Computer Chess Club Archives




Subject: Re: Null-Move: Difference between R = 2 and R = 3 in action

Author: Vincent Diepeveen

Date: 02:32:15 07/14/02

Go up one level in this thread

On July 13, 2002 at 21:31:14, Omid David wrote:

there are so many things that work better in just diep
than the 'official' implementation as is in publications.

Now i didn't hit the subject 'forward pruning' yet. Most
of the commercials have put insane much time in forward pruning.

anyone wanting to post something about it:

To just name a few guys who 100% sure read this posting without
majority ever commenting on this, and for sure having a form of
forward pruning which works for them :)

>On July 13, 2002 at 11:57:00, Vincent Diepeveen wrote:
>>On July 13, 2002 at 11:17:12, Omid David wrote:
>>For diep the adaptive nullmove, which i btw used in diep
>>around 1995-1998 already, it was pretty interesting thought
>>back then, but in the end R=3 always worked better.
>Although Heinz was the first to publish adaptive null-move pruning formally,
>many people used it even before that. Donninger told me that in 1993 he used the
>very same idea in NIMZO. In his article Heinz points out that Donninger hinted
>at using R=2 in upper parts of the tree and R=3 in lower parts; but in fact
>Heinz misunderstood Donninger's 1993 article since Donninger suggested exactly
>what Heinz did.
>>I have just to get a good compare run at Jan Louwman's auto232
>>players with diep with 2 versions, the only difference being
>>R=3 versus adaptive nullmove (last 4 plies R=2), and that
>>DIEP then nearly gets a ply less deeply, it definitely was
>>reflected in score. A big problem is to get above that
>>10 simply for DIEP.
>>>On July 13, 2002 at 10:50:52, Robert Hyatt wrote:
>>>>On July 13, 2002 at 02:07:17, Vincent Diepeveen wrote:
>>>>>I still do not understand which positions you talk about which R=2
>>>>>is finding and R=3 isn't.
>>>>Note that he used fixed-depth.   This is therefore not surprising since
>>>>some lines will be searched one ply shallower..
>>>Of course. I merely did something like Heinz in "adaptive null-move pruning" (he
>>>searched to fixed depths of 8, 10 and 12). But to get a clearer distinction, I
>>>turned off checks in qsearch (that means in practice R=3 would perform better
>>>than it did in those tests)

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