Author: Robert Hyatt
Date: 08:34:59 03/26/03
Go up one level in this thread
On March 26, 2003 at 11:11:30, Peter Berger wrote: >On March 26, 2003 at 11:02:06, Robert Hyatt wrote: > >>On March 26, 2003 at 06:28:52, Peter Berger wrote: >> >>>These can be tough or very easy depending on engine - some engines seem to know >>>too much here. They are also interesting for humans I think. >>> >>>6k1/p4p2/6p1/1P2p2p/4q2P/4Q1P1/P4P2/6K1 b - - 0 1 >>> >>>1..Qxe3! wins for black. >> >>I don't think these are about "knowledge". They are about "search" since the >>first position >>has blacking giving white an outside passed pawn with the two to one majority on >>the >>queenside. > >Maybe. Crafty is one of the engines that has quite a hard time with this >position as is Ruffian (that has even more problems). So I think it is about >knowledge, or maybe about tuning?! I don't think so, for the reason that white has what appears to be a won ending if queens are removed, because of the 2-1 distant majority. Crafty understands this perfectly well. And it takes it a while to see that the king is in just the right position so that black's eventual threats can't be met properly. Both have the same basic motif, a 2-1 queenside majority. The second is simply not a problem for Crafty because of its knowledge about the potential distant passed pawn. The first is more of a problem in that it requires a deep search to discover that the distant passed pawn knowledge really doesn't apply. > >Which one is the rule, which one the exception? Position 1 or 2? For non-master >humans after the queen trade both positions look won for white at first sight I >think. > That's the point. And Crafty instantly agrees as a distant passed pawn produces a pretty large swing in the score. The first position is a definite exception, althought there are plenty of them in general. But given the choice, I'd _always_ prefer to have that 2-1majority myself, knowing that there are some small number of exceptions to the general rule notwithstanding. >Crafty was playing the white pieces in this game and lost, I don't have the PGN >though. Was it "crafty" on ICC? If so I have every game it has played and can find the PGN file for the game. however, I'd be more worried about a program that plays Qe3 on positional grounds because I believe that will be wrong _far_ more often than it is right, this position being a good example of the latter type of exception.
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