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Subject: Re: Null-move R=? question

Author: Robert Hyatt

Date: 06:34:45 09/29/99

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On September 29, 1999 at 01:20:45, Gian-Carlo Pascutto wrote:

>On September 28, 1999 at 15:43:43, Robert Hyatt wrote:
>
>>On September 28, 1999 at 13:42:00, Gian-Carlo Pascutto wrote:
>>
>>>
>>>Also, does the actual depth the program reaches play part in
>>>this consideration ? (e.g. if you only get 5 ply then R=2 or
>>>R=3 are out of the question?)
>>>
>>
>>they are _very_ dangerous at that depth.. because any null-move will
>>take you right into the q-search, which is pretty simple-minded.  It works
>>far better at deeper depths...
>
>Ok so what about deciding the R factor by looking up how many plies
>there are still below the null-move search ? i.e. trying to ensure
>there is always a non-null move search in the null-move search (ahem)
>This seems workable as it always catches at least the simple one-move
>threats.
>
>Is something like R=1 doable for 4-5 ply searches ? At what depth can
>one consider taking it to R=2 ?
>
>--
>GCP

1.  I tried the R=2/R=1 trick...  ie if depth > 2 use R=2, else use R=1, so
that you always have a non-null on the end.  That hurts performance badly.

2.  R=1 is safer, but it turns a 5 ply search into 4 plies or less (if you
use recursive null-move).  But on any reasonable hardware you should _never_
see 5 ply searches.  IE on ICC in blitz games, I generally see at least 8 and
normally 9-10 or more...



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