Kyu Exercise 8 / attempts

Sub-page of KyuExercise8

KarlKnechtel: Ooo, some complexity here. Looking more like an actual game situation than tsumego usually do to me.

[Diagram]
Easy targets  

Black can obviously capture the white+circle stones. Let's see what happens if he tries to go for the big kill. First, he will have to prevent White from connecting to the outside:

[Diagram]
Trying for the big kill - divide and conquer  

This is the way to do it - Black forms a bamboo joint so that c and d are miai to keep his stones connected, while a and b are miai to cut - we can worry about them later. Other plays won't do it - B1 at a, b or c will be answered by W2 at d, letting White connect via capturing black+circle, and B1 at d is answered by W2 at b, leaving B1 and a as miai to connect.

[Diagram]
White responds...  

Now, White takes advantage of sente to win the capturing race at the bottom, using the technique from an earlier problem. Otherwise, B3 at a and it's all over for White. The B3-W4 exchange is sente for Black, because of the threat to connect to the stones inside, and reduces White's eyespace.

HolIgor: B3 is bad here.

[Diagram]
Time for the capture  

White captures because there's nothing else useful to do locally; and if she plays tenuki, B7 at a forces the capture and leaves one fewer liberty.

[Diagram]
Can Black kill?  

B7 appears necessary - with any other move, W8 at B7 produces the requisite two eyes (three eyes, actually). Let's check White's responses:

[Diagram]
White tries to make eyes  

This dies in gote.

[Diagram]
White tries to make eyes  

Same with this, I'm pretty sure.

[Diagram]
White tries to make eyes  

No good.

[Diagram]
White tries to make eyes  

It looked promising, but fails.

[Diagram]
White tries to make eyes  

That's it. Even if the circled liberty had been filled, Black can't atari with B9 because of shortage of liberties.



So Black's grand plans are bound to fail, and he should just take the two stones on the side while he can (White doesn't get eyes at the bottom, but connects and escapes successfully).

Note: If white+circle had been Black originally (so that White would capture it), then White would have to be careful to capture right away at move W6. Otherwise, the marked space is no longer a liberty; and B9 (which is now playable; the shortage of liberties is gone without white+circle) is killing. What a hamete that would be - White doesn't appear to be threatened, so she assumes sente and plays tenuki; but it comes back to haunt her after she is forced to capture six stones and still can't make life or connect! (Or does White have other options without white+circle being in place? I'm not sure...)


Dieter: Karl, you're close in the diagram "White responds ...". As a shodan it took me a while before the rabbit bit the bamboo #:7 . Nice problem, unkx80.

"Close"? What did I miss? :/

unkx80: Thanks Dieter. =)

Hint: It is possible to almost fill the white group into a particular kind of big eye.

KarlKnechtel: Hmmm... Ok, how about this:

[Diagram]
Don't bite!  

Black can now play B3 because of not 'biting the bamboo'. It threatens to capture, so White captures...

[Diagram]
Rabbitty six  

Black makes the nakade inside a "rabbitty six" (so now I get all of Dieter's pun). Now a and b are miai to prevent an attempt by White to divide the space.

Mental note: For 'killing' tsumego, don't put a high priority on reducing eye space if you're trying to cooperate with inside stones!


[Diagram]
Optimised solution?  

Black plays atari with B3, White has no choice but to capture at W4, Black plays atari with B5. Whether White chooses to block at W3 or not her group is dead before she can kill the black group.

[Diagram]
Optimised solution? No!  

unkx80: White can play at W6 and give up one stone. When B7 captures the stone, W8 captures five black stones.

[Diagram]
Optimised solution? No!  

The end result after capturing: White lives. The points a and b are miai.


Kyu Exercise 8 / attempts last edited by ThorAvaTahr on December 24, 2011 - 09:48
RecentChanges · StartingPoints · About
Edit page ·Search · Related · Page info · Latest diff
[Welcome to Sensei's Library!]
RecentChanges
StartingPoints
About
RandomPage
Search position
Page history
Latest page diff
Partner sites:
Go Teaching Ladder
Goproblems.com
Login / Prefs
Tools
Sensei's Library