Computer Chess Club Archives


Search

Terms

Messages

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

Author: Omid David Tabibi

Date: 14:01:11 11/21/02

Go up one level in this thread


On November 21, 2002 at 16:55:04, Tony Werten wrote:

>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.
>

You mean you got an average of 5 zugzwang indications per second in middle
game?!!! Then your program has instabilities which cause a huge number of
needless re-searches due to false zugzwang alarm. Turn off your zugzwang
detection at once!


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



This page took 0 seconds to execute

Last modified: Thu, 15 Apr 21 08:11:13 -0700

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