The set seems to >>have shortcomings. Good for a first year's development effort though. >> >>I am not able to speed 141 up yet with Moreland's Mate Threat Null extension > >If you are not able to see it at smaller ply with mate threat extension then you >must have a bug and I suspect that you have return beta or return alpha and not >return val in your search(otherwise even without checks in the qsearch you could >see Qxf4 Bxf4 Rxh5 null Rh8#). I am glad you raised this as I wanted to talk about. My program is a mixture of return(value), return(beta), and return(alpha) and I've not been happy with that. My quiescence is mostly return(beta). The main search is a mixture. Whenever I make everything return(value), PVS goes weird on me and stops solving problems as well (big drop). What should I do? > >You should check what is the first iteration that Qxf4 Bxf4 Rxh5 null is >searched with remaining depth 1 after null to see if your program detect mate >threat to extend it. > >nor >>Botvinnik-Markoff's extension, but hopefully those will help, though they >>haven't so far. Nor did using checking moves in the quiescence search. >>None of those three has improved the time of the above, for me. I haven't >>tried leaving out all check evasion moves in the main search and quiescence >>search which speeds up the program tons but makes tactical solution rates >>suffer. >> >>New recapture tested just slightly less than 1% worse in score on Win-at-Chess >>for me but is solid enough to be okay to keep as a permanent setting. > >I think that you are wrong. > >The basic rule should be that an extension is probably bad if it does not >improve results in test suites. > >I do not say the same for pruning and I believe that there is a bigger chance >that pruning is good inspite of reducing the result in test suites. > >Test suites usually encourage not even recaptures and it does not mean that it >is good to extend them in games. > >Uri
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