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Subject: Re: new thoughts on verified null move

Author: Josť Carlos

Date: 09:00:57 11/24/02

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On November 24, 2002 at 10:48:52, Robert Hyatt wrote:

>On November 23, 2002 at 13:38:32, Josť Carlos wrote:
>
>>On November 23, 2002 at 12:53:36, Omid David Tabibi wrote:
>>
>>>
>>>>Nodes to solution should be a better parameter.
>>>>
>>>
>>>Provided that you have a pool of positions that can be solved within a
>>>reasonable time!
>>
>>  You should find them to provide useful data. Tree reduction doesn't mean
>>anything if the solution is not found. Nodes to solution is definetly the
>>important data.
>>
>>  Josť C.
>
>
>Maybe I am overlooking something, but as best I could tell, his new algorithm
>solved more positions than R=2, at the same depth.  _and_ the tree was smaller.
>I don't see how that can be considered a bad way of reporting things.  He ran
>to fixed depth, which I personally think is very reasonable since it provides
>something that can be repeated.  He reported the sizes of the trees, which shows
>that his approach searches a smaller tree than straight R=2.  And he provided
>the number of correct solutions showing that his approach is better than
>straight R=2 also.
>
>To consider his data invalid, you would have to assume one of the following:
>
>1.  His positions are _all_ zugzwang positions, so that any zugzwang detection
>would make it perform better than straight null-move R=2.
>
>2.  Somehow his search makes searching the PV much harder, and the non-PV moves
>much easier, so that reporting the time to solution would somehow show larger
>numbers for his new code, even though the time to complete a depth is lower.
>(I assume the time to depth is lower since he used the same program for both
>and I don't think his NPS will be affected by the algorithm significantly).
>
>I find either of those to be a bit hard to accept, and I concluded that what
>he did worked for him.  Whether it will work for the rest of us or not is
>another thing...

  I agree. Maybe I didn't express correctly. My aswer was directed to the
following statement:

"Provided that you have a pool of positions that can be solved within a
reasonable time!"

  What I meant is: if you use positions that won't be solved by either algorithm
under the chosen testing conditions, the fact that the tree is smaller doesn't
prove anything, as both algorithms will a bad move in that position. So it's
better to find positions where a best move exists and measure time or nodes to
find it.
  Of course, smaller tree plus more solutions is a positive result, but smaller
tree alone isn't.

  Josť C.



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