-----Original Message-----
From: [EMAIL PROTECTED]
To: computer-go@computer-go.org
Sent: Tue, 10 Apr 2007 2:43 PM
Subject: Re: [computer-go] The physics of Go playing strength.
On Tue, 10 Apr 2007, Christoph Birk wrote:
> On Tue, 10 Apr 2007, Hideki Kato wrote:
>> According to the report on MoGo (RR-6062), its playout part seems
>> pruning not interesting moves using patterns.
>
> Yes, but the UCT part will (sooner or later) explore EVERY path.
Well, really it could be either way. In the simplest case, UCT builds a
tree without skipping any legal nodes. In that case, the playout type doesn't
matter and the engine's convergence in the limit is assured. (Of course we'll
all be dead by then...)
But some implementations do decline to explore some legal nodes in the
tree, particularly for larger board sizes. For instance, some versions of Mogo
constrained some internal nodes in the tree to those with moves within a local
neighborhood of the previous move. IIRC their RR-6062 report touched on this.
In the current version of AntIgo, I use patterns learned from the (heavy)
playouts to bias the selection of moves in lightly visited internal nodes. And
there are a lot of other little tricks that can potentially alter the
asymptotic properties of the algorithm. I doubt it matters, because any such
trick I can think of, could be massaged into a form where the engine would
converge anyway.
It all comes down to the terminology we're using being not so precise or
universally accepted.
- Dave Hillis
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