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

Author: Peter McKenzie

Date: 12:23:54 11/26/02

Go up one level in this thread


On November 26, 2002 at 12:26:58, Omid David Tabibi wrote:

>On November 26, 2002 at 12:18:10, Omid David Tabibi wrote:
>
>>On November 26, 2002 at 07:09:07, Gian-Carlo Pascutto wrote:
>>
>>>On November 25, 2002 at 22:32:28, Dave Gomboc wrote:
>>>
>>>>>No. Maybe I shouldn't have mentioned it - it's not really fair
>>>>>to Omir as he does publish his stuff.
>>>>
>>>>In that case, I'll take it as a courtesy if you don't criticize any work I
>>>>happen to publish because it uses node counts instead of wall clock timings.
>>>
>>>I don't think it's fair to say 'what you published is crap, I have
>>>something much better but I'm not telling you what and I'm not going
>>>to publish it or post test results from it'.
>>>
>>>I think it's fair to say 'what you published is crap because you did
>>>not test it correctly and you compared only to inferior methods whereas
>>>better methods were already known and published'
>>>
>>>I don't think it's fair to criticise Omir because his scheme does
>>>not work in my engine. I think it's fair to criticise him because
>>>he did not include Heinz scheme in his tests.
>>>
>>
>>What do you mean by "he did not include Heinz scheme in his tests"?
>>
>
>Oh, if you mean adaptive null-move pruning, I didn't consider it since its
>tactical strength is not more than standard R=2.

I'm not exactly sure what you mean by 'tactical strength'.  I suspect you mean
'can solve more test suite positions at the same depth'.  That can be useful for
certain comparisons but isn't a good absolute measure of how good an algorithm
is.

Assuming that verified nullmove is tactically stronger than standard R=2, then
it must be tactically stronger than adaptive nullmove (at the same depth).  Does
this make it better?  Of course not because adaptive nullmove may, for example,
use significantly less nodes at large depths.  If this is the case (I don't know
if it is) then another comparison method may need to be used.

The main thing is that it is accepted that adaptive null-move pruning is better
in real games than standard R=2, and surely that is the most important thing?
Test suites are a means to an end, not an end in itself!

Personally, I am only interested if verified nullmove is better than adaptive
nullmove in real games.  Now it seems you have shown that for your program
verified nullmove is likely better than standard R=2 in real games (because it
is tactically stronger, AND has smaller trees), which is interesting but not
really crucial because we already have something else better than standard R=2.

Well done on writing the paper, it has certainly stimulated interest which is a
very good thing.  But a comparison between adaptive nullmove and verified
nullmove would have made it much more interesting.

Regards,
Peter

<snip>



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