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Subject: Re: null-move vs non-null-move

Author: Vincent Diepeveen

Date: 04:56:34 10/11/02

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On October 10, 2002 at 03:05:28, Tony Werten wrote:

nullmove improves branching factor, so it isn't 2 ply.
The more efficient you normally search, the more it
improves branching factor, the bigger the difference
when you get a bigger amount of nodes.

4.2 (my branching factor with hashtables and fullwdith)

versus branching factor

2.8-3.2 (branching factor what most get with nullmove)

is going to pay off each ply extra you get.


>On October 09, 2002 at 23:06:48, Robert Hyatt wrote:
>
>>
>>
>>I had to stop the experiment sooner than I wanted, but I did find some
>>interesting things out.
>>
>>1.  at _very_ fast time controls (40 moves in 1 minute) null-move completely
>>destroys non-null-move
>>by a ridiculous margin.  (this ended something like 60 wins, 5 losses, 8 draws)
>>
>>2.  At longer time controls (40 moves in 10 minutes) non-null-move catches up
>>somewhat.  It still loses
>>far more than it wins, but not _nearly_ so bad as test 1.  (this was closer, but
>>with fewer games played)
>>
>>3.  At 40 moves in 60 minutes, things close up even closer as the data I
>>previously posted shows.  The
>>margin ended up at 13.0  /  22.0 in favor of null-move. (null won 8, lost 4,
>>drew 10)
>>
>>4.  I wonder what would happen at longer time controls.  Note that these were
>>run on 550mhz processors, going to cpus 4x faster might close the gap even
>>farther...
>>
>>food for thought...
>>
>>I don't know what 13/22  turns into, rating wise,  18/24 would be +200, so this
>>is significantly less than
>>+200 overall.
>
>Can't say I'm suprised. If nullmove gives 2 ply (wich is what is generally
>accepted ) then you're basicly doing (n vs n+2) matches wich get less unequal
>with bigger n.
>
>Tony



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