Author: John Timm
Date: 10:54:38 09/26/98
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
By "easily" the GM probably
meant something like: "Black definitely wins if he plays correctly, and it is
easy to do so because Black is under no pressure and can slowly and inevitably
improve his position by making natural moves, whereas White faces difficult
defensive choices on almost every move" (GMs always think they can play such
positions correctly, and are surprised and disappointed if they don't).
If Fritz plays B:f3 in this
position, it just means that Fritz plays this position very badly. I doubt that
any human master would think that B:f3 is a good move. Black gives up Bishop for
Knight, AND gives up the Bishop pair (both in a position that is very favorable
for Bishops) AND cashes in one of his advantages too early (Black can always
arrange a trade of Bishop for Knight later, whereas White can't do the same -
therefore Black limits his options but not White's by a premature trade).
Instead, the
correct plan is for Black to gradually improve his position by moves such as f6,
Kf7, e5, Ke6, Bb4 and to gradually break through on one side or the other -
White has no active plan to improve his position and must wait passively.
Whether the win is "easy" for any player obviously depends on that player's
level of technique, but if you doubt that Black wins with accurate play see the
wins for B v. N in Fine's Basic Chess Endings, ## 241-246 (with BB v. NN the win
is even "easier" than in ## 241-246).
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