Author: John Hatcher
Date: 02:23:02 03/19/01
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On March 19, 2001 at 05:21:08, John Hatcher wrote: >On March 19, 2001 at 04:27:48, Steffen Jakob wrote: > >>Hi, >> >>in a game between Hossa and Crafty the following position occured: >> >>[D]8/8/8/8/p7/Pb6/1P6/K2k4 w - - >> >>White gets mated in 6 moves: >> >>1.Kb1 Bc2+ 2.Ka1 Kc1 3.Ka2 Bb3+ >>4.Ka1 Bc4 5.b4 a4xb3 6.a4 b2# >> >>Hossa sees this very fast of course, but when I looked at his analysis I saw >>that he evaluated the first few plies as a draw. The reason for this is that >>e.g. the position above matches an eval term where Hossa "sees" that black has a >>wrong bishop (the extra white pawns are included in that term). And in fact >>white's position seems to be very unlucky here. E.g. I think if white's king is >>somewhere else than on a1 or b1 then it is a draw. Also if the b2 pawn wouldnt >>be there or somewhere else it looks like a draw. I think that even if in the >>same position the pawn a3 wouldnt be on the board it is a draw (?). >> >>So it seems as if this is a very rare exception to my rule that the maximum >>score for the side with the bishop is a draw if one side has "a" or "h" pawns >>and a wrong bishop and the other side has 1 or two pawns. >> >>Do other engines who have some knowledge in such positions have the same problem >>in the static evaluation of that position? >> >>Can you think of extra conditions to handle this problem? >> >>Can you think of other positions where >>- one side has only a or h pawns >>- has the wrong bishop >>- the weaker side has 2 pawns >>- no pawn of the weak side is attacked by a pawn of the side with the bishop >>- the a/h passers dont run in a trivial way >>- it is a win for the bishop side??? >> >>Best wishes, >>Steffen. > >This position arose, with colors reversed, in an old endgame study (Walker >1841), which can be found in Rueben Fine's "Basic Chess Endings" as diagram No. >153. The starting position of the study is: > >[D]wKc3,Bg6,Ph5/bKe7,Pg7,h6 > >By the way, Fritz finds the mate instantly. > >Regards, >John Sorry, here's the diagram: [D]wKc3,Bg6,Ph5/bKe7,Pg7,h6 w - -
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