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Subject: Re: Wildcat could not win an easy ending versus CM for PS2

Author: Tord Romstad

Date: 06:54:24 01/19/04

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On January 18, 2004 at 20:14:32, Jorge Pichard wrote:

>After several moves with no advantage for white CM PS2 offered a draw and I
>adjudicated the draw, since it was clear that WildCat did not had a clue of how
>to convert a win out of this easy position. All that WildCat had to do was
>advance the b pawn forcing CM PS2 to resign eventually.

I haven't studied the game, but I think the probability that you adjudicated
too early is rather high.  It is quite common that chess programs finally
manage to win such endings, even if they have no clue how to play.  It just
takes very many moves.

What typically happens is this:  The program with the winning position
realizes that it has a clear advantage, but doesn't see a forced win.  In
such situations, it will shuffle the pieces around without a plan, but
carefully avoiding repetitions.  Finally the engine will be forced to
push a pawn in order to avoid the 50 move rule.  Quite frequently, this
pawn push, which the engine avoided as long as it could without allowing
a 50 move draw, is precisely the winning line.  I think it is quite likely
that this is what would have happened if you had continued playing.

Early versions of my engine had no endgame knowledge at all, and evaluated
all endgames as middlegame positions.  When it ended up on the winning
side of a KQK endgame, it therefore tried to keep the opponent's king
on the middle of the board, which is of course precisely the opposite
of the winning plan for this endgame.  Despite this, it always managed
to win this endgame, albeit in a very inefficient way.  After many moves,
it had to force the enemy king away from the centre in order to avoid
a repetition draw.  Finally, usually just before the 50-move rule would
be invoced, the enemy king would be close enough to the edge that my
engine could see the mate.

Tord



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