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Subject: Re: Question about aspiration search

Author: Fabien Letouzey

Date: 05:32:05 03/25/04

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On March 25, 2004 at 08:11:08, Sune Fischer wrote:

>On March 25, 2004 at 07:47:02, Fabien Letouzey wrote:
>
>>>
>>>So was I.  You have only solved the problem along the PV.  It _still_ exists
>>>along non-PV moves just as I explained...
>>>
>>>this has nothing to do with aspiration issues...
>>
>>Yes of course it does not fix all the problems, I should have stated
>>it.  However I think I gain some "stability" (and a complete PV as a
>>side effect) at the cost of a 1-ply search (sometimes more) all along
>>the PV.  For some reason, I did not consider turning hashing off
>>everywhere in the tree :)
>>
>>The tradeoff in my design is that null-window searches can do what
>>they want (forward prune, be inconsistent, etc ...), and the pv-node
>>search will try to accomodate with that.
>>
>>Fabien.

>I recall having read about something similar, namely extending the PV to make
>sure the line is sound.

>I believe the conclusion was that it didn't work so well, that the PV was no
>more important than the refutations and there was no a priori reason to be
>extending it.

I have read this threat, but what I do is different.
There is no extra depth anywhere.
My 1-ply thing is because I don't use hash-table values at PV nodes, so Fruit
needs a 1-ply search to find it again (and 1-ply search at the PV node son etc
...).  At each PV node (usually a single line), all siblings are searched.

Fabien.




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