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Subject: Re: shredder 8 and weird PVs? (sandro?)

Author: Sune Fischer

Date: 02:40:07 01/20/04

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On January 19, 2004 at 21:41:57, Robert Hyatt wrote:

>On January 19, 2004 at 20:09:08, Sune Fischer wrote:
>
>>
>>How can it be nonsense?
>
>Same way I described previously.  You reach positions that were not searched
>with the same "criteria" as when the PV was searched...

So?
My evaluation is not path dependent either.

Are you saying a 5 ply PV on position X is good, but when we later in some other
parts of the tree search X with ply 5 or above the PV will be nonsense?

I think you need to explain that to me very carefully.

>>Let's say you pick up a single pv move and then qsearch is called.
>>That would end the pv.
>>
>>The pv might lead to a bad position now, but it can't be considered nonsense
>>when you know what your qsearch can and can't resolve.
>
>If you don't hash the q-search, then obviously the PV will _never_ have any
>q-search captures in it.

I wouldn't want it to, I want to know where the search ends and qsearch begins.
That is important if you want to interpret the PV correctly.

>But when I was doing this, I did hash in the q-search.
>The same problem arises irregardless.  Prior to the q-search, you can overwrite
>stuff.  When you probe for "imaginary" positions beyond the end of the current
>hash-table-hit position, you can get anything.  Good moves.  Moves that don't
>go with the current PV.  And with today's Crafty I would get no q-search moves
>at all, and they are often critical to see.

I suspect your search is broken then.

If you terminate a leaf position because you've run out of depth and you have in
hash that position stored with a decent depth, why not use that information to
get a more accurate score back down the tree?

Something is fishy here.

-S.



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