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Subject: Re: Endgame: Best Move and Tuning

Author: h.g.muller

Date: 05:59:37 03/05/06

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It seems that hat you ask for is a better judement in the evaluation on what
end-game positions are won and hich are lost, in such very asymmetric end games
with advanced Pawns. To ask that you could see a mate in 21 in 1 sec is
(currently) asking too much. For a position like this it is essential to
recognize which advanced Pawns are dagerous and which are harmless.

In particular, if the other side has only King and Pawns, while you have pieces
to avoid zugzwang, a single Pawn that finds your King on its path is harmless.
Similarly, a 2-1 sitution with a defended passer, like would occur when black
plays g3-g2, is a harmless stand-off with your King on g1.

You would simply have to make a list of the piece majority required to break
down the opponent's side of such a stand-off. For the 2-1 defended passer 2
Bishops suffice. For a 1-0 undefended passer as would occur after g3xh2, Kxh2, a
single Bishop of the same color would suffice, but without any Pawns of your own
ating power would be considered. (With rook-pawns you would also need to be more
careful in what you need beside it to force a win.)

Tweeking points for passers etc. won't give you a general solution, because the
evaluation really is a very non-additive function. The value of every aspect is
very dependent on what else is on the board. Outside passers, for example, are
unlikely to be worth anything in the presence of Bishops that the other side is
unlikely to lose, while they are a winning advantage in a situation where you
can hope to exchange the Bishops.

So the situation after Bxd3 would be immediately qualified as a win, even in a
3-ply search. It is the move I would play in a human game, (especially a blitz
game), because it imemdiately robs the opponent of all HOPE for a mistake on my
part. The computer equivalent is that it has a much higher priority to convert
to a smaller TB (in a won position of course) than to chose the shortest path to
mate. Conversion in 3 followed by mate in 30 is much better than conversion in
20 followed by mate in 1: if you go for the latter mate in 21, you will really
have to play the 20 moves, since apparently he does not have the appropriate TB.
If you go for the mate in 33, after 3 moves you convert to a TB that he probably
has as well, so he will resign after 3 moves, rather than 20. :-)



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