Sunday Problem #20

Published 18 Oct 2020 by antti (last edited 26 Oct 2020)

This is a whole-board endgame problem from Ōhashi Hirofumi 6p’s book, (Sōkai! Kachisuji-sagashi) or Refreshing! Searching for the winning play.

If the title sounds strange in English, it is because sōkai does not translate very well; ‘refreshing’ or ‘invigorating’ are technically correct translations, but Western go players would rarely use them for the feeling of relief one gets when finally solving a tricky problem. And, somehow, it seems like ‘relieving’ would hardly make for a good problem book title in the West.

No komi or captures, Black to play. What is the best outcome for both players?

Black’s diagonal attachment of 1 is certainly a tempting move, but if Black starts from capturing the white stones here, Black finds she cannot win the game. After white 6 and black 7, the game results in a draw. (With captures included, both players have 22 points.)
Black’s cut of 1 is an endgame tesuji. If White wants to save his lower-right corner group, he has to answer with 2 (or 4) after which Black can reduce the white corner territory in sente with 3 and 5. After Black ensures this sente profit, she can then go back to capture the left-side white chain with 7. This way, Black wins the game by two points (21 to 19).

Comments (1)

antti wrote 6 months, 2 weeks ago:

Solution added.

My wife came up with another interesting translation choice for ‘sōkai’: cathartic (as in catharsis-inducing). ‘Cathartic tsumego’ would not only sound totally out of place, but also allude to something very different (as in cathartic medicine), which almost makes me want to use it as a joke book title.