Author: Gerrit Reubold
Date: 09:18:41 08/31/99
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On August 31, 1999 at 10:19:35, Robert Hyatt wrote: >On August 31, 1999 at 10:02:19, Gerrit Reubold wrote: > >>Hi all, >> >>Here are two endgame positions which are easy draws (for humans), however, my >>program (Bringer) lost both. Does your programs play better moves? how long do >>they take to see the draw? >> >>Position from Bringer 1.4 - Crafty 16.11, after 155. ... Bb5 >> >>8/8/2k5/1bp5/4p2p/2K1P2P/4B1P1/8 w - - 0 1 >> >>How long does your program take to avoid the losing 156. Bc4?? Instead, >>sacrificing the g2 pawn with Bg4 and keeping the king on c3 should be an easy >>draw. (Bringer would need 6 min on a PII 300 to avoid Bc4 :-( ) >> >> > > >Crafty seens that Bc4 loses in about 30 seconds on my PII/300 notebook, >after getting to depth=18. Score goes from -1.58 to -5.21 at that depth. >The quad xeon sees this in 4 seconds however... Sure, searching faster an deeper helps. I hoped for an answer like "Do this ... and that ..., and your engine will see it immediately". Maybe I have to accept that there are still positions which humans solve easily and progs need some 18 plies. > > > > >>Position from Crafty 16.11 - Bringer 1.4 >> >> - - 0 1 >> >>43. ... g5 would be an easy draw, does any program see this move (BTW, Bringer >>played Kg6 and h5 and lost) >> > > >I'll have to try this one on the xeon, but it is busy. It has all the 3 vs 2 >endings and may be able to search this to the end. >> >>The second position leads to the question: how should we evaluate positions like >>this: >>8/2k5/2n5/8/8/2BN4/2K5/8 w - - 0 1 >>Don't tell me "5 pieces EGTBs", because there may be another black pawn, which >>wouldn't change a thing. >> >> >>Greetings, >>Gerrit > > >Tablebases _will_ help... because often a 20 ply search is more than enough >to find a way to eliminate that last pawn and get an exact score... otherwise >such evaluations are difficult, because _all_ KN vs KBN positions are not >drawn... I was looking for a way to *know* it is a draw, not for searching 20 plies to hit the tablebases. Of course, no one would lose that third position, but knowing its score would help when reaching that position at a leaf node in a 20 ply search. Greetings, Gerrit
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