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Subject: Re: Spike-Rybka

Author: Vasik Rajlich

Date: 02:43:19 12/29/05

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On December 28, 2005 at 15:18:59, Albert Silver wrote:

>On December 28, 2005 at 12:44:45, Vasik Rajlich wrote:
>>On December 28, 2005 at 08:37:42, Albert Silver wrote:
>>>On December 28, 2005 at 03:12:23, Vasik Rajlich wrote:
>>>>Interesting game. I didn't like .. h6 and .. g5 by Rybka in the opening (as I
>>>>suspect most human players won't), and there were a few moments in the endgame
>>>>where better resistance could have been put up - but these are relatively minor
>>>>The biggest issue was the incorrect sacrifice of the h6 pawn. The Rybka static
>>>>eval incorrectly gives the following position (and others of a similar type) as
>>>>roughly equal:
>>>>[D] 8/1b2b1k1/pp1ppp2/nPq5/P1P1P3/2QRNPP1/8/1N2KB1r b - - 0 27
>>>>I'll keep to myself my proposed solution. It's a tricky issue and won't be
>>>>handled until after the Rybka 1.2 release. If anybody wants to share here, I am
>>>>all ears :-)
>>>Is the error related to the rook on the 8th?
>>Actually I should take a closer look. This rook gets a very nice bonus compared
>>to the one d3, not sure itīs deserved.
>I asked because I've noticed how aggressively Rybka evaluates rook penetrations,
>usually correctly so, but here the rook is biting on dust. It isn't threatening
>or preventing anything, and can easily be evicted by the king+bishop
>combination. I just wonder whether this was what caused the pawn sac in the
>first place.
>                                           Albert

Yup. Of course you have to be careful when sacrificing, as this game shows. One
nice thing about having an extra pawn is there is almost always a long-term
plan, only some blockade positions are an exception. Dynamic play can peter out


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