Author: Ralf Elvsén
Date: 03:16:22 08/31/99
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On August 31, 1999 at 04:51:18, Ricardo Gibert wrote: >On August 31, 1999 at 00:30:24, Howard Exner wrote: > >>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. > >Yes. Computers cannot calculate far enough to "understand" these positions. >Their evals are not much better than "random noise". They can do tactics & in >many respects positional play, but stategy (i.e. planning) is neglected, which >is what is needed here. To do stategy, they need to be able to generalize and >they don't do that. I don't know if strategy is needed. As a naive non-programmer I imagine that you could add something like this in the evaluation: local pawn majority (plus check for non-block e.g. white pawns g2, h4, black pawn h5) -> future passed pawn if (the above) on both sides of the board -> big plus in score Of course it depends on the position of the kings etc. Might get messy... I think Bob indicated a scheme similar to this in a previous post (or maybe I misunderstood him). Note that in the last positions I posted, if you let black have pawns on e.g. e4 and d4 and alter the location of the kings slightly, then black can win in some situations... Ralf
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