Solution to Problem on BobMcGuigan
Black to play, White dies.
After , Black gets a nakade with a.
jvt: Beautiful problem. I wonder if White can get a ko like this?
at a. This was suggested by Tsukamoto Chiaki on r.g.g. It is similar to variation 1b above.
jvt: After in diag. K1a, White plays , then Black can only play the ko at a. No other move will work.
DaveSigaty: This position comes from game 3 of the 8th Meijin Final between Cho and Otake (Black), 1983-09-28. The black stones in the upper left match the problem but the surrounding stones are different. Cho never tried to kill Black. Did he miss a chance or did he correctly read out that Black lives?
BobMcGuigan: This game has a published commentary by Hane Yasumasa 9p in Go World issue number 34. Hane points out that Black can live unconditionally but only in a way that helps White on the top. Hane felt that Cho missed an opportunity. Without quoting the commentary in detail, Black has to respond to a white attack at either by a hane at the circle point, which allows White to play at the point marked with a square in sente, or else Black could answer the white attack at in the next diagram.
After , Black a, White b, etc. through Black e follow and White has succeeded in playing d in sente; which, according to Hane, will be important later in the game.
BobMcGuigan: I think it is interesting to see how the problem position arose. It started with a very common joseki sequence, as in this diagram, and the position at issue in the Cho-Otake game resulted from natural middle game moves around this shape.
I won't give the details (and the players were then strong amateurs), but the interest here became how to handle this in the endgame. Black could still run out at a; meaning that the attack with White at b wasn't going to kill. In the end White did take profit with an attack and send Black out into the centre.
BobMcGuigan: It is problem number 162 from the book "Shuuko Sousaku Tsumego Kessaku Shuu" by Fujisawa Shuko, published by the Nihon Ki-in in Japan, 1980. The title means "A Collection of Original Tsumego Masterpieces by Shuuko". I can't resist mentioning that the word kessaku (masterpiece in the title) could, in other contexts, mean "blunder".