Author: Ricardo Gibert
Date: 13:18:10 08/29/99
Go up one level in this thread
On August 29, 1999 at 14:20:16, Mark Young wrote: >On August 29, 1999 at 13:30:20, Robert Hyatt wrote: > >>On August 29, 1999 at 12:36:18, Ralf Elvsén wrote: >> >>>This is a position from a game Hiarcs 7.32 - Crafty 16.6 >>>Time 25 min/game, ChessBase interface etc, but that is not >>>important. >>> >>>6k1/1p4p1/p7/2Ppp3/1P6/P4KP1/5P1P/8 b - - 0 49 >>> >>>What is interesting is that Crafty (black) >>>thinks the position is about even, with a score fluctuating >>>around equality, while Hiarcs for several plies >>>has realized that it has a won position and >>>has a score about +2 (an exchange of rooks has just >>>taken place some plies ago). >>> >>>I checked 16.6 as a winboard engine, also 16.16: >>>same result. >>> >>>This is a serious mis-evaluation of >>>the pawn structure since white easily can produce >>>passed pawns on both sides of the board, while >>>blacks connected free pawns can do nothing. >>> >>>Bob, maybe you want to look into this... >>> >>> >>>Regards, Ralf >> >> >>This is a bit speculative by hiarcs... ie I have seen it do this same sort >>of evaluation and be dead wrong as well... >> >>the only thing I don't evaluate at present is pawn majorities which turn into >>distant passed pawns. It is on my todo list, and I have some code written that >>does pretty well but is not ready for testing on the servers yet... >> >>My version of crafty (16.17 as released) thinks black is worse here, by about >>1/3 of a pawn... and as it advances pawns to make passed pawns, this gets >>worse. But there is always danger in these positions... and I only hope that >>I get more right than wrong... however, +2 here? Seems hard to fathom... > >I don't know if this is a case of specuation by Hiarcs or something else. I did >test some other programs on this position and they tend to agree with Hiarcs >7.32. > >5 min search. > >Crafty 16.13 Fritz 5 Junior 5 Hiarcs 6 Hiarcs 7.32 > > +/= .43 +- 1.56 +- 2.07 +- 2.16 +- 2.23 Hard to fathom? This position is a good example of a type of position that strong players find easy while computers suck at in comparison. In a matter of seconds, a strong player would use schematic thinking to solve it by dividing the position into 3 sections: Section 1 are the a, b & c files, where the 3 vs 2 pawn majority will prevail unless the black K assists. Section 2 are the d, e & f files where the white K & f pawn will hold off the black pawns even with the assistance of the black K. Section 3 are the g & h files where the 2 vs 1 pawn majority will prevail unless the black K assists. Unfortunately, The black K can only assist in a single section so white Queens. The 2.23 pawn advantage given by H7.32 is ludicrously low! For example, even if we alter the position drastically in blacks favor, he still loses uneventfully. We can move the white K back to d1 and put the black K on d3 and white still wins easily.
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