P7A77: I think I have it...
Hmm, looking at it now, is misplaced. White at a seems to kill. Difficult problem!
Shaydwyrm: P7A77's solution left black short one liberty, so in an attempt to preserve that liberty:
plays on the point of symmetry.
or a, taking away a liberty, is the best response I can find - the sequence from
can be played on whichever side white does not respond. Playing at
first allows black to avoid pushing out on both sides, which loses liberties.