Computer Chess Club Archives




Subject: Different Hydra personalities against Rybka

Author: Chrilly Donninger

Date: 23:16:50 12/12/05

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.


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