Author: Vincent Diepeveen
Date: 12:05:19 12/26/02
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On December 25, 2002 at 06:21:23, Gerd Isenberg wrote: >On December 24, 2002 at 19:38:27, Vincent Diepeveen wrote: > >>On December 24, 2002 at 03:40:24, Bruce Moreland wrote: >> >>>A backward pawn has the following attributes: >>> >>>1) It cannot be defended by a pawn. >>>2) If it advances, it will be captured by an enemy pawn. >>>3) It is now, or can advance to become, the base of a pawn chain. >>> >>>The classic case is black pawns d6, e5, white pawn e4. >>> >>>The pawn doesn't have to be on an open file. >>> >>>I argue that the pawn cannot be a member of a duo, >> >>I disagree. Some pawns can be member of a duo and backward. >> >>For example white Rb1,c5 >>black b7,c7 Kc8 >> >>b7 is backward. c5 is not. It is isolated. > > >Hi Vincent, > >That's interesting. >I thought backwardness is independent of pieces (per definition) and could >therefore been calculated without considering pieces and stored in the >PawnHash-Table?! This is the major problem of most scientist in computerchess. They see one time in their life a definition of something and then use that till they are old and grey. However evaluation is a big grey area. For a human b7 in the example is backward. Of course a major problem from chess literature versus evaluation in a chessprogram is the classical case where in human chess there are only 2 types of bishops. A good one and a bad one. In my chessprogram there are dozens of bishops though so i ran out very quickly out of names and invented new ones. However bishop evaluation is a peanut compared to pawn structure code. This is a clear example of that. Bruce sees it as the result of tactical pressure that b7 is backwards. That is of course true, but it is a backward pawn from a pawnduo. Whether you advance c7 to c6 or not. b7 keeps backward. When i play away the rook, then b7 is not backwards in DIEP's evaluation but still a little. >What is the exact reason whether c5 is not backward. as i said: c5 is isolated pawn. Not a backward pawn. c5 is a very strong pawn here. Again something to go wrong easily. I can remember so many games of DIEP at the auto232 players of Jan in the past where a strong pawn was by means of tactics very quickly a weak pawn and then the pawn was lost and the game some moves later too. So c5 is a very strong isolated pawn here. I wouldn't possibly know how you could put backwards pawns in a pawntable. Everything is related in chess to the other pieces on the board. In principle nothing is independant evaluated in DIEP. I have the pawntable for terms basically which i didn't improve yet too well. If i would, the terms would consider things i cannot hash. For this reason a year or 2 ago i have thrown out the bishop table in DIEP. There was not a single pattern left that i could hash independantly from bishop+pawns. It won't be too long before i also get rid of my pawntable. Already for passed pawns i cannot hash anything anymore. All i can hash very well is the entire evaluation of a board position, because the nullmove and transpositions cause a lot of times that something evaluated for white, then i can use for black to move. Best regards, Vincent >1. no candidate >2. if two opponent pawns have backward-distance, > the most advanced is not backward. >3. because it's isolated. >Regards, >Gerd
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