Sunday Problem #17

Published 27 Sep 2020 by antti (last edited 4 Oct 2020)

This problem is also from Xuanxuan Qijing, or ‘The Gateway to All Marvels’. This problem is titled , or the ‘Fox-Catching Arrow’, apparently because the shape ‘looks like the arrow’s head’ – personally, however, I fail to see the resemblance.

While its name may be dubious, the problem itself is one of the most ingenious I have seen.

Black to play.

Instead of assuming that the problem is solved in the move order b-w-b-w- . . . we can try to identify the options for Black’s first move by assuming order w-b-b-w- . . . instead, letting White claim what seems to be the strongest eye-making move.
That move is probably white 1 here. Now, the only reasonable combinations of two black moves that kill White are
a+b and b+c. Therefore, Black’s first move is either one of these three or at white 1.
Black 1 looks like a promising first move, but White has an unlikely good response at 2. Up to 6, the white group manages to form two eyes.
Black’s tesuji is to start with the throw-in of 1. White 7 in response to this doesn’t work, as then black 6 kills.
The most difficult white resistance is probably the connection of 2; in response to this, Black has to find the non-obvious killing combination of 3–5.

Comments (1)

antti wrote 7 months, 1 week ago:

Solution added.