Question about the previous statement: This would be the position as described above. Where is the ladder for black?
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. :-)