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L+2 group
Keywords: Life & Death
The L+2 group is an L group with a leg on both sides.
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
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.
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).
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.
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. I may be missing the bleeding obvious here - but doesn't Black 6 at 7 give life for black?
Good question. If Dieter -- black will not play at a, but capture -- white 4 is a snapback. I still see this as black lives. Dieter: Yes I noticed, but didn't have the time to re-edit my stuff. Hence the exclamation above.
Bill: How about B 6? Dieter: see above (though you were first). Maybe a white stone at b is appropriate to prevent escape. WRONG. Needs edit Dieter
unkx80: For ease of comparison I added the marked stones.
Bill: Maybe it's too late at night, but what's wrong with a ( unkx80: Oops, I am the one who has gone blur. Bill: Rare for you. :-) unkx80: No, not rare for me. I am blur all the time. =P
In this case I added the marked stone. Now 2. Attacks from within
Here a and b become miai.
Here a and b become miai. 3. An extra stoneIn many of the variations above, Black suffers from shortage of liberties as soon as one of the circled points is filled by White.
4. Weak leg
If Black has a weak leg, White can kill with a rogue ko.
Black cannot play atari at a because of a shortage of liberties. This is a copy of the living page "L+2 group" at Sensei's Library. ![]() |