Many Faces of go uses alpha-beta full board search with null move for the
levels that don’t use monte carlo search.  Monte carlo search is used in the
2 kyu level.  Alpha beta is used by 4 kyu to 9 kyu.  The weaker levels just
do a single ply search.

Null move helps, but I never tested how much it helps.

David

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Rémi Coulom
Sent: Saturday, December 20, 2008 7:04 AM
To: computer-go
Subject: Re: [computer-go] Nullmoves in MCTS and UCT?

Ingo Althöfer wrote:
> Question: Have nullmove-concepts been tried
> or analysed in MCTS or UCT-settings?
>
> Background of the question: Using alpha-beta tree
> search, the (asymptotic) percentage of nullmove cutoffs
> may help as an indicator for the "naturality" or 
> "interestingness" of a (newly invented) game.
> Unfortunately, it is nontrivial to design "traditional" evaluation
> functions for newly invented games...
>
> Ingo.
>   

Null-move pruning only make sense in alpha-beta. MCTS/UCT are more like 
min-max. They do no alpha-beta pruning, so cannot do null-move pruning.

Still, some programmers tried null move in 9x9 alpha-beta go programs. 
As far as I remember, they got no strength improvement from it.

Rémi
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