Computer Chess Club Archives




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

Author: Stuart Cracraft

Date: 10:45:10 12/16/05

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On December 16, 2005 at 06:47:50, Uri Blass wrote:

>On December 16, 2005 at 01:49:44, Stuart Cracraft wrote:
>>On December 15, 2005 at 21:14:17, Ryan B. wrote:
>>>On December 15, 2005 at 19:57:45, Uri Blass wrote:
>>>>On December 15, 2005 at 19:38:51, Stuart Cracraft wrote:
>>>>>On December 15, 2005 at 19:18:37, Uri Blass wrote:
>>>>>>I also agree and I never underestimated fruit's evaluation.
>>>>>>It is possible that the main reason for it's superior evaluation is the idea of
>>>>>>average between opening and endgame but it is fact that it has a superior
>>>>>Really? Just the line from fruit:eval.c:
>>>>>  eval = ((opening * (256 - phase)) + (endgame * phase)) / 256;
>>>>>I find that VERY hard to believe. That concept has been around a
>>>>>very long-time.
>>>>I do not read much source code of free programs so I do not know but I wonder
>>>>if free source code programs before fruit use that idea and have for every term
>>>>endgame evaluation and opening evaluation.
>>>>I use it for some things and I learned the idea from fruit but most of my
>>>>evaluation does not use that idea and I may rewrite the evaluation and test.
>>>>>You must propose something better.
>>>>>Superior evaluation?
>>>>>That code is trivially small.
>>>>>So, small is beautiful?
>>>>bigger has the potential to be better but it is not always better.
>>>>I believe that Rybka's evaluation is even better than fruit's evaluation but
>>>>fruit's evaluation is better than the evaluation of most top programs including
>>>A strong point of Fruits eval is that it is more accurate than it is deep.  Many
>>>people think they will have a better eval by having more knowledge but end of
>>>having bad chess knowledge that does not work well this other knowledge in the
>>Perhaps some kind soul could just take the Fruit 2.1 eval and implement
>>it in their program and tell us the difference in Arena-play for the two
>>of them in a round-robin with many others.
>>Any takers?
>I do not think that it is an easy job to do it without bugs.
>I think that the best plan to do it has the following steps:
>1)translate fruit's evaluation to human language.
>2)modify fruit to calculate some type of perft function on it's evaluation
>3)implement every component of fruit on your program
>4)check that your program has no mistake in predicting fruit's evaluation by
>calculating the same perft function on fruit code.
>If somebody does steps 1 and 2 then it is going to encourage me to try 3 and 4.

One doesn't have to be bug-free to prove that a direction is better.


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