Author: Sylvain Renard
Date: 02:24:39 03/30/99
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>>I found a position when Junior (using tablebases) goes wrong in the winning side >>of KRP vs KR >>6R1/7k/5P2/8/8/8/7r/K7 w - - 0 1 >>Fritz's tablebases show the right winning move 1.f7 (8) (I do not understand >>8) but after this move the tablebases show for black Rf2 with draw. Yes, good work! But this is kind of error is easy to understand because on Fritz CD ROM there are the Ken Thompson's files : Pr_r.g, Rb_r.g, Rn_r.g but the file Rr_r.g is missing. After 1...Rf2, the only winning move is 2.f8R!! all other moves lead to a draw. >At that point white has a "Won" endgame and abandons the CD ROM because it >believes the program can win the game from there. No it is because it does not have the good file on the CD! The file Rr_r.g is missing. >Yes, this is an error in the tablebase. Because it is uncomplete. >>I am not sure about the result of 2.f8Q, the only question is if black has a >>perpetual check and I did not analyze this position and did not check it with >>KQR vs KR tablebases. If you have Ken Thompson CD N°1 (and for instance ChessBase) you can check it's a draw. >Yes, I believe the 2. f8=Q is a draw because of moves like Ra2+. >Jim Walker It is confirmed both by Ken Thompson database (when complete...) and Edward's tablebases (and human thinking too!). My program Capture uses Edward's tablebases. It plays 1.f7 and announces mate in 20 moves. I have also checked that after 1.f7 Rf2 2.f8Q?? it plays 2...Ra2+ and announces a draw. Best regards, Sylvain Renard
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