[Welcome to Sensei's Library!]

StartingPoints
ReferenceSection
About


Paths
LifeAndDeath

Referenced by
TenThousandYearKo
LGroup
KanazawaProblem20
KanazawaSolution18

 

Long L Group
Path: LifeAndDeath   · Prev: L2Group   · Next: TripodGroup
    Keywords: Shape, Life & Death

[Diagram]
Diag.: The long L group

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.


[Diagram]
Diag.: a strange ko

This is White's best attack. She produces a somewhat strange ko in the corner. This is known as a ten thousand year ko.



[Diagram]
Diag.: With an extra liberty

This diagram is a modified one with extra liberty at a for the black group. Note that Black is unconditionally alive.


[Diagram]
Diag.: Black can answer at 4

The attack by White 1 and 3 fails. Black has an excellent way to live - by playing at 4, aiming to play at a...


[Diagram]
Diag.: Variation 1: seki

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.


[Diagram]
Diag.: Variation 2: still alive

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)


[Diagram]
Diag.: Variation 2a: oiotoshi

If White plays at 9, Black 10 will cause White to be caught in an oiotoshi (a kind of damezumari).


[Diagram]
Diag.: Variation 2b: big capture

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.



[Diagram]
Diag.: White descended to the edge (1)

There is an extra marked stone that has descended to the edge. White plays first, and Black is unconditionally dead.


[Diagram]
Diag.: White descended to the edge (1)

Black's attempt at a ko becomes a damezumari instead.

Note: White 5 can also be played at 7.


[Diagram]
Diag.: White descended to the edge (1 var)

Kanazawa Solution 18 includes this variation. The marked black stone creates a defect, and now Black 4 is atari making the previous diagram defunct.


[Diagram]
Diag.: White descended to the edge (1 var)

Subsequently, if White plays at 1, Black lives with 2 and 4.

(White 3 at marked stone)


[Diagram]
Diag.: White descended to the edge (2)

White descends the other way. Still, White first will kill Black unconditionally.


[Diagram]
Diag.: White descended to the edge (2)

This is also damezumari. Black can't play at a after White 7.



Authors:



Path: LifeAndDeath   · Prev: L2Group   · Next: TripodGroup
This is a copy of the living page "Long L Group" at Sensei's Library.
(C) the Authors, published under the OpenContent License V1.0.