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L+2 group
Path: LifeAndDeath   · Prev: L1Group   · Next: LongLGroup
    Keywords: Life & Death

The L+2 group is an L group with a leg on both sides.

[Diagram]
Diag.: L+2 group

The L+2 group is alive. The corner territory can be reasonably counted as 6 points. We will have a look at: the defense against the hane from either side; how to deflect attacks from within; and the status of this group when White has a stone on either of the marked points.



1. Defence against a hane

[Diagram]
Diag.: First hane

Against the hane from the short side, one should defend at the 1-2 point. Now there are two sure eyes at the circled points.


[Diagram]
Diag.: First hane: failure

Answering at the 2-2 point leads to seki - or to ko if that is what Black really wants (see bent four in the corner).


[Diagram]
Diag.: Second hane

Against the hane from the long side, one should defend at the 2-2 point. Now there are two sure eyes at the circled points.


[Diagram]
Diag.: Second hane: failure

Answering this hane at 1-2 leads to disaster. Black can't play 8 at a because of shortage of liberties. If Black 6 at a, White 7 at 6 kills: see rectangular six in the corner.


[Diagram]
Diag.: Second hane: failure?

Bill: How about B 6?


2. Attacks from within

[Diagram]
Diag.: Attack at 1-2

[Diagram]
Diag.: Attack at other 1-2

[Diagram]
Diag.: Attack at 1-3

Here a and b become miai.


[Diagram]
Diag.: Attack at 2-2

Here a and b become miai.



3. An extra stone

In many of the variations above, Black suffers from shortage of liberties as soon as one of the circled points is filled by White.

[Diagram]
Diag.: L+2 group



4. Weak leg

[Diagram]
Diag.: L+2 group with a weak leg

If Black has a weak leg, White can kill with a rogue ko.


[Diagram]
Diag.: White makes a rogue ko

Black cannot play atari at a due to a shortage of liberties.



Path: LifeAndDeath   · Prev: L1Group   · Next: LongLGroup
This is a copy of the living page "L+2 group" at Sensei's Library.
(OC) 2003 the Authors, published under the OpenContent License V1.0.