Sunday Problem #21

Published 25 Oct 2020 by antti (last edited 8 Nov 2020)
tags: sunday-problem

Since we got started on the topic of whole-board endgame problems with Sunday Problem #20, here is another one.

This problem is from another Japanese problem book with an untranslatable name: (Katsu-yose no zetsumyō na tejun) by Mitsunaga Junzō 6p. A rough English translation would be Exquisite game-winning move orders in the endgame – feel free to suggest a better one in the comments if you can think of one!

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

Solution
Failure
White 4 and black 5 are worth a swing of 8 and 7 points, respectively, meaning that there is little difference which player plays which. Therefore, it seems prudent to play on the left side instead.
However, the commonplace black 1 is not good enough. After all the endgame moves are divided out, up to 12, it turns out the game is a tie. Black could have done better.
Solution
The very non-obvious first-line atari of 1 is correct. After White connects with 2, Black cuts at 3, and White cannot prevent Black from entering the corner with 5–7. After this, the endgame quickly calms down, and Black ends up winning by one point.
White’s variation
It could make sense for White to respond to black 1 with 2 here, preventing Black from entering White’s corner territory. In that case, however, Black can force 3–4 before returning to play the larger endgame move of 5 on the right side. Finally, Black wins this game too by one point.

Comments (1)

antti wrote 3 years, 5 months ago:

Solution added.

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