thanatos13: this is it, right?
kb: Doesn't work. Even without the stone, at a captures three stones.
unkx80: This appears to be one of those problems where the original problem poster has left SL a long time ago, yet nobody here is exactly sure of what solution to expect.
I suspect the intended solution is something along this line: the key is to force and so that can separate the White stones at the top.
togo: at seems to be enough to defeat this plan.
togo: Aforementioned refutation with a continuation ( to at a to d).
togo: Maybe ko is the solution ( at a).
togo: Oh, well, forget it: White at b saves the white group (Also with eg. at and at ).
BCh Maybe this ? White is short of liberties so he can't kill the black stones.
BCh I don't see how to avoid a ko after white 6, but that's a ko that black takes first. is not a ko as white can force a, b after