Author: Miguel A. Ballicora
Date: 14:18:42 12/27/02
Go up one level in this thread
On December 26, 2002 at 15:05:19, Vincent Diepeveen wrote: >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. This might be semantics, but for humans, b7 is not at all the classical backward pawn. On the other hand, throwing a rook in b8 and b7 becomes very strong again. Miguel > >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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