Computer Chess Club Archives




Subject: Re: Proving something is better

Author: Vincent Diepeveen

Date: 16:20:12 12/17/02

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On December 17, 2002 at 18:34:46, Uri Blass wrote:

>On December 17, 2002 at 18:21:28, Uri Blass wrote:
>>On December 17, 2002 at 18:11:20, Vincent Diepeveen wrote:
>>>On December 17, 2002 at 17:30:36, Bruce Moreland wrote:
>>>if you go back in time a bit you see that i had
>>>major problems with Omids article and posted it here.
>>>there is more than just the problems you see there.
>>>also look at his homepage and get the positions he tested
>>>and then look to his node counts. for a mate in 2 position
>>>where i need like a couple of hundreds of nodes to get to 10 ply
>>>he needs 10 million nodes. then R=3 reduces that more.
>>>also his implementation is buggy of course. it doesn't take into
>>>account problems with transpositions. a classical beginners problem.
>>>But most important is that verification search is not something new
>>>it is a buggy implementation of something already described years ago
>>>with only 'novelty' that omid turns off nullmove *completely*
>>>after he finds a nullmove failure.
>>No he does not.
>>There is no point in the tree that he turns off nullmove completely.
>To be more correct he turns off null move only in some cases when the remaining
>depth is 1 so there is no time for verification search but when the depth is big
>most of the nodes when the remaining depth is 1 come only after null move so
>verification search is not needed and again he is using null move.
>When the depth is big enough he is doing normal null move with R=3 in most of
>the nodes.

you should realize what verification search does.

please write it out for a search X what it does and you'll see that it's
just a bad form of adaptive nullmove the first so many 'verifications'.

the overhead verification search then has when it backs up the tree then
later is of course the extra overhead it has compared to adaptive nullmove,
without that this solves more.

and it is trivial that if i nullmove less that i solve more positions
than the same R does for nullmoving more.

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