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The Long L-Group
Path: LifeAndDeath · Prev: TheLGroupIsDead · Next: BentFourInTheCorner
The black shape in this corner is the long L-group. It controls more corner space than the L-group, and this greatly improves its chances for survival.
This is White's best attack. She produces a somewhat strange ko in the corner. This is known as a Ten Thousand Year Ko...
This diagram is a modified one with extra liberty at a for the black group. Note that black is unconditionally alive.
The attack by white 1 and 3 fails. Black have an excellent way to live - by playing at 4, aiming to play at a...
If white answers at 5, black will play at 6. The result is a seki, which is considered the same as living unconditionally when considered in terms of Life And Death.
The strongest attempt for white is to atari at 5 in this diagram. But black 6 sacrifies yet another stone, and takes back at 8... (Black 8 at 6)
If white plays at 9, black 10 will cause white to be caught with a connect-and-die (a kind of damezumari).
White 9 here won't start a ko either. After black 10, white a, black b, it will be obvious that black is unconditionally alive. The extra liberty comes in very handy here.
There is an extra marked stone that has descended to the edge. White plays first, and black is unconditionally dead.
Black's attempt at a ko becomes a damezumari instead. Note: White 5 can also be played at 7.
Kanazawa Solution 18 includes this variation. The marked black stone creates a defect, and now Black 4 is atari making the previous diagram defunct.
Subsequently, if white plays at 1, black lives with 2 and 4. (White 3 at marked stone)
White descends the other way. Still, white first will kill black unconditionally.
This is also damezumari. Black can't play at a after white 7. Authors: Path: LifeAndDeath · Prev: TheLGroupIsDead · Next: BentFourInTheCorner This is a copy of the living page "The Long L-Group" at Sensei's Library. (C) the Authors, published under the OpenContent License V1.0. |