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Subject: Re: when is a clone a clone?

Author: Peter Fendrich

Date: 04:42:16 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

I did the same in Terra with the 32-bit random function. The 64-bit is just
glueing 2 32-bit numbers. I just had to do some small adjustments to fit my
OO-approach.
I suppose that we need Bob's ok in order to live with it...
I've spend hours and hours coding a chess program.
That just can't be a clone!

Another Crafty code snippet that probably is found in a great number of programs
is the Winboard-Read-Function (maybe even some commercials). That one is
published in this forum several times and should probably be regarded as public
code but I'm not sure.
I changed mine when Terra became threaded.
/Peter





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