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Subject: Re: PV during quiescence search?

Author: Dave Gomboc

Date: 14:09:24 03/25/99

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On March 24, 1999 at 22:42:20, Robert Hyatt wrote:

>On March 23, 1999 at 12:18:29, Vincent Diepeveen wrote:
>
>>On March 22, 1999 at 07:57:06, Robert Hyatt wrote:
>>
>>>On March 21, 1999 at 20:05:08, Charles L. Williams wrote:
>>>
>>>>Is it advantageous to keep updating the PV after entering the quiescence search,
>>>>or should this search be kept very simple?  I'm getting ready to add one,
>>>>captures only.  Thanks in advance.
>>>>
>>>>Chuck
>>>
>>>
>>>If you don't you won't see the end of the PV when you display it at the root,
>>>and this can make testing/debugging difficult, since you won't have any idea
>>>what the complete path looks like from the root to the position where you did
>>>an Evaluate() and then accepted that score.  In fact, your entire PV will have
>>>problems if you don't 'latch it' at the precise instant the score is 'ok'.
>>
>>Sure. an easy solution is there however: if you get your PV from the
>>hashtable and if you are using several probes at the hashtable,
>>then you can get the PV out of the hashtable and this includes then the
>>q-search too.
>>
>>Quick and easy!
>>
>>Greetings,
>>Vincent
>
>
>It's easy if you can be _sure_ you won't overwrite a PV hash entry.  IE how many
>times do you get the first result back quickly, then do a bunch of searching on
>later moves because they have lots of checks that produce lots of extensions.
>
>What do you do if the PV gets overwritten before you need it?  I tried this a
>long time ago.  And didn't like the result.  We back up the PV so infrequently
>I can't really measure the time it takes anyway...  it is very minimal...

I would appreciate it if someone described a way to ensure that hash positions
belonging to the PV do not get overwritten without adversely affecting general
performance.  As things stand I am tracking the best move at the root
separately, because occasionally my root position gets trashed.

I am using replacement scheme BIG-1 (q.v. Dennis Breuker's Ph.D. thesis).

Dave Gomboc



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