Author: Howard Exner
Date: 21:30:24 08/30/99
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On August 30, 1999 at 19:41:54, Ralf Elvsén wrote: >Some while ago I posted a position where I was >impressed by Hiarcs accurate evaluation in a pawn ending: > >6k1/1p4p1/p7/2Ppp3/1P6/P4KP1/5P1P/8 b - - 0 49 > >The fact that white can create passed pawns on >both sides of the board makes the victory clear, >and Hiarcs gave an evaluation of about +2. Note however >that white is a pawn up. > >Not being entirely convinced about the >impeccabilty of its evaluation, I decided to test >some similar "clean" positions. > >First position: > >4k3/p6p/8/4p3/3p4/3K4/PP4PP/8 b - - 0 1 > >This is (from a human point of view) an "identical" position but >with material equality. A win for white. Here Hiarcs thinks black >is slightly better! > >Second position: > >4k3/p6p/8/3p4/2p5/2K5/P4PPP/8 b - - 0 1 > >Here one pawn is moved from one side of the board to the other >(compared to the previous position) and that makes it a clear draw, >but Hiarcs thinks white has an advantage, although not decisive. >So Hiarcs thinks position 2 is better for white than position 1, >when in fact it is worse. > >I am now inclined to believe (or rather convinced...) >that Hiarcs correct score in the position from my >original post was due to the fact that white was a pawn up in a pawn ending, >(which is heavily weighted, understandably) and not from some accurate >evaluation of the pawn structure... > >Don't investigate the chess "knowledge" of your favourite chess software, >your illusions can be shattered :) > >Ralf > >PS: I always screw things up when I post positions and other stuff. >Hope I got it right this time... 6k1/1p4p1/p7/2Ppp3/1P6/P4KP1/7P/8 b Here is your original position minus the white pawn on f2, so now material is equal. Like Hiarcs' eval of the original Rebel 10 also gives a big plus for white. But now in this equal material position which remains a very simple win for white, Rebel 10 thinks black is much better. It seems that only deep calculation will aid computers here while humans see this at a glance.
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