Author: Dieter Buerssner
Date: 12:11:54 01/26/01
Go up one level in this thread
On January 26, 2001 at 06:06:01, Thomas Lagershausen wrote:
>In the following game played in the cadaques-tournament Fritz played a
>wonderfull pawnsac to get a winning queenending.
>59.b5-b6! is great.
I agree.
>It looks like Fritz have some special endgameknowledge about
>the type of queenendings.I analysed the position 30 minutes with Shredder 5 and
>Yace 0.99 but both are not able to convice me that they could win this
>position.
Hi Thomas. I looked at this with Yace, and you are right, that it will not
move b6. But I think, there is a good reason. I believe Uri's suspision is
totally correct, and Fritz did not look deep enough. After Rxg2 Qxg2
Fritz shows a score of > 5, but later it gets a big fail low, to +1.4 and sees
the loss of a pawn. When it had known this in advance, it probably would have
never choosen b6. I believe the line is much too long, to see a forced win for a
chess program. Probably not many chess programs would give up a pawn here.
The same for Crafty. When I do a few moves in the line, the score drops
immediately from 6.0 to 1.5.
I have some extensions in Yace, that should help to see the threat of perpetual
checks. Perhaps I am wrong, but I believe Yace sees rather fast, that in
the b6 line a pawn is lost. You can also see this from the PV. Only many
moves later, Yace can see, that the Q ending is won for white.
I think, Yace would win this with white after b6, which gets considered,
and fails low later. But this would be more or less pure luck.
After b6 I get
5648651 31.240 -0.51 11t 1...Rxg2+ 2.Qxg2 Qe5+ 3.Qg3 Qb2+ 4.Kh1 Qc1+
5.Kg2 Qd2+ 6.Qf2 Qg5+ 7.Kf1 Qc1+ 8.Qe1 Qf4+
9.Kg2 Qxb8 10.Qc3+ Kh6 11.Qc1+ Kh5 12.Qc7 Qg8
13.Qe5+ Kh4 14.b7 Qa2+ 15.Kf3 {0}
The dangerous pawn on b7 is seen, an the value may be too small (other programs
usually give much higher values to PPs than Yace, however one also has to
consider, that the material value of a pawn is smaller in Yace, than in many
other programs), but it is still one pawn less, than for differnt choices for
the 59th move of white.
Regards,
Dieter
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