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Subject: Re: root search ordening

Author: Ulrich Tuerke

Date: 08:36:08 05/02/01

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On May 02, 2001 at 11:21:48, Robert Hyatt wrote:

>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.

This way, you will have heavily extended root moves rather early in your move
list. These moves must not always be good.

Don't you regard this as a draw-back ?

The advantage is perhaps that nice tactics (checking sacs ...) will be seen
early.

Uli



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