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Subject: Re: Don't try this at home

Author: José de Jesús García Ruvalcaba

Date: 08:21:32 08/06/01

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On August 06, 2001 at 02:51:21, Mark Longridge wrote:

>I recently updated my book for crafty by including all the games it's ever
>played, including some pretty bad ones.
>
>I started with all.pgn and inside crafty I typed:
>
>book create all.pgn 80 1 55
>
>Now, my understanding was that the last argument meant "prune everything that
>did not win 55% of the time.

It does not mean that. It means "prune everything that does not win at least 55%
as it loses (and deeper than 80 plies)." So a move which has 55 wins, 100 loses
and some draws will be included.
José.

>Imagine my surprise when my computer as white
>played:
>
>1. e4 c6 2. Ke2 d5 3. Kd3 dxe4+ 4. Kxe4
>
>What the???? Fortunately it was an unrated game, which was actually
>an aborted game which never got passed move 5, _but_ when crafty
>does it's result pruning, there is still the case (like this game)
>where there was 1 game played, but no result. The no result games don't
>get pruned, so even if it's the worst chess opening there is, it's
>still included in the book.bin
>
>A bit careless on my part, but I was still surprised because if this
>line has 0 wins, it's win percentage is 0% and therefore should be
>pruned.
>
>Mark



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