Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: new thoughts on verified null move

Author: Martin Giepmans

Date: 08:37:25 11/23/02

Go up one level in this thread


On November 23, 2002 at 08:48:36, Omid David Tabibi wrote:

>On November 23, 2002 at 08:45:00, Uri Blass wrote:
>
>>On November 23, 2002 at 08:11:37, scott farrell wrote:
>>
>>>Just after other people's thoughts.
>>>
>>>I think Omid's work overlooked the adapative null move searching many of us do,
>>>ie. transitioning from r=3 to r=2.
>>>
>>>I think adaptive null move tries to GUESS where to use r=2 to reduce the errors
>>>that R=3 makes. I guess it depends on how often this GUESS is correct, the cost
>>>of the verification search, and how long it takes the adaptive searching to
>>>catch the error at the next ply.
>>>
>>>Has anyone looked at setting the verification search to reduced depth of 2
>>>(rather than 1)? obviously to reduce the cost of the verification search.
>>
>>Omid checked it but you also reduce the gain.
>>
>>I think that I will look for good rules when to do the verification search so
>>the cost will be significantly smaller but the gain is going to be the same in
>>at least 99% of the cases.
>>
>
>I'm currently working on other variations. The initial results are promising.
>
>>Uri

I have done some tests with your method at greater depths.
At depth 12 vrfd R=3 still had an overhead (in terms of treesize) of about
25% compared to pure R=3.
(my engine uses a simple Q-search that shouldn't give problems here)

So the question is if your expectation that the treesize of R=3 and vrfd R=3
converge at greater depths (> 11) really holds.

Needs more testing, I think.

Another point:
I would expect that vrfd R=3 becomes less safe at greater depths.
The subtrees in which you don't verify nullmove (after the verification) become
deeper and I see no reason - on logical grounds - why this shouldn't give safety
problems.
Even if R=3 and vrfd R=3 converge in terms of treesize, the safety (or rather
the lack of it) might also converge ...

In any case, thanks for sharing.

Martin







This page took 0.06 seconds to execute

Last modified: Thu, 07 Jul 11 08:48:38 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.