1. No outside liberties
This position is hyperactive. Its value and play depends upon the ko threat situation. If White is komaster, she can often make seki with sente.
is the strongest attack. is the point to avoid ko. is necessary or White plays there (or to the right of it) to capture the corner.
at or will also make a seki, but White would get an extra ko threat.
Nikok34 (KGS) : Can't in this position White can make a bent four in the corner with 1-1?
willemien : No not all bent four's are bent four in the corner. If White plays 1-1 and Black captures, you get the "Not corner bent four 3" on the bent four in the corner page and Black is alive.
Nikok34 : Now I see why ... thanks.
at the 2-2 point invites an approach ko. Black takes first and White owes an approach (), but nevertheless ko.
If after , White gets to play (the approach move), the ko becomes direct.
in this variation invites a seki. Without either player can make a throw-in ko.
The Count: This isn't necessarily a mistake, is it? If White has one big ko threat and no others then White can't win the approach ko above, but can win the throw-in ko, and so Black will play and White will make seki which is better than nothing.
2. Outside liberty
If there is at least one outside liberty, Black is alive with seven points.
Now the marked points all work.
Conclusion for the endgame
and each threaten at least mannen-ko in sente, and threatens to make seki in sente. makes seven points in reverse sente.
For the mannen-ko, the stone in the ko will be black and Black will still have the outside liberty. ( can be either or .)