Sunday Problem #41

Published 14 Mar 2021 by antti (last edited 21 Mar 2021)

This is an original tsumego by me. The solution sequence for this is not particularly outstanding, but as a tsumego this has value in that this position can easily result from a particular 3-3 invasion jōseki.

Black to play.

Black’s straightforward attack with 1–5 is correct, and the result is a two-step kō.
Black can also start by attaching at
a, after which white b and 1–5 follow; the result is practically the same.

Comments (3)

Tanukki wrote 1 month ago:

I don't know how white gets the 1-1 stone in any's unconditional life if that stone was at a better spot.
Anyway, black R18, white Q18, black T18 makes ko to kill.

antti wrote 1 month ago:

To be exact, I didn’t mean that this shape is part of a jōseki sequence, but that a particular jōseki can reasonably often develop into this shape.

First we have the usual q16-r17-r16-q17-p17-p18-o17-o18-n17-n18-m17 corner invasion joseki. Later, because of some fight on the right side, black plays s17-s18-s15 to get extra stones on the right side; white forces t17-s16. Later, black plays the t18 throw-in because it’s sente; white hangs in tough with t19. Later still, black plays m18 and white doesn’t answer; then black plays t16 and white plays n19, and we have the problem shape.

Your solution sequence is correct, although technically it’s a two-step kō to kill.

antti wrote 3 weeks, 4 days ago:

Solution added.