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Subject: Re: The reason that gandalf is a good program for analysis

Author: José de Jesús García Ruvalcaba

Date: 09:52:03 11/22/00

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On November 22, 2000 at 12:10:18, Uri Blass wrote:

>I found from my experience that Gandalf does not do preprocessing.
>
>I asked the programmer about it to know if this is always the case(because I
>suspected that maybe there are some rare cases when it is a preprocessor) and he
>told me that Gandalf does not care about the root position.
>
>I think that it is very good for analysis because I can generate a tree and use
>the scores of the program to decide about the move when I cannot do it with
>other programs because the score is not made from the same point of view.
>
>I remember also that Amir claimed that Junior does a little bit of preprocessing
>but he does not like it and thinks to change it
>
>I am interested to know about the behaviour of other top programs.
>I think that it is possible to divide top program by the reply to the question
>if they do preprocessing.
>
>I already know that Rebel and Tiger do preprocessing and I also know that
>shredder5 is a preprocessor by my definition(I do not have it but I asked the
>programmer about it and he told me that shredder5 is not a preprocessor by the
>average definition of it but but there is some preprocessing done at the root).

With so many engines having user-modifiable parameters, I think it is a good
idea that the user is able to switch off any eval asymmetry.

>I also know that crafty is a preprocessor(not by the average definition that I
>do not know).

Crafty turns off some preprocessing in analysis mode. You can get rid of the
king-safety asymmetry by changing one evaluation parameter in the .craftyrc
file. I do not know what is left of asymmetry with these two measures.

>
>I am also interested to know what is the average definition.

It should be something that "less than 5% of the eval is preprocessed", whatever
that means.

>My definition is that if there is some preprocessing done at the root then the
>program is a preprocessor.
>
>Uri

I also believe that doing no preprocessing at all is better for analyisis,
especially for long times.
Obviously that is not enough, a strong engine with little preprocessing should
be better than a weak engine with no preprocessing.
For long time analysis, I believe that a more selective search is better, too.
José.



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