Author: Djordje Vidanovic
Date: 07:57:50 02/12/04
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On February 12, 2004 at 06:03:37, Uri Blass wrote: >The main point is that programs should not evaluate unclear position as winning. > >Black has a big advantage without capturing the pawn so there is no reason to >capture h3 and get unclear pawn endgame. > >evaluating Rxh3 Rh2 as a win for white without search is a msitake but >evaluating it as a win for black is also a mistake that cause Crafty to miss a >simple win by not capturing the pawn. > >Uri I disagree: you could evaluate it as a win for black after capturing the h3 pawn if you have very precise evaluation. Of course, I am talking about Martin Fierz's modification. This just means that Crafty has a faulty eval for this type of sharp and unclear endgame pawn races. To illustrate that it is possible to have a good evaluation take a look at how the new strong program, Patriot (Alpha stage) does: New game 8/7p/8/5p1k/4p3/r6P/P5R1/6K1 b - - 0 1 Analysis by Patriot v2.0: 1...Rxh3 2.Rg7 h6 3.Rf7 Kg4 4.a4 Ra3 5.Rg7+ Kf3 6.Rf7 f4 -+ (-4.93) Depth: 10 00:00:00 448kN, tb=24 1...Rxh3 2.Rg7 h6 3.Rf7 Kg4 4.a4 Ra3 5.Rg7+ Kf3 6.Rf7 f4 -+ (-4.93) Depth: 10 00:00:00 454kN, tb=25 1...Rxh3 2.Rg7 h6 3.Rc7 Kg4 4.Kg2 Rg3+ 5.Kf1 Kf3 6.Rc5 f4 7.Rf5 -+ (-5.04) Depth: 11 00:00:01 740kN, tb=43 1...Rxh3 2.Rg7 h6 3.Rc7 Kg4 4.Kg2 Rg3+ 5.Kf1 Kf3 6.Rc5 f4 7.Rf5 -+ (-5.04) Depth: 11 00:00:01 752kN, tb=45 1...Rxh3 2.Rg7 h6 3.Rf7 Kg4 -+ (-5.20) Depth: 12 00:00:02 1955kN, tb=96 1...Rxh3 2.Rg7 h6 3.Rf7 Kg4 -+ (-5.20) Depth: 12 00:00:02 1964kN, tb=103 1...Rxh3 2.Rg7 h6 3.Ra7 Kg4 4.Kg2 Rg3+ 5.Kf1 f4 6.Ra6 Rc3 7.Ke1 Rc2 8.Re6 -+ (-5.39) Depth: 13 00:00:03 2775kN, tb=153 1...Rxh3 2.Rg7 h6 3.Ra7 Kg4 4.Kg2 Rg3+ 5.Kf1 f4 6.Ra6 Rc3 7.Ke1 Rc2 8.Re6 -+ (-5.39) Depth: 13 00:00:03 2895kN, tb=220 1...Rxh3 2.Rg7 h6 3.Ra7 Kg4 4.Kf2 f4 -+ (-5.52) Depth: 14 00:00:04 3808kN, tb=297 1...Rxh3 2.Rg7 h6 3.Ra7 Kg4 4.Kf2 f4 -+ (-5.52) Depth: 14 00:00:05 4326kN, tb=409 1...Rxh3 2.Rg7 h6 3.Ra7 Kg4 4.Kg2 Rg3+ -+ (-5.66) Depth: 15 00:00:08 6638kN, tb=1415 1...Rxh3 2.Rg7 h6 3.Ra7 Kg4 4.Kg2 Rg3+ -+ (-5.66) Depth: 15 00:00:10 8003kN, tb=2048 (Vidanovich, Faculty of Philosophy 12.02.2004) On the other hand, Ruffian 2.0.0 simply searches very quickly and comes up with 1...Kh4 as its first move, which wins as well. But Ruffian does the search first, while Patriot relies on evals.
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