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Subject: Re: Detecting three-fold repetition?

Author: William H Rogers

Date: 11:25:00 07/17/00

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On July 17, 2000 at 13:56:46, Dann Corbit wrote:

>On July 17, 2000 at 13:40:28, Tom Kerrigan wrote:
>
>>I've had a number of requests to implement 3-fold repetition detection in TSCP.
>>It's also clear that TSCP would do better in tournaments (although that isn't
>>the goal...) if it could detect these draws.
>>
>>So the question is, is there an easy way to do the detection?
>>
>>In my "strong" program, I just compare hash keys. But TSCP doesn't keep hash
>>keys and I have no intention for it to do so. So is there another way to do it?
>>
>>Thanks in advance.
>
>Just keep an ordered list of the actual EPD positions as the game moves along.
>If you see one occur twice, increment a counter.  If you see it three times --
>draw.  Since there are going to be less than a thousand positions during a game,
>the storage cost will be very small, especially if you keep them in binary
>format.  When you insert a new element, the counter is one.  Pretty easy.
>

If you see that a three time repetition is about to occur and you are not losing
then ajust you eval to make the current move BAD otherwise you can go for the
draw.
Bill

>You could use and EPD bolt-on like the one on my ftp site which will keep your
>part of the code simple, but requires a C++ compiler.  You could retain a C
>interface to the C++ functions by doing extern "C" {} wrappers.



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