RTG Problem 12 / Attempts

First instinct  

The 1-2 point doesn't look like it will make Black 2 eyes, so lets try something else:

Alternative A  

After Black's second eye has collapsed

Alternative B  

Black doesn't have enough time to save both eyes here, so white will take one either with or by playing should black neglect it.

One last try  

is forced, because black will immediately live by playing it. A, B and C all look miai to keep black dead

Another chance  

Shaydwyrm: here is another interesting move I considered, but it looks like kills.

Follow up  

is strong resistance, but after black is faced with a shortage of liberties.

Follow up  

Willerz: above is wrong -- this makes a and b miai -- Black a makes 2 eyes. Black b makes a seki. So Black can live. White can kill by starting at a.

White 2 at A  

Shaydwyrm: is incorrect, leaves white with no followup.

Not seki  

Shaydwyrm: This is not seki. White can fill black's outside liberties and then play A & B to put black in atari.

Corrected follow-up  

Willerz: Shaydwyrm is right, however I think this makes a and b miai. So Black can live. White can kill by starting at a.

Shaydwyrm: Check the diagram labeled "White 2 at A" above for why white can't kill by starting at A.

Corrected follow-up follow-up  

Shaydwyrm: Aha, but I have considered this as well! forces (in a sense, though black should really tenuki instead of all of these since he's dead), and then the situation is the same as the not-seki above.

This way?  

And if Black replies here?

How about this?  

unkx80: Referring to Alternative A, how is this?

Black has a ko?  

Shaydwyrm: Looks like black has a 2 step ko, since he needs an approach move at a. He should not play his approach move at b, since that gives white a local threat at c. White can play at , then black , white b, black c for a seki if black is komaster.^[1]

Also ko  

Shaydwyrm: here also leads to ko, but it is direct.

Seki?  

Nando: Shaydwyrm, this doesn't look like seki to me...
Shaydwyrm: ...you're absolutely right, I guess doesn't help black after all. at is met with at . So all the ko discussion above is merely academic, how disappointing...

unkx80: Unfortunately yeah... there is no ko here.