Author: Uri Blass
Date: 08:03:43 12/04/03
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On December 04, 2003 at 10:55:06, Jaime Benito de Valle Ruiz wrote: >(ALL these tests are done with 3,4 and some 5 tablebases in an Athlon 1900+ with >512 Mb) > >This position was recently posted by Joachin Rang, and no one really suggested >why is it so hard for commercial engines: > >[D]8/5R2/2p5/8/7P/1K2b3/P3kp2/8 w - - 0 1 > >My guess is that some engines' evaluation are not "aware" of the danger of two >passed pawns being stopped just by a bishop, and because of pruning and/or >Null-move, they need to reach a great depth to find the move. > >For example, in this position (4 plies after the initial one)... > >[d]8/8/2p5/8/7P/4b3/P1K5/5k2 w - - 0 3 > >Shredder 7 needs a depth of 17 to give it a positive score (over +4.00), and >realize it's winning. >Fritz 8 needs only 14 to come up with a positive score(+0.44), but it takes >longer than for Shredder. Later, at depth 17 the score is a convincing +5.75. >Junior 8 needs to reach depth 21 (fast, though). > >[D]8/6p1/P1b1pp2/2p1p3/1k4P1/3PP3/1PK5/5B2 w - - > >In this other position, the problem appears to be the same: After several plies >we have: > >[d]8/P5p1/8/2p1p3/1k1P4/4p3/1PK3b1/8 w - - 0 6 > >Both Fritz and Shredder need depth 12 from here to give a positive score! Any >(bad) player would realize almost instantly that white are winning here! > >Does it make sense what I'm saying? > >Regards, > > Jaime Of course programs are basically stupid in detecting unstopable passed pawns. The practical importance of this problem was simply not big enough for the commercial programmers to care about fixing the problem until today. Uri
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