Re: [computer-go] Pattern matching - example play

[Don Dailey <drd@xxxxxxx>]

I  too had  great trouble  with null  move in  GO.  Yes,  I  get large
speedups but  null move isn't so  great when the threats  are slow and
long  term.   In chess,  threats  tend  to  be immediate  and  require
immediate responses.   Even chess programs suffer from  null move when
long slow  burning attacks happen.  I  think the evaluation  has to be
really good to get the most benefit from this kind of pruning, because
null move also  prunes tiny positional threats.  It  won't prune these
too much if the evaluation has some sense about them.

Every time I  try, null move weakens the program.   I believe this can
be fixed.  I just haven't spend  a great deal of time yet getting into
the problem since  my program is not search based.   (I have a version
that is for experimentation.)


- Don



   X-Original-To: computer-go@xxxxxxxxxxxxxxxxx
   Date: Thu, 02 Dec 2004 12:21:29 +0100
   From: Erik van der Werf <e.vanderwerf@xxxxxxxxxxxxxxxxx>

   Hi Vincent,

   You're absolutely right that I can get far deeper using nullmove. 
   Unfortunately however, as I mentioned here before, for reasons I do not 
   yet fully understand nullmove did not increase the playing strength.
   The speed was in the order of Mnps, and the evaluation was of course 
   quite stupid. However, I should point out that these numbers are for an 
   ancient version of Magog which has very little in common with the 
   current version which is at least 5 times slower in nps.

   Erik


   Vincent Diepeveen wrote:
   > With nullmove R=3 and some selectivity and good hashtables you should get
   > far deeper depending upon the total nodes you see.
   > 
   > What's the nps you get and what time does it allocate for the first few 
   > moves?
   > 
   > Vincent
   > 
   > At 00:48 2-12-2004 +0100, Erik van der Werf wrote:
   >  >Chris Fant wrote:
   >  >> 9 ply full width on 9x9?  Certainly not near the beginning of the game.
   >  >
   >  >It depends on the time settings. For tournament play it was probably a
   >  >bit less in the opening and a bit more towards the end.
   >  >
   >  >E.
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