Valkyria plays J3 or capture the ko, with capturing the ko as the most
common choice. But it always thinks for some thousands of playouts
before it sees a clear win.
Magnus
Quoting David Fotland <fotl...@smart-games.com>:
I checked this position again, and Many Faces finds j3 after a few thousand
playouts, but even at a million playouts (28 seconds) it's only 61%.
From: computer-go-boun...@computer-go.org
[mailto:computer-go-boun...@computer-go.org] On Behalf Of Brian Sheppard
Sent: Saturday, August 15, 2009 8:13 AM
To: computer-go@computer-go.org
Subject: [computer-go] Interesting endgame case
assuming komi 7.5 and Chinese rule, playing at J3 white will win. After J3,
white has 35. It only needs to win the ko or takes two dames. If black
fills
the dame, it loses the ko. If it fills the ko, white can take two dames.
Yes, Chinese and 7.5.
I basically figured that J3 was just another in a long series of stupid
moves by Pebbles, but when it insisted that J3 was winning no matter how
long it searched then I decided to look into it.
J3 looks stupid because it fills territory that O already owns.
J3 wins because it is "reverse sente" (I think this is the right
terminology) because H4 is no longer sente for X. It also gains a
move in the semeai against X's dead stones on the left, so O gains *two* ko
threats.
Just curious: how did you find J3?
1 2 3 4 5 6 7 8 9
A - - O - - - - - -
B X X X O X - - - -
C O O X O X X - - -
D O - O X X - X X -
E - O O O X X O X X
F - X O - X O O O X
G - X O - X O O - O
H O X O - X X O O -
J - - - O X - X O -
O to play
--
Magnus Persson
Berlin, Germany
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