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

Author: Uri Blass

Date: 18:39:06 11/21/02

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On November 21, 2002 at 21:21:09, Vincent Diepeveen wrote:

>On November 20, 2002 at 17:51:40, Alessandro Damiani wrote:
>'verified' nullmove, or in a different implementation but
>same algoritm, with just 1 ply reduction is nearly a fullwidth
>I did with a bigger reduction of course. that's also very
>costly compared to R=3. This was just an experiment carried
>out years ago when it was described in ICCA journal. Now
>we have same algoritm in a few lines diff algorithm.
>I do not see how Omid can just suffer 50% slowdown of his
>algorithm. Note he only publishes search depths not
>search times. That is wrong.
>You must publish search times.

I do not see how you can suffer more than 50% slow down.
I think that you simply do not understand the algorithm.

The algorithm does not do nearly full width search because after the first
reduction the search is normal null move pruning without verification.

It did not work for movei or for sjeng but the difference is not as big as you
describe and I suspect that with some modification it may work.

>I suffer plies if i reduce just 1 ply.
>R=2 or R=3 is irrelevant to that.
>>>One final remark: You use standard R = 3 in DIEP. So the search tree constructed
>>>by your program will definitely be smaller than that of verified R = 3. Many
>>>people find standard R = 3 as too risky; but if you are happy with its overall
>>>tactical strength, then I don't recommend you to shift to another method. But
>>>for those who'd like to get greater tactical strength than standard R = 2, and a
>>>smaller search tree than R = 2, I recommend to try verified null-move pruning.
>>Vincent uses R = 3 and complex quiescence search (Vincent, correct me if I am
>>wrong). Maybe your Verified Null-Move gives about the same results like R = 3
>>with a complex quiescence search.
>>_If_ this is true then your approach is simpler and therefore better. Just my
>>two thoughts before going to bed. Good nights.......

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