Getting out doesn't work.
Black is captured in a snap-back (at ).
must go down, as after the exchange of a for b, the ladder in the false solution (1) would work
is an important tesuji : if played immediately at
, Black plays at
himself, and White has only two liberties. Now
, etc. repeat the same manoeuvre on the right, and we get to
Now for the really tricky part (it is easier if White captures) : the incredible , breaking the symmetry at last !! And Black concludes with a double atari at b, on the last point of symmetry :-)