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Subject: Re: when is a clone a clone?

Author: Odd Gunnar Malin

Date: 03:52:45 11/28/03

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On November 28, 2003 at 06:44:48, Tord Romstad wrote:

>On November 28, 2003 at 06:12:43, Odd Gunnar Malin wrote:
>
>>On November 28, 2003 at 05:00:49, martin fierz wrote:
>>>
>>>how much foreign code is allowed?
>>
>>None.
>
>My engine is completely different from Crafty in almost every possible
>way.  I don't have a single bitboard in my code.  I do lots of
>eval-based extensions, reductions and forward pruning.  My qsearch is
>quite big and contains many checks and other non-capturing moves.
>Qsearch is hashed.  My eval is used to locate mate threats, hanging
>pieces, forks, pinned or overloaded pieces and similar tactical motifs.
>My search algorithm is MTD(f) rather than PVS.  In short, my whole
>approach to chess programming is radically different to Bob Hyatt's,
>and there is very little in Crafty's source code which has any interest
>to me.
>
>But still, my 64-bit random number generator is copied directly from
>Crafty's source code.  Does this make my engine a clone?  If you or
>somebody else thinks the answer is "yes", I will consider replacing
>the random number code in my next version, even though it will force
>my users to download the opening book again.
>
>Tord

If you took it as it is without testing, yes I would think so. If you took his
idea and learned it from Knuth's book, I guess it would be right. I did allmost
the same but I stoped because I didn't have the source of his magic numbers or
any other magic number. I added instead the random generator two pages later in
Knuth's book. But I have to admit that I have several random generators masked
out in my code that I put in to check when I have debugged the hash for some
days.



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