Author: Aivaras Juzvikas
Date: 08:13:18 04/04/04
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On April 04, 2004 at 11:09:05, Vasik Rajlich wrote: >On April 04, 2004 at 11:03:07, Vasik Rajlich wrote: > >>On April 04, 2004 at 10:55:38, Aivaras Juzvikas wrote: >> >>>On April 04, 2004 at 10:48:55, Vasik Rajlich wrote: >>> >>>>On April 03, 2004 at 06:29:13, Aivaras Juzvikas wrote: >>>> >>>>>On April 03, 2004 at 06:21:51, Vasik Rajlich wrote: >>>>> >>>>>>On April 03, 2004 at 04:02:57, Aivaras Juzvikas wrote: >>>>>> >>>>>>>i have got this problem here, check extention explodes in the endgame pawns + >>>>>>>rook or queen, all these open files make it possible to check endlessly. how to >>>>>>>restrict this? i added smth like this: if ply > depthtoreach + 4 then dont >>>>>>>extend, where depthtoreach is the depth im searching to. but this is ofcourse >>>>>>>not very good, because i still get those check extentions where its impossible >>>>>>>to mate anyway. how did u solve this problem? an idea would be to store info >>>>>>>into transposition table when not to extend, but how to find that out? >>>>>> >>>>>>Are you extending checks, check evasions, or both? >>>>>> >>>>>>The third option is quite appealing, but there are some issues. :-) >>>>>> >>>>>>Cheers, >>>>>>Vas >>>>> >>>>>when side to move in in check i extend, so i guess it would be a check evasion >>>> >>>>So, in certain positions, you are extending every other move. It's true that in >>>>these positions this will severely hurt your nominal depth, but if you test with >>>>the extension and without it you should see a clear benefit. I don't remember >>>>any claims to the contrary. >>>> >>>>Vas >>> >>>well here is a claim to the contrary: in endgame rook+pawns vs rook+pawns >>>instead of dealing with passed pawns the engine keeps on extending checks >>>endlessly thus overall looking very few ply ahead and the result is a loss of a >>>rook due to pawn promotion. usually (w/o endless check extention stuff) i reach >>>15-17 ply depth in endgame, with check ext. stuff i get 7-8ply, and again only >>>when slider like rook or queen is present which can keep on checking no matter >>>what you do. dont u restrict your extentions somehow? please share with me how >>>to do this >> >>Aha. That's a good point, maybe it's worth testing. >> >>My program Rybka always extends every check one full ply. >> >>However, maybe it should be a bit less in the endgame, and perhaps even a bit >>more in the middlegame. (This I did experiment with.) >> >>This is worth some tests. >> >>It would be interesting if you posted some numbers. (You can always find some >>good cases, and some bad cases.) >> >>Vas > >One more thought about this: in the endgame, it may be a question of calibrating >against pawn push extensions. (Ie rather than decrease the check extension, >increase the pawn push extension.) > >A few months ago I played around with some hyper-aggressive passed pawn >extensions, up to 3 plies extra for any pawn which reaches the seventh rank in >an endgame. > >It worked nicely on some tactical problems, but there were also some exploding >searches. > >Cheers, >Vas my engine is brand new and instead of many features it has many bugs -> the only extention i have now is this check (evasion i guess) extention. so meybe instead of restricting this extention i should add pawn on 7th rank extention and see how it does. what else is there in endgames to deal with besides mates and promotions?is there any other must-have extention i am missing?
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