Author: Peter McKenzie
Date: 12:24:57 10/07/00
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On October 07, 2000 at 14:49:16, martin fierz wrote: >On October 07, 2000 at 10:41:27, Vincent Diepeveen wrote: > >>On October 07, 2000 at 04:31:09, Peter McKenzie wrote: >> >>>I've been browsing 'Comprehensive Chess Endings, Pawn Endings' by Averbakh & >>>Maiselis, picking out a few interesting looking positions to test my program >>>with. Here is the little test suite I came up with: >>> >>>8/1p4kP/5pP1/3p4/8/4P3/7K/8 w - - bm e4; id "CCE4 479"; >>>8/1pp5/3k3p/PP6/2P2K2/8/8/8 b - - bm Kd7; id "CCE 491a"; >>>2k2K2/8/pp6/2p5/2P5/PP6/8/8 w - - bm a4; id "CCE4 530"; >>>8/pp3p2/8/6kp/8/3K1PP1/PP6/8 b - - bm f5; id "CCE4 608"; >>>8/pp2k1pp/2p5/2P1p3/2P1P2P/6P1/P7/2K5 b - - bm g5; id "CCE4 679"; >>>8/1p6/p1p5/P1Pp2pp/1P1P1p1k/5P1P/6PK/8 w - - bm g3 g4; id "CCE 680"; >>>8/1k6/p4p2/2p2P2/p1P2P2/2P5/P1K5/8 w - - bm Kc1; id "CCE 765"; >> >>all peanuts except #7 kc1 under 1 minute single cpu, > >>i have to checkout Kc1 position 7. i'm at 40 ply now, but it doesn't >>see how to win with Kc1. all moves are +1.96 > >position 7 looks wrong to me. i analysed it a bit - it's one of those >'corresponding squares' studies - the author's intention is this: there >are 3 special squares on the board: a3, e4 and h6. whenever the white >king appears on one of these, the black king MUST be on a5, d6 and g7, >respectively. you call a3 and a5 'corresponding squares' (CS). the point of >all of these studies is this: once you have identified the primary CS, >you can go on and identify secondary CS - for instance f3 corresponds to e7, >because from f3 the white king threatens to move both to e4 and to h5 >very quickly, so black must be ready for this. b2 corresponds to b6, and >so on. to win you must find a square for which the other side has no >corresponding square. >i see the author's intention in this study, but i suppose he forgot something. >the reasoning seems to be that black must do something about his f6-pawn, >but black has a stalemate trick with ...a3,Kb6,Ka5,Ka4 and a5. so white >cannot go after the f6 pawn and the position is a draw. i'm pretty sure >that the main line in peter's book goes >1.Kc1 Kc7 2.Kd1 Kd7 3.Ke1 Kc7 4.Kf2 but here 4 ...a3 is a draw. >(but of course it's rather dangerous to critizice averbakh :-) ) Well spotted, I think you are correct! The study is by Zinar, 1983. > >for a position with corresponding squares which really works and is hard >for computers, check my chess puzzle page, www.fierz.ch/pontresina.htm, >position number 2. the solution is Kb6 or Kc6 followed by Kc7 - fritz >doesnt really see it's winning in this position, just a small +1 or so. > >cheers > martin
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