Computer Chess Club Archives




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

Author: Robert Hyatt

Date: 15:32:33 03/01/00

Go up one level in this thread

On March 01, 2000 at 15:55:39, Daniel Clausen wrote:

>:It is possible to get a good estimate for the relevant probability by dividing
>:the number of games when ignoring the EP square caused problems by the number
>:of total relevant games
>Um.. why (the hell ^H^H^H^H^H^H^H^H :) would you want more data about this EP-
>issue? We all agree it *can* lead to problems, we (prolly) all agree it can be
>fixed in a rather trivial way. Why not "case closed"? I dunno about you, but my
>engine is full of non-obvious bugs - I'm happy to fix such an obvious one with
>almost no effort.
>Ok, here's an analogy: For a root position we know that if we choose move A,
>the opponent gets a draw given best play. For move B from the root position
>we find out that there's a move for the opponent which wins our queen. I suggest
>we stop searching move B. Deal? :)
>Kind regards,
> -sargon :)

We also got led astray by mentioning castling in the same post.  Castling isn't
such a problem, since one side can only castle at most one time in any path.
But EP can happen _many_ times in one path, and can continue to happen
throughout the game...

They have different probabilities of affecting the root move.

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