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Subject: Re: Some questions about Verified Null-Move Pruning

Author: Tony Werten

Date: 13:55:04 11/21/02

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On November 21, 2002 at 16:19:17, Omid David Tabibi wrote:

>On November 21, 2002 at 16:05:45, Tony Werten wrote:
>
>>On November 21, 2002 at 13:52:33, Omid David Tabibi wrote:
>>
>>>On November 21, 2002 at 13:05:28, Uri Blass wrote:
>>>
>>>>On November 21, 2002 at 09:16:09, Omid David Tabibi wrote:
>>>>
>>>>>On November 21, 2002 at 08:34:36, Uri Blass wrote:
>>>>>
>>>>>>1)I do not find in the pseudo code in figure 3 undo null move.
>>>>>>
>>>>>>I assume that it should be before if value>=beta and after value=-search(...)
>>>>>>Am I right?
>>>>>>
>>>>>
>>>>>That is why it is called *pseudo*-code :-)
>>>>>You have to fill in the obvious parts by yourself...
>>>>>
>>>>>
>>>>>>2)What is the value of the research for tactical strength?
>>>>>>Should it help significantly relative to searching to reduced depth when
>>>>>>value>=beta without research (even when we get value that is less than beta).
>>>>>>
>>>>>
>>>>>I didn't understand the question. Dp you mean doing a shallow search even when
>>>>>we don't have a fail-high report?!
>>>>
>>>>I meant to ask what is the tactical value of the research(You suggested people
>>>>to start with doing it without the research first and only after it works to do
>>>>it with the research)
>>>>
>>>
>>>The re-search is needed only in zugzwang positions. Such zugzwang positions
>>>occur very rarely in midgames; so you can forgo the zugzwang detection re-search
>>>and still benefit all the improved tactical performance.
>>
>>I was quite surprised to see them from the starting position at a rate of 5 per
>>second. Not impressive, XiniX searches 400 Kn/s there, but still surprising.
>>
>
>The rate of what, was 5 per second?

"Zugzwang positions" or rather, positions where nullmove would have given a
cutoff but that after reducing depth and searching gave a score < beta.

Tony

>
>
>>Tony
>>
>>>
>>>
>>>>Uri



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