Author: Vasik Rajlich
Date: 08:03:07 04/04/04
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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
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