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Subject: Re: Hashing rules

Author: Dieter Buerssner

Date: 12:32:59 04/05/03

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On April 05, 2003 at 14:02:09, Russell Reagan wrote:

>You should only hash the en passant square if it is possible for an enemy pawn
>to execute the en passant capture. This means, ideally, that if there is a pawn
>present to make the capture, but it is pinned and cannot legally make the
>capture, that you should not hash the en passant square. Is this correct?

Correct, but not practically important. The pinned case will practically never
happen. I checked this (inside the search, and by looking through a database of
- I believe - 2.8 million games. It never happened ...) If it would happen, I
think the consequences are not very critical anyway.

>4k3/8/8/8/2b5/8/2PP4/4K2R w
>
>Notice that the white king cannot castle since the black bishop attacks f1. If
>this position arose 3 times, but with differing castling rights, then that is
>NOT a draw by repetition. Correct?

This is also my understanding of the rules.

>In short, the rules are...

I agree with your rules.

Regards,
Dieter



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