[Computer-go] AlphaGo rollout nakade patterns?

Roel van Engelen ich.bun.ut at gmail.com
Tue Jan 31 07:32:56 PST 2017


@Brain Sheppard
Thanks that is a really useful explanation!
the way you state: "and therefore a 8192-sized pattern set will identify
all potential nakade." seems to indicate this is a known pattern set? could
i find some more information on it somewhere? also i was unable to
find Pebbles,
is it open source?

@Robert Jasiek
what definitions/papers/publications are you referring to?

m.v.g. Roel

On 24 January 2017 at 12:57, Brian Sheppard via Computer-go <
computer-go at computer-go.org> wrote:

> There are two issues: one is the shape and the other is the policy that
> the search should follow.
>
> Of course the vital point is a killing move whether or not a group was
> just captured. So it is possible to detect such shapes on the board and
> then play the vital point.
>
> It is an entirely different thing to say when a rollout should look for
> such features. Rollouts are complicated; playing the "best" play does not
> always make your search engine stronger. Of course, there is a question of
> the time required for analysis. And then there is the question of "balance".
>
> "Balance" means that the rollout should play "equally well" for both
> sides, with the goal that the terminal nodes of the rollout are accurate
> evaluations of the leafs of the tree. If you incorporate all moves that
> punish tactical errors then sometimes you can get unbalanced results
> because you do not have rules that prevent tactical errors from happening.
>
> A common rule for nakade is to only check after a group is captured. The
> point is that the vital point is otherwise not motivated by any heuristics,
> whereas most other moves in capturing races are suggested by local
> patterns. My understanding of Alpha Go's policy is that they were only
> checking for nakade after captures.
>
> The "center of a group of three" rule is a separate issue. My recollection
> is that this pattern should be checked after every move, and that was a
> discovery by the Mogo team.
>
> Note that there are often subtle differences for your program compared to
> the published papers.
>
> Best,
> Brian
>
> -----Original Message-----
> From: Computer-go [mailto:computer-go-bounces at computer-go.org] On Behalf
> Of Gian-Carlo Pascutto
> Sent: Tuesday, January 24, 2017 3:05 AM
> To: computer-go at computer-go.org
> Subject: Re: [Computer-go] AlphaGo rollout nakade patterns?
>
> On 23-01-17 20:10, Brian Sheppard via Computer-go wrote:
> > only captures of up to 9 stones can be nakade.
>
> I don't really understand this.
>
> http://senseis.xmp.net/?StraightThree
>
> Both constructing this shape and playing the vital point are not captures.
> How can you detect the nakade (and play at a in time) if you only check
> captures?
>
> --
> GCP
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