RTG Problem 12 / Attempts

Sub-page of RTGProblem12

Mef: I think black is dead

First instinct  

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

Alternative A  

After W4 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 W4 or by playing W3 should black neglect it.

One last try  

W2 is forced, because black will immediately live by playing it. A, B and C all look miai to keep black dead

Another chance  

Shaydwyrm: B1 here is another interesting move I considered, but it looks like W2 kills.

Follow up  

B3 is strong resistance, but after W6 black is faced with a shortage of liberties.

Follow up  

Willerz: B3 above is wrong -- this B3 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: W2 is incorrect, B3 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 B3 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! W6 forces B7 (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?

WillerZ: White a and we're back to where we were just now.

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 W4 at B5, then black W6, white b, black c for a seki if black is komaster.[1]

Black has a ko?  

WillerZ: Doesn't this W6 (instead of a) give White a better result? Also, I am not sure that this W4 is the best W4.
Shaydwyrm: This is not a better result, since black next plays b and has a direct ko instead of a 2 step ko. However, it seems you're right that W4 is not the best, see below.

Also ko  

Shaydwyrm: W2 here also leads to ko, but it is direct.



Nando: Shaydwyrm, this doesn't look like seki to me...
Shaydwyrm: ...you're absolutely right, I guess B3 doesn't help black after all. B5 at W8 is met with W6 at B5. So all the ko discussion above is merely academic, how disappointing...

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

RTG Problem 12 / Attempts last edited by Unkx80 on August 3, 2004 - 20:13
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