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Subject: Re: Move Ordering at the Root

Author: Robert Hyatt

Date: 19:56:34 09/15/99

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On September 15, 1999 at 17:12:16, Dan Homan wrote:

>I was reading the crafty source again the other day and noticed that
>Bob has a special function to improve the move ordering at the root
>of the search.
>
>I really didn't feel like writing such a function last night, but I
>thought instead to use the values returned by the search itself to
>improve the move ordering at the root.  I know that I only get an
>accurate value for the best move, but I thought that my fail-soft
>search might return useful numbers for the other moves as well....
>
>Implementing this was pretty quick and easy: there were a couple
>of pit falls, but the total changes were about 5 lines of code.
>Previously I simply used the same move ordering at the root that I
>use at all other nodes.
>
>The improvement was amazing!  I got a full ply in many positions and
>about a half-ply in many more.   It improved my solution times on WAC
>noticably and seems even better in quiet positions.
>
>I know that my solution was a quick kludge, so I am wondering what
>other people do for move ordering at the root of the search.
>
> - Dan


Are you sure you didn't introduce a bug?  Root ordering is only important
in positions where you change your mind a lot.  If you lock on to one move
and stick with it, it won't do anything to improve the ordering...

a ply sounds really odd as a gain...



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