Author: Robert Hyatt
Date: 08:07:01 09/25/98
Go up one level in this thread
On September 25, 1998 at 02:49:28, blass uri wrote: > >On September 24, 1998 at 11:43:38, Robert Hyatt wrote: > >>In the ICCA Journal, Vol. 16, No. 4, GM Timoshchenko is comparing various >>chess programs on how they evaluate bishops vs knights. He gives several >>positions, with this one being the most interesting at present: >> >> >> +---+---+---+---+---+---+---+---+ >> 8 | | | | | | | *K| | >> +---+---+---+---+---+---+---+---+ >> 7 | *P| *B| | | *B| *P| *P| | >> +---+---+---+---+---+---+---+---+ >> 6 | | | | | *P| | | *P| >> +---+---+---+---+---+---+---+---+ >> 5 | | | | | | | | | >> +---+---+---+---+---+---+---+---+ >> 4 | | | | | | | | | >> +---+---+---+---+---+---+---+---+ >> 3 | | | N | | P | N | | P | >> +---+---+---+---+---+---+---+---+ >> 2 | P | | | | | P | P | | >> +---+---+---+---+---+---+---+---+ >> 1 | | | | | | | K | | >> +---+---+---+---+---+---+---+---+ >> a b c d e f g h >> >> >>fen: 6k/pb2bpp1/4p2p///2N1PN1P/P4PP/6K/ w - - >> >>Here is the gist... to feed this to a program and with no searching, >>see how it evaluates this. Chessmaster 2100 says -.26, Fritz-2 says -.47, >>and chess-genius 1.0 says -.48. I recently fixed two "holes" in Crafty's >>evaluation, one concerning "if you have one bishop in the ending, get your >>pawns on the *other* color squares" and the other "if in an endgame, with >>pawns on both wings, a bishop is significantly better than a knight." >> >>This last influences the evaluation of the above position quite markedly, >>because this is an endgame, and black is going to get the bishop-over- >>knight in endgame bonus two times since black has two bishops, white has >>none. Black also gets the traditional bishop-pair bonus as well, which >>might or might not be overkill here. In any case, I first gave this to a >>GM to look at and the response "black wins easily." Not surprising, the >>bishop pair vs the pair of knights should favor the bishops. > > > > I do not agree that black wins easily. >If black is fritz5 than black plays Bxf3 and has not pair of bishops. > >I do not think that pair of bishops wins easily >In the game Boris Avruch against Junior4.9 the grandmaster had an advantage of >pair of bishop and a pawn against bishop and knight and could not win(there were >pawns in both sides of the board 4 against 3 in 1 side and 2 against 2 in the >second side). >I believe that if you asked the GM about the position he would say that the 2 >bishops with a pawn wins easily bishop and knight > >Uri First, *I* wouldn't play Bxf3. It doesn't gain anything for black and tosses the bishop pair. Notice that this position is *two bishops* vs *two knights* and not BB vs BN as you describe above. That is why the GM said "black wins easily". He didn't say this about *any* of the other positions (BB vs BN, and the others with B vs N with either a rook or queen helping). It doesn't matter to me what "fritz" would play. If it plays Bxf3 it is playing the only reasonable move to draw. But *two* GM players believe that this is won by black for the case BB vs NN, which is the main case I was discussing...
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