BQM 526

    Keywords: Question

Does the 3-3 invasion under this unconventional 4-4 enclosure lead to ko, or can black kill unconditionally?


[Diagram]
Black to move.  

[Diagram]
Black to move.  

I believe that W can live or escape unconditionally. The strongest threats to W would seem to be at a, b, and c. None of those lines seem to lead to an unconditional kill, or even a ko to kill.

tapir: As always all comments without warranty. I don't see how White is going to live unconditionally in the corner after b. However White does not need to live there.

[Diagram]
Even escaping on the side depends on a ladder. black+circle helps here.  
[Diagram]
With black+circle in place Black can play B6, so W7 is not sente and White can't live unconditionally here. Ko next or B8 if White can't make an eye on the edge.  
[Diagram]
White idea - inviting Black to take the stone.  
[Diagram]
White idea instead of 3-3 point - leaving black+circle inefficient  

[Diagram]
What now?  
[Diagram]
White has no base  

If W4 at B5, then Black connects at W6. White is running with no base. Better to probe at B2 or a without the white+circle/B1 exchange.

[Diagram]
 

Is black+circle performing any useful function? The triangle is empty. W has 'c' to look forward to later as well. This is an inverted move order for B3 @ B5 to start.

[Diagram]
Or, stay connected and escape  

black+circle still feels awkwardly placed here. Defect at 'a' prevents B from attacking W4.


[Diagram]
Black to move.  

Question has been raised: what about probing at a or b before the 3-3 invasion? How does that play out?


[Diagram]
Black to move.  

Herman: The standard idea after B1 would probably be W2, after which there are several options.

[Diagram]
Black to move.  

Herman: With moves like this, black can reduce white to only one (potential) eye in the corner, but white has escaped, so black should have a clear plan to continue the attack.

[Diagram]
Black to move.  

Herman: blocking on this side allows life, because W6 forces B7. Black should of course keep B5 in reserve.

[Diagram]
 

-- For completion's sake, another path to life.


-- B3 and B5 look slack to allow unconditional life.

[Diagram]
W dead?  
[Diagram]
W dead?  

Herman: White can answer B3 with W4. B5 is required, otherwise White will play there. The W6 makes life, because a is still sente for white.

-- thanks for this, I missed that obvious move.

[Diagram]
Ko for life  
[Diagram]
W crawls ; 11@a, 12@b, 13@3  

[Diagram]
Black to move.  

Herman: B1 is a vital point, but the exchange of W4 for B5 allows life again. (The atari at a is pointless, black will sacrifice and squeeze for oshitsubushi.)


BQM 526 last edited by Dieter on January 13, 2012 - 17:20
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