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Subject: Re: Verified Null-Move Pruning, ICGA 25(3)

Author: Omid David Tabibi

Date: 12:54:26 11/27/02

Go up one level in this thread


On November 27, 2002 at 15:36:31, Frank Phillips wrote:

>On November 27, 2002 at 15:15:50, Robert Hyatt wrote:
>
>>On November 27, 2002 at 13:48:50, Frank Phillips wrote:
>>
>>>On November 26, 2002 at 20:02:06, Robert Hyatt wrote:
>>>
>>>>On November 26, 2002 at 16:21:00, Omid David Tabibi wrote:
>>>>
>>>>>On November 26, 2002 at 15:58:06, Gian-Carlo Pascutto wrote:
>>>>>
>>>>>>On November 26, 2002 at 15:55:56, Omid David Tabibi wrote:
>>>>>>
>>>>>>>So it is reasonable that on every program starting from a certain depth >adaptive null-move pruning will always construct a smaller search tree.
>>>>>>
>>>>>>Don't you mean the other way around?
>>>>>>
>>>>>
>>>>>Yes :-)
>>>>>
>>>>>Starting from a certain depth, verified null-move pruning will always construct
>>>>>a smaller search tree than the adaptive one.
>>>>>
>>>>>
>>>>>
>>>>>>--
>>>>>>GCP
>>>>
>>>>
>>>> I am doing some testing now.  First thing I noticed is that for WAC, the
>>>>time-squared
>>>>measurement went down very significantly for your algorithm.  And I have not
>>>>modified
>>>>anything such as turning null-move off when low material happens, since your
>>>>idea will
>>>>catch the zug problems.
>>>
>>>Have you tried Fine70?
>>>
>>>Frank
>>
>>Yes...  and I told Omid that this is a strange case as if I allow null-move in
>>pawn-only
>>endings, which turns it on for fine 70 of course, things get wrecked inside the
>>search
>>somehow.  A 45 ply search fails to see that Kb1 wins where normally an 18-19 ply
>>search is enough...
>>
>>
>>>>
>>>>
>
>
>Snap... and I have no idea why.  I thought it was my implementation of a similar
> idea (from Bruce's site) of verification search, but I copied the scheme in
>Omids paper and it does the same.
>

What appears at Bruce's site is the original Goetsch and Campbell idea to detect
zugzwangs. Plenkner (1995) introduced a similar zugzwang detection method.

Verified null-move pruning is different from these methods, for its most
important application is in middle games, constructing a smaller search tree
with greater tactical accuracy.


>Frank



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