Author: Gerd Isenberg
Date: 09:15:17 02/23/04
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On February 23, 2004 at 09:36:46, Uri Blass wrote: >On February 23, 2004 at 09:06:31, Gerd Isenberg wrote: > >>On February 23, 2004 at 07:02:59, martin fierz wrote: >> >>>aloha, >>> >>>i have a question about pins. pins are a rather important feature in chess; some >>>of them are not so bad, some are deadly. i just happened to chat briefly with >>>anthony cozzie on ICC, and he said he didn't do any pin detection. i detect >>>pins, but i don't evaluate whether a pin is not so bad or deadly. my questions >>>are: >>>-> are you detecting pins in your program? >>>-> if yes, do you try to distinguish between different pins? >>> >>>cheers >>> martin >> >>Hi Martin, >> >>yes i detect pins, (not only) because i do legal move generation. >>With disjoint direction attacks (from sliders as well from the king as >>metasliders) it is rather cheap to get them without branches. >> >>In Eval i consider (from memory): >> >>1.) what kind of piece/pawn is pinned. >>2.) whether the pinner (?) is en prise or attacked by equal valued pieces. >>3.) The distance from pinned piece to the king (>2) and whether the pinned piece >>is member of the "own" side of the board... >>4.) whether the pinned piece is defended or defendable (in one move) by pawns. >>5.) whether the piece is attackable by opposite pawns. >>6.) a kind of SEE value considering all other attackers/defendes. >> >>In Eval i even consider other "tactical" stuff, like forks, overloading pieces >>and pins to other valueable or hanging pieces. >> >>Cheers, >>Gerd > >I wonder what is the reason that with all of this very impressive stuff you >consider Yace and Sos as stronger than your program based on another post. I don't know what Yace and Sos do in their eval - they were a bit unlucky at IPCCC04. I found nothing impressive with considering pinned pieces and other tactical stuff in eval. > >What is your opinion the relative advantages of program like Crafty relative to >your program and I am not talking about parallel search because yace is not >stronger than Crafty on one processor based on the results that I read. > No idea. I don't do any autoplayer games. >I wonder if you really test every change that you do in the evaluation to test >if it is productive. > >I test every single change that I accept in the evaluation first in positions >and later in blitz games(except cases that the change is relevant only to a very >small class of positions) and if I do not get positive result in blitz games I >reject the change. > But may be a few combined changes leave a positive result, if each single change does not. >It is one of the reasons that I have relatively simple evaluation. >The second reason is that I do not work enough on my program. > >Uri Probably the more success oriented approach ;-) My time is very limited too due to a 40++hours job, so i satisfy my bitboard obsession... Gerd
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