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Subject: Re: Different Hydra personalities against Rybka

Author: Kolss

Date: 03:33:05 12/13/05

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On December 13, 2005 at 03:16:20, Vasik Rajlich wrote:

>On December 13, 2005 at 02:16:50, Chrilly Donninger wrote:
>
>>I experimented recently with a Shredder-style search in Hydra. The
>>single-processor Shredder/Hydra completly demolished Shredder. If two programs
>>are similar, the strength difference is enlarged. Its therefore a bad idea to
>>tune a programme against itself.
>>But the Shredder/Hydra made only 40% against Rybka. Changing back to the
>>standard Hydra-search its between 75-80%. Rybka is regularily "killed" in
>>king-attacks. As noted before, this numbers are for Hydra-single-processor. The
>>PC-programm is running on a 3.2 MHz Pentium 4. Time control is 30secs/move. A
>>standard-opening set similar to the Nunn-openings is used.
>>
>>Changing the search is not only a tactical matter. The playing style is to a
>>large extend also influenced by the search. If two moves are from the evaluation
>>point similar, the programm usually plays the one with the larger search tree.
>>Or in other words: The lines which are extended. The Shredder/Hydra played
>>over-aggressive, whereas the classical Hydra with the right dose.
>>
>>One conclusion of my experiment is: Rybka seems to be fairly tuned against
>>Shredder. This is always the fate of the leader of the gang. In the future other
>>programs will be tuned against Rybka and it will be much more difficult to stay
>>on the top.
>>
>>The experiment shows also, that it is fairly easy to tune against one programm.
>>The problem is to find a solution which works against all.
>>
>>Chrilly
>
>Hi Chrilly,
>
>what you write is very interesting. I can add three things:
>

Hi Vas,

>1) 99% of Rybka testing was against Shredder 9. It was more of a practical
>thing, each previous version had a "rating" against Shredder. In the future we
>will be more complete of course.

That is very interesting (:-) and makes it all the more astonishing that you
have managed to produce such a strong program!

>2) I have also seen the phenomenon where differences are exaggerated against an
>older version. In particular, I have found that adding just one smaller but
>sound eval term often gives fairly nice scores against the old version while
>games against a completely different engine will sink into statistical noise.

The same with Ikarus. I quite regularly produce versions which outscore the
standard version by 30 or even 60 ELO points in direct matches by just doing
some tweaking or adding or removing a term here or there. But in *most* cases,
these versions do worse (often by about 50 ELO points!) against a standard set
of different opponents.

Self-play can give you a hint that you screwed something up completely, but it
is no serious way to measure progress / improvement.

Best regards - Munjong.



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