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Subject: Re: Move Ordering at the Root

Author: James Robertson

Date: 19:47:53 09/15/99

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On September 15, 1999 at 22:37:34, Will Singleton wrote:

>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
>
>I find it odd that you'd get an improvement with that scheme -- what were you
>using before?
>
>I now use the node-count method, which worked better than my previous method,
>which I don't remember right now (might have been your new one).
>
>Will

I don't use any root-ordering method. How much does it help you? A full ply or
even half a ply or even a quarter of a ply would be wonderful.

James



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