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Subject: Re: Null move reductions

Author: Roberto Waldteufel

Date: 18:21:09 10/04/98

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On October 04, 1998 at 20:24:08, Will Singleton wrote:

>On October 04, 1998 at 19:06:15, Roberto Waldteufel wrote:
>
>>
>>Hi all,
>>
>>I wonder what reductions various programs use for the null move. I reduce by two
>>plies, but I believe a one-ply reduction may be more usual. However, I have
>>found R=2 produces quite good results in my program. I would like to hear of
>>others' experiences.
>>
>>Best wishes,
>>Roberto
>
>
>Amateur uses r=2, and gets about a ply deeper on average.  But I've noticed that
>in positions where there is a clear better move, the node reduction is great,
>and in positions where there is no clear cut better move, the reduction is not
>that great.  Of course, you need it most in the latter situation.  I'm probably
>doing something wrong.  Do you notice anything similar?
>
>Will

Yes, I have noticed more improvement when one move is clearly best than when
there are many plausible candidates, but I had put that down to the nature of
the null move! If there are many plausible moves, then that leaves fewer
terrible moves to cause null-move cutoffs on the next ply. Do you find the same
effect with R=1 as with R=2? I suspect that nodes with a clearly best move are
just plain easier to handle than the rest.

Best wishes,
Roberto



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