Gun Six
1. No outside liberties
If there are no outside liberties, this 6 points large eyeshape can be turned into seki. Any of the three marked points accomplishes this result.
Starting at 2-2 gives the same result, but ...
... starting at 1-2 invites Black to make the mistake of answering at 2-2. White 3 makes a bent four in the corner shape, killing Black.
2. Outside liberties
If there is at least one outside liberty, Black is alive with 5 points.
Thanks to the outside liberty, Black can give atari at 4. Without that extra liberty, Black 4 would put himself into atari.
3. Endgame conclusions
When the last outside liberty is filled, Black 1 makes 5 points in gote (deiri counting).
(As I don't fully grasp miai counting I'd rather have someone else talk about that.)
- SAS: Note that 5 points is only correct under Japanese/Korean rules. Under almost any other ruleset the deiri value is only 4 points, since Black would have a point in the seki anyway. As usual for double gote plays, the miai value is half the deiri value (so 2.5 or 2).
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