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Subject: Re: root search ordening

Author: Robert Hyatt

Date: 08:21:48 05/02/01

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On May 02, 2001 at 10:08:09, JW de Kort wrote:

>dear friends,
>
>A few weeks ago i posted a question about cutting my qsearch. With the valuable
>information you send me i have been able to get a serious reduction for wich i
>want to thank all to people who helped me realize this.
>
>Later i realizes that up till now i have not paid much attention to the move
>order in the root. The program calculates all the moves and starts the iteration
>at 1 ply in the order in which the moves are found. If i move is found to be
>better than all the previous moves tried, this move is placed in front and all
>the others are shifted one place lower in the order. This gives some kind of
>ordering after a few iteration.
>
>I noticed that mr Hyatt uses a far more advanged methode of ordering but his
>methode is not clear to me.
>
>Also i ask myself if it it worth the effort to try to do a good root move order.
>
>
>I hope some one can help me
>
>Thanks in advance
>
>Jan Willem


Mine is easy to do... and dates back to the early days of Cray Blitz, so it
has been tested quite extensively...

I save the nodes searched for each root move.  For the PV move (the best move
after iteration N) I set its node count to something larger than any other move,
then I simply sort on node counts.  This puts the PV from iteration N-1 first
when we do iteration N.  If you change your mind at N-1 once, then the original
best move plus the new best move will have the two highest node counts and they
will be first.  Etc.

Simple and effective.



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