Author: Gerd Isenberg
Date: 02:49:28 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. Or until you elucidates them. One amazing thing with backward pawns is, that everybody comes up with sample positions, but Bas initial questions still remains open, geay area. My current approach don't consdiders b7 as backward, because of duo, but as a target for a rook on a halfopen file. Anyway, the approach Bas mentioned works even well with your definition, if one considers piece attacks in the domination bitboards. > >However evaluation is a big grey area. Yes for sure. > >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. > OK, but with pawn on c6, b7 is really or better statically backward. >>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. But also isolated pawns may be backward. Isn't it necessary to distinguish between isolated that may push foreward or not? - - - - - - - - - - - - - - - - - - - - - - - - - - - - B - - - B - - - - - - B W - - W - - B - - W - - - - W - - - - - - - - - Here b2, d3 and h4 are backward, but not e5 because it's more advanced than it's counterpart d3. > >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. But i guess it's so strong because of the interaction with b7 and c7/c6. And it crossed already the boarder, a fact where backwardness may become an advantage, specially if there is only one (dynamic) backward guard. The black pawn on c7 disguises the "backwardness" of c5. The weak or dynamic backward pawn on b7 makes c5 not backward. Isn't that the fundamental idea behind minority attacks? Even if the stop square (c6 here) is dominated by black, the remaining pawn structure after bxc becomes a positional monster (isolated double pawn c7/c6). > >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. > Ok, i use several eval passes, the first one rather statically with only a few piece interactions, preparing additional data for further passes, where piece interation is the main issue. Regards, Gerd >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
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.