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Subject: Re: Move ordering at root

Author: Robert Hyatt

Date: 11:56:39 04/06/04

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On April 05, 2004 at 16:29:00, Gerd Isenberg wrote:

>On April 05, 2004 at 15:51:43, Robert Hyatt wrote:
>
>>On April 05, 2004 at 15:02:56, Gerd Isenberg wrote:
>>
>>>On April 05, 2004 at 14:11:34, Robert Hyatt wrote:
>>>
>>>>On April 05, 2004 at 12:27:50, rasjid chan wrote:
>>>>
>>>>>On April 05, 2004 at 11:05:30, Robert Hyatt wrote:
>>>>>
>>>>>Thanks, but I don't need to test yet as you have tested !
>>>>>
>>>>>I think using nodes searched should be good.
>>>>>If a move fails low with very few nodes searched, it probably
>>>>>mean being rejected easily, so sort low.
>>>>>
>>>>>Rasjid
>>>>
>>>>Correct most of the time.  Sometimes a move will have a high node count just
>>>>because there are lots of checks and extensions.  But I've been sorting by node
>>>>counts for 15+ years with good results, of course forcing the PV move to always
>>>>be at the top regardless of its node count...
>>>>
>>>
>>>I use node count per root move too.
>>>What about following "enhancement":
>>>If PV changes, to store (some) "previous" PV moves and to use them early after
>>>current PV move, regardless of their node counts?
>>
>>
>>It is worth testing.  It didn't work for me in crafty or Cray Blitz, but it
>>might work for another program.  I always had the best luck overall by just
>>using pure node counts...
>>
>>It helps the most when there is a "best" move that you won't find until deeper
>>depths.  It will percolate up the list, iteration by iteration, so that it is
>>near the top on the iteration where it becomes best.  I also use this
>>information in my parallel split/dont-split at the root adaptive algorithm in
>>Crafty...
>
>
>Yes, exactly my experience. Anyway i occasionally noticed a former PV move had
>low node count (e.g. a forced draw line) but a new PV move suddenly fails below
>draw score. Im such cases trying the "safe" drawline earlier may help to waste
>some time.

Those are the cases that blow my adaptive "split/don't-split at the root" SMP
code.  A repetition will produce a very small tree.  If this is best, then most
of the remaining root moves might produce larger node counts, which makes it
look like they are all potential new best moves.  I catch this, but not very
well...





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