[computer-go] Congratulations to Crazy Stone!

[Jason House]

On 7/9/07, Nick Wedd <nick at maproom.co.uk> wrote:
>
> In message
> <6054b7b40707090648g52b90b00g39e7c7bdd8a2e266 at mail.gmail.com>, Jason
> House <jason.james.house at gmail.com> writes
> >Open Division Round 5
> >- I personally thought the IdiotBot/HBotSVN game had an interesting
> >end position. Despite the extreme weakness of HBotSVN (simply using
> >the UCB algorithm), the position was problematic for several monte
> >carlo engines. HBotSVN thought it had a 100% chance of victory though
> >the bulk of the end of the game because the random playouts assumed
> >idiotbot would fill one of its eyes.
>
> I am interested to see that UCB does indeed have that effect.  We were
> discussing it this morning, and wondering if a pure UCB program would be
> happy about its opponent have a two-point group, expecting one of them
> to get filled in.
>
> But I doubt this would be of general interest to programmers?
>

UCB has nothing to do with it.  UCB is simply 1-ply UCT.

The interesting part is the anti-eye-filling rule used as part of the MC
playouts.  As far as I know (and this was mostly confirmed in the computer
go chat room), eye-points are detected by the same means.  All adjacent
points (4 directions) must be the same color, and the surrounding points (8
directions) must have no more than one break, where the edge is included.

Here are ALL of the legal eye patterns if you allow them to be rotated.
XXX
X X
XXX

XX
X X
XXX

XXO
X X
XXX


|XX
| X
|XX

|XX
| X
|---


The edge group in the game was something very close to the following:
|XXX
|X X
| XX
|XX

Note how the lower eye fails to be detected as an eye.  There are other
examples that can be created that are not detected as eyes, but this is what
came up in the game.
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