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Subject: Re: Misevaluation in endgame by Gambit Tiger 1.0

Author: Robert Hyatt

Date: 14:34:24 02/12/01

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On February 12, 2001 at 03:39:05, Sune Larsson wrote:

>On February 11, 2001 at 22:13:00, Robert Hyatt wrote:
>
>>On February 11, 2001 at 18:23:01, Uri Blass wrote:
>>
>>>On February 11, 2001 at 18:10:33, Robert Hyatt wrote:
>>>
>>>>On February 11, 2001 at 12:24:21, Vincent Lejeune wrote:
>>>>
>>>>>in this position :
>>>>>
>>>>>[d]k7/p7/1p6/3p4/3K1B2/r7/8/4R3 w - - 0 1
>>>>>
>>>>>Gambit Tiger 1.0 gives +2.14 for white , I think it's a big overevaluation for
>>>>>white !
>>>>>
>>>>>
>>>>
>>>>
>>>>It's a common enough error.  In reality if anybody wins, black wins. White
>>>>has no winning chances at all.
>>>
>>>
>>>I disagree.
>>>
>>>In a game between humans white has chances because he has chances to capture all
>>>the black pawns and win the KRB vs KR endgame.
>>>
>>>In a game between computers white has also chances if the defender does not use
>>>the KRB vs KR tablebases.
>>>
>>>It is a draw but I prefer white because white captures one pawn and is not going
>>>to lose with Rook and bishop against Rook and 2 pawns beacause the pawns are at
>>>a7 and b6 and the king is in the middle of the board so it is easy for white to
>>>prevent the pawns to get forward.
>>>
>>>Black practically may lose by the following steps:
>>>1)losing the pawns
>>>2)not finding the right moves in KR vs KRB endgame.
>>>
>>>Uri
>>
>>
>>Black can also drop dead and his flag will fall.  :)
>>
>>Otherwise I can't imagine black losing this.  Drawing KRB vs KR is _not_
>>a difficult task.
>
> For humans it's a tricky ending. I've seen several players, rated above ELO
> 2400, lose this KR vs KRB. And that under serious tournament conditions.
> Guess you have to know it thoroughly. I, for sure, don't.
>
> Sune

By the same token, I have seen GM players unable to win KQ vs KR, yet it is
actually not hard at all once you know the ending.  Had a player (USCF master
yet) explain it on rec.games.chess.computer a couple of years ago and I had no
problem following his 'plans'.

But for a computer to enter a KRPPP vs KRB and think the rook and bishop is
going to win is not a good idea.  Crafty occasionally draws such endings too
easily as it will trade a piece for the opponent's last pawn knowing that
it then can't lose, period.  It wins many such positions, but it might have been
an easier win keeping the piece.




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