ChaoSpectre: Fills at ? Do you mean fills the ko? What about 9 here? Also, is it possible to extend from while retaining the corner (S)? I realize that it is not important to the status of the group at this point but...
SnotNose: Looks like ko.
(Moved from /Solution).
Dead, I think - Floris
Dieter: This doesn't prove it is dead, but that it is killable. Is it dead already or unsettled? If so, White can live in ko or live?
unkx80: To put it more directly, when a problem asks for the status of a group, it is effectively asking two questions. 1) Black first to play, what is the best result? 2) White first to play, what is the best result?
SnotNose: doesn't work. Here is one way for Black to kill. There are others.
unkx80: I think kills "unconditionally". What I am not too sure is, what if is played at . I thought it should be a ko.
SnotNose: I think unkx80 is right (that perhaps yields a ko). If Black insists on going for a kill, he will have to ignore I think. (The stones steal the eye at the edge after a throw-in so Black need not respond to right away). Thus, Black can try for the kill with . Continuation in next diagram.
SnotNose: Unfortuneately, Black cannot chase White all the way to the edge because he is short of liberties. I think the best Black can do is jump out with and fight on the outside. Black is full of cutting points so I think White can break out.
I believe this is the only chance for a kill. Since it fails, White should be at worst alive in ko. Here's one way for ko.
SnotNose: is a good move and almost makes a living shape. through are all forced. Any deviation from these lets White live (I think) unconditionally.
SnotNose: Another ko.
SnotNose: Black a, white squeeze at b. No ko this way.
togo: When getting this far, kills ...
togo: ... but White can force a ko on the right side with ( on ).
(more attempts copied from the /solution page)
GustavoBR: i think this is what should happen... please, post your comments =D
El Draco: I think this belongs in the attempts page. The problem asks for the status with both players to move. Also see the page history for what has already been posted on this page (by Floris) and is essentially the same as you entered.
Schinkenjoe If the ladder doesn´t work black can - depending on the situation to the left - just secure at b or - if there is much white to the left - work up to the ko.