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Subject: Re: how does crafty understand that black is better?

Author: Ricardo Gibert

Date: 10:33:22 04/08/03

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On April 08, 2003 at 10:04:02, Uri Blass wrote:

>[D]8/5pp1/4p1kp/1Q6/2rqP2P/8/5PP1/5RK1 w - - 0 27
>
>This position happened in a game of movei.
>For the game see http://f11.parsimony.net/forum16635/messages/46511.htm
>
>I found that latest movei also suffers from the same evaluation problem.
>
>Movei evaluates the position as almost equal.
>
>I found that Crafty and a lot of programs understand that black has a clear
>advantage(more than 0.5 pawns for black from the
>first iterations).
>
>I understand that black is better but the question is what factor in evaluation
>helps a lot of programs to understand it.
>
>I can explain reasons to give advantage for black from program point of view:
>
>1)The black king is more advanced and it is known that the king should
>be at the last rank except endgames.
>
>2)The white pawns are more advanced so by piece square table they
>get bigger bonus after a move like h5+.
>
>Uri

Comps will score the position as better for Black, because:
(1) Black is more centralized
(2) Black's Rook occupies an open file.
(3) White's Rook passive.

Plus a short amount of analysis will reveal that White's pawns on the 4th rank
are in hot water. White's f-pawn is pinned and Black's Rook can readily occupy
White's 2nd rank and increase the pressure.

In the root position, Black should not be recieving a bonus for a "more active"
King in the endgame, because in such major piece endings, King safety is still
important.

All that said, a human would play 1.Qb1 expecting a computer to continue
1...Qxe4 2.Rxe4 g3 with a technical draw. Though Black often has good practical
chances in such endings, in this case, White's pawn structure is ideal with his
h-pawn perfectly placed on h4.

It's possible that there exists a program that understands such positions (with
the addition of a lot of Rook endgame knowledge). I'd be curious to find out
which ones can do this. Such a program would perhaps prefer something like
1...Rb4 2.Qe1, etc.



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