We shall start off from instead...
The solution is presented below.
Discussions welcome.
--unkx80
BillSpight: is tesuji, but
makes a and b miai for a second eye. This is a diagram in the Sekiyama book to show that
is a mistake.
However, it looks like the vulgar play works.
If is played at
instead, then White takes the stone at
and it becomes a ko. (
at
produces another ko; I've added it as "Variation 1 (c)" below. Dieter)
After the placement at , a and b are miai. White is dead.
If as marked, then
at a. It is a ko.
( at
)
With , White dies with a farmer's hat eye shape.
This variation reverts to Variation 1.
Finally, White's resistance at is useless.
descends, and a and b are now miai.
--unkx80