Author: John Hatcher
Date: 02:27:10 03/19/01
Go up one level in this thread
On March 19, 2001 at 05:23:02, John Hatcher wrote: >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 - - Geez, not my day.... [D]8/4k1p1/6Bp/7P/8/8/2K5/8 w - - 0 1 JOHN
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