Sunday Problem #32

Published 10 Jan 2021 by antti (last edited 17 Jan 2021)

This is an original problem I thought up two days ago. The shape is closely linked to Sunday Problem #31, but this problem highlights an aspect of the base problem that people more rarely think about.

Black to play.

Solution
Solution (1)
Black 1 is the correct starting move – even though at first glance it appears to make a dying J+1 shape. Following . . .
9 at 2
Solution (2)
White 2 and 4 are the classic combination to try to force Black into one eye. However, because of the black group’s outer liberties, Black can fight back with 5 and 7. After black connects with 9, the group cannot be killed.
Solution (3)
Black does not actually even need to respond to white 10, but these two diagrams show why Black is unconditionally alive.
Solution (4)
Finally black 15 and 17 set up an oshi-tsubushi, ensuring two eyes in the corner without having to fight a kō.

Comments (1)


antti wrote 10 months, 3 weeks ago:

Solution added.