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Subject: Re: To Dr. Hyatt:

Author: Robert Hyatt

Date: 19:42:54 02/15/04

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On February 15, 2004 at 18:24:49, Jaime Benito de Valle Ruiz wrote:

>I think most of us know that you are an experienced programmer/teacher, but it's
>just your opinion after all.
>I find interesting what you mentioned about the analysis of the binary of this
>Danchess program. Except for some hackers, or some disassembly code freaks, I've
>very few people capable of analysing binary files that way. Actually, I find it
>very revealing.
>I don't know what's the method you use to find these similitudes, but I'd bet
>that my code (which is over 90-something % original) would have nearly no
>coincident matches with your Crafty, no matter what you do to find them. It's
>not a scientific method, I know, but finding a sequence of bytes matching both
>two engines' code have to be more than a coincidence, in my opinion. As you
>mentioned before, implementing the same algorithm the same way by different
>people is almost a miracle, but getting the same compiled code byte by byte...
>sounds like a miracle.
>Again, I'm no expert. Just my opinion.
>Regards,


Note that I am talking about data.  IE 64 element arrays with identical
contents.  4K element arrays with identical contents.  Etc.  I don't try to deal
with the actual machine language instructions, different compilers can make that
vary significantly.  But if you look in data.c, chess.h and evaluate.h, you will
see lots of initialized arrays.  Those are one of the things I look for.  There
are others I won't reveal to avoid giving away _all_ my "tricks".  :)

>
> Jaime



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