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-boun...@computer-go.org] On Behalf Of
Gian-Carlo Pascutto
Sent: Tuesday, January 24, 2017 3:05 AM
To: computer-go@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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