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Subject: Re: What is perft?

Author: Peter McKenzie

Date: 12:04:20 01/24/02

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On January 24, 2002 at 14:56:59, Russell Reagan wrote:

>So perft is the number of unique positions encountered to a given depth?
>Duplicate positions are not counted twice, as I understand it from your
>explaination.
>
>If it counts the number of unique chess positions, it seems like that would be
>quite a task to generate the entire search tree and store it in memory, remove
>duplicates, and count the nodes. How is this usually implemented?
>
>Russell

'Duplicate' positions are counted twice, although they aren't really duplicates
because they have a different move history.  So if you are doing a 3ply perft
from the root position, you would count e4 e5 f4 and f4 e5 e4 as 2 positions.

See:
http://www.chessclub.com/finger/kiwipete

cheers,
Peter



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