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Subject: Re: Secrets of Rybka and Fruit from my point of view

Author: Chan Rasjid

Date: 18:33:32 12/15/05

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On December 15, 2005 at 17:44:24, Jaime Benito de Valle Ruiz wrote:

>On December 15, 2005 at 17:05:00, Sergei S. Markoff wrote:
>
>>1) Fruit.
>>
>>Fruit search seems to be primitive. "History pruning" is a variation of
>>well-known idea. After implementing such method in SmarThink some years ago I
>>named it "history-based pruning" and then changed to "ordering-based pruning".
>>The outcome of such methods very depends of whole search model, but anyway
>>history pruning is not the key to Fruit strength.
>>
>>To my mind, the key of Fruit strength is that the "Chess is the art of
>>exchange". So, Fabien's idea about flexible game stages looks to be a beautiful
>>way to improve positional play. Fruit can effectively consolidate the position.
>>It simply knows when to excange to improve position. I think that it's the main
>>key (cumulative with very good tuning of evaluation function). I think Fruit is
>>very perspective. The main line of progress for this project, to my mind, is to
>>add more complicated knowledge and intellectualize a search.
>
>I completely agree with you. People overestimate FruitĀ“s search, and
>underestimate its eval because it looks simple.
>

I cannot comment expertly.

It seems to me there are not many lines in Fruit's eval(). It seems even
I could add more detail terms in its eval_pattern(). So it is confirmed a good
simple evaluation can make a top program.

Thomas of Toga should know something and he empasized on search extention
and the way of Fruit's using nullmove. Does anyone think it wrong?

>
>>2) Rybka
>>
>>Some time ago we discussed with Gian-Carlo Pascutto an idea of create special
>>"SET-tables" with sets of piece-square values indexed by 1) material on the
>>board; 2) king position; 3) pawn structure. Such tables can be calculated by
>>analyzing a lot of games. That time I delayed my work in this area because I
>>found other perspective things.
>>You can see that Rybka executable contains a lot of precalculated tables. And
>>also we all know that Rybka plays positional style. My version is that Rybka
>>uses some variation of SET-approach. At all cases it uses some precalculated
>>positional knowledge, but what sort of it? ;)
>
>Interesting idea.

>Regards,
>
>Jaime

The secret maybe in Rybka's readme file and some comments I read in recent
threads about certain characteristic behaviour it displayed under certain
circumstances and other things.

Vasik, if you are here, am I totally off ?

Rasjid





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