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Subject: Re: Different Hydra personalities against Rybka

Author: Ryan B.

Date: 13:40:27 12/13/05

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On December 13, 2005 at 15:51:41, Vincent Diepeveen wrote:

>On December 13, 2005 at 14:35:27, Ryan B. wrote:
>
>>On December 13, 2005 at 08:35:07, Chrilly Donninger wrote:
>>
>>>On December 13, 2005 at 06:08:49, Ryan B. wrote:
>>>
>>>
>>>>
>>>>Does the standard version of Hydra use any foward purning other than Null move?
>>>>
>>>>Ryan
>>>Everybody uses nowadays additional pruning. Otherwise the big search-depths
>>>would not be possible. Hydra uses them too. But so far not History-Pruning. Did
>>>not work with the other pruning techniques.
>>>The kind of pruning is a secret. One big error - publishing NullMove - is
>>>enough. But NullMove was anyway known in the community.
>>>
>>>Chrilly
>>
>>I suspected that most strong programs use additional pruning.  I asked because I
>>read a claim by Vincent that Deip and Zappa only use Nullmove for pruning.
>>
>>Ryan
>
>Diep world champs 2005 version used history pruning. Normally it runs without
>pruning. dutch champs it used no pruning other than nullmove.
>
>Zappa uses only nullmove. The world champs version of zappa was just nullmove.
>I'm not sure whether he's gonna use pruning in future, you'll have to ask
>himself.
>
>Diep is not going to use history pruning *ever again*. Last plies pruning or
>something else i might retry however.
>
>Did do a lot of tries there. Point is, when i play a 100 games or so and the
>statistics indicate it scores me less points, then i kick out something.
>
>That happened to history pruning too. The tournaments we play, we play at quads
>or something big, that means that testing a 100 games is not easy, as
>in my case i simulate it with 180 0 games at a dual k7, each program its own
>dual k7.
>
>Vincent


Interesting, in my experience other than null move most pruning methods are only
good at blitz time control or on slow hardware so I am not surprised that Diep
only uses null move as I doubt you are interested in blitz results.  One that I
think is only a small improvement but helps at all time controls for me is
extended razoring with researches when value is over alpha.  A more complicated
algorithm for doing researches may help but I have not found it yet.

Ryan



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