Sunday Problem #49

Published 9 May 2021 by antti (last edited 17 May 2021)

This is an original problem by me, based on a shape that occurred in a league game between Soeren and Lebertran. Subscribers of the 2021 April league can view the game here.

Black to play.

The problem
This problem is mainly about how to turn ‘a’ and ‘b’ into two eyes for Black. Normally, both of they are gote eyes, so Black could only get one eye in total – some magic is needed.
Note that ‘c’ is a red herring: there is no way for Black to form an eye there.
Failure (1)
For instance, if Black forms an eye with 1, White just plays 2. An attempt in the corner such as black 3 will just fail to white 4.
Failure (2)
Descending with black 1 here doesn’t work either, although it is a bit more promising. This time White plays 2, and responds to black 3 with 4. The white corner is alive, and Black cannot form two eyes.
Black has to start with the throw-in of 1. White has no choice but to capture with 2 if he wants to try to kill Black, but then Black forms an eye with 3. 4–6 naturally follow, and then Black throws in at 7 – now the best White can get against Black is a kō.

Comments (1)

antti wrote 1 month, 1 week ago:

Solution added.