Author: Joachim Rang
Date: 11:04:58 12/04/03
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Yes, I think most programs have not the knowledge in which cases one or two pawns are unstoppable in a bishob ending. The tricky thing is, that each pawn is stoppable but not both. It seems that most progrmas don't have any knowledge about that, although I think it si not so hard to implement (but perhaps not worth the trouble if the only criterion is playing strenght). Interesting is, that ChessTiger 15 is quite fast. I think this is due to the fact, that Tiger has some speculative evaluation of passed pawns (theron confirmed that in a posting). This leads sometimes to funny evaluations even if the position is drawn but in that case it obviously helps. regards Joachim 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
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