Computer Chess Club Archives




Subject: Re: What approach do you use to handle castling/en passant for repetition?

Author: Daniel Clausen

Date: 11:31:59 02/27/00

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On February 27, 2000 at 14:03:11, Richard A. Fowell ( wrote:

>On February 27, 2000 at 11:19:04, Daniel Clausen wrote:
>>>Which chess programs (other than Screamer) get these right?
>>Not that anyone cares, but my engine gets these right. :)
>Actually, I care - for two reasons. First, it is nice to think that I'm
>not the only one to think it is worth doing this right. Second, it might
>help other programmers address this if those who do handle this could
>present a simple way of doing so.
>So - what do you use? Robert Hyatt says he includes castling rights/en passant
>in his hash. Is that what you do?

Yes, I include these too in the hash value. (side to move also) The problem if
don't include these in the hash as well is not only that repetition-check is not
100% correct but also that the usage of the hashtable itself is (a lil) broken.

I'm aware that this is not "a big deal" but I try to fix at least the known bugs
in my engine. :-)

Kind regards,

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