Author: Roy Eassa
Date: 14:32:43 06/04/02
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On June 04, 2002 at 17:18:52, Roy Eassa wrote: >On June 04, 2002 at 16:40:46, Helmut Conrady wrote: > >>>I remember one such position. Where the king had to walk across the board, >>>force the opponent to move a pawn, then back across the board to eat it, then >>>back again. >> >>[D]8/Bk3p1p/1P3p2/KP2n2p/1P1p4/1Pp2p2/B1P5/7B w - - 0 1 >> >>Petrovic 1969 >> > > >Could you (or somebody) explain Black's potential drawing resources here? It >seems to me that White's king can go over to the kingside and win in multiple >ways without ever having to back to the a-file. (I'm sure I'm missing something >for Black -- but what?) > Found this on the 'net: " Mate in 270 moves... FRITZ will play Bb1 to prevent black from playing Pd3, bring its king to a1, Ba2, king to e1, Bb1, and finally move the king to f2 in order to capture the pawn on f3. It does not realize that Pf6-f5 will draw after this capture and the exchange that follows it because of black's queening threats, which prevent all further activities of white. However, despite the long solution sequence, the problem can be solved quite nicely by human beings. A typical path to a solution might proceed as follows: Because of the above drawing chance for black, white's only hope lies in queening one of its pawns on the b-file. To achieve this, white has to conquer square a6. However, he has no moves that put black into zugzwang, because black can answer all white king moves with king moves b7-a8-b7 or b7-c8-b7. However, a typical maneuver in such position is the so-called triangle maneuver, where one king is able to use a 3-cycle to return to its original square, while the other king is only able to make a 2-cycle. White can therefore try to move its king to e1, playing e1-f2-f1-e1, which would gain one move. When the white king returns to a5, we will have exactly the same position, but with black to move. As he cannot move the king because of white's threat Ka6, he has to move pawn. Then the entire sequence is repeated 11 times until black has no more pawn moves and has to answer 254. Ka5 with Kc8 thus allowing Ka6, followed by a mate in 15. "
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