RTG Problem 20 / Attempts

Sub-page of RTGProblem20


Critical point?  

Living is not so difficult. Can black do better?

unkx80: Unfortunately, this does not live. Think under the stones.

wait a minute. why doesn't this live? If white cuts 1 and 3 the snapback works. (black retains miai) Am I being dim?

unkx80: Sure the snapback works, but think further than the snapback itself. As the name "under the stones" imply, please consider what happens after the capture of the stones (in the sense the stones are physically removed from the board).

(Later) I actually forgot that I had this problem set as Snapback Problem 16. That should explain why.

Under the stones  

After black+circle has captured the White stones in a snapback, W1 prevents a second eye.

Black to play--this fails  

a and b miai for killing.

not convinced?  

Will this work, find it hard to read out the snapback

Bill: B5 dies. W6 fills at black+circle. No snapback. Ko.

MikeTerry: I can't see anything better than this for Black. White can try the same under the stones trick as in the first diagram, but then...

W tries to avoid Ko?  

B3 forces W4, and the extra white stone totally changes things. After Black throws in with B7 at B5 and the resulting snapback we get to the following position:

W to play  

Note the extra space at a. Now when White plays back under the stones at b...

double Ko  

Black lives with a double Ko. So White is unable to avoid fighting a Ko at some point in the sequence to kill.

Bill: Nice analysis, Mike. :-)

Simple life  

But even after W3 in the previous diagram Black is already alive, as a is protected.

Alive and well  

In fact, Black is even alive in this position, after white+circle. If W1 tries to take away Black's eye, B2 captures W1 because of damezumari.

MikeTerry: DOH! The perils of late night posting :)

RTG Problem 20 / Attempts last edited by on May 8, 2004 - 20:16
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