Author: Uri Blass
Date: 06:36:46 02/23/04
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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. 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. 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. 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
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