Monkey Jump / Into High Position

How to stop the monkey jump?  

What's White's proper defense here?

Failure  

is wrong, as Black can push further into White's territory at . The marked squares are miai for Black, and White cannot cut off. Try it out!

Chris Hayashida: What about at ? Seems to me that Black can't live by taking the inside. Actually, I found my answer. If Black extends upward (down in the diagram) to , and White extends to a, then the black hane is hard to deal with. It would work if the ceiling were one line lower, though.

 

Timur? Doesn't it work in this way? at a, at b, at 6, at c

Correct response:  

It looks suprising, but works:

6 is crucial  

putting the two marked stones into atari is correct. If Black continues with , cuts it off.

variation  

What if Black does not play 7 like in the above diagram?

Then White still plays 8 like above and starts hunting the Black group, which by now has only one eye. It depends on the situation at the right side of the board which player will succeed.

Correct sequence  

Therefore, Black should play as follows:

In an actual game, Black should be satisfied by the exchange of the marked stones and keep the plays 1 through 10 in reserve. There is no need to play them out immediately.

Better Black reply  

The improved sequence is shown in 'Better Black reply', the diagram to the left. Black 1 in the above diagram is in this diagram, and White 6 in the above diagram is in this diagram. White 4 at (in this diagram) gives the same result. Black can still tenuki after White 2, but if Black plays next locally, it should be at , rather than .

Better White defence  

White 2 in the above diagram (titled 'Better Black reply') is also not optimal. White kosumi in response to the monkey jump as here is two points better for White. Black must play to avoid being cut off, and then is required. Apart from tenuki, black has three alternatives for (at 6, 7, or 9), each giving the same result. This is equal in value to the 'Correct sequence' above, and does not lose two points as does White 2 in 'Better Black reply' when Black plays in that diagram.

Relevant sequences are shown for a narrower but very similar position, at goproblems.com in problems 3762 and 4105, the creation of which led to this analysis.