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Square nine in the corner
Path: LifeAndDeath · Prev: GunEight · Next: EightPointEyePossibleKo Path: SecondCourseOnKo · Prev: SolutionToJfc001 · Next: KarlKnechtelSKoStory
Keywords: Life & Death, Ko
Square nine in the corner is related to the carpenter's square.
1. No outside liberties
When there are no outside liberties, White can turn this into sente seki [1]. The vital point (obviously) is a.
The points Karl Knechtel: Coincidentally, I was studying this eye space earlier today with a friend on LGS...
This way avoids the ten thousand year ko as well. Note that Black cannot resist White's attempt later by filling the ko in response to the approach:
Now Black's eye space is almost filled with a bulky five, and Black dies.
This becomes seki too, but if Black omits 6, the ko started at
This variation also becomes seki, but White ends in gote.
Black trying to avoid seki by taking away the eye is not a good idea because it becomes seki anyway and Black takes gote too. 2. One outside liberty
With one outside liberty the same main line applies, except that White must play in gote at 3. Two or more outside liberties
With two or more outside liberties, the attempt to make seki fails. [1] Bill: This position is hyperactive, depending on who is komaster. If Black is, or if neither player has any ko threats, White can make seki in gote.
Think about it. What does White threaten?
White can try
This leads to a 10,000 year ko, which White will be reluctant to start. Or White can play at a to preserve the seki.
When White is komaster, things are trickier. White threatens By the same logic, Black should normally reply to White's invasion, setting up a ko to lose while there is still time.
After White starts with When he cannot get so much in return for the ko, Black should usually make seki in gote, as shown in the Main Line diagram. Discussions about this shape in KGS's English room on 23/6/3 suggested the name 'Peachy 9' for this shape. (As in 'Everythings peachy', and not as in 'It's all gone pear shaped'. Perhaps the following shape could be called a pear shape...)
Path: LifeAndDeath · Prev: GunEight · Next: EightPointEyePossibleKo Path: SecondCourseOnKo · Prev: SolutionToJfc001 · Next: KarlKnechtelSKoStory This is a copy of the living page "Square nine in the corner" at Sensei's Library. ![]() |