voltrevo: (Orientation=top-right) After S19 and white plays P19, why does black need to play again? The obvious move is to atari at O18 which is the accepted answer, but what does this achieve? Other moves like M18 are not accepted, but I don't see the issue.
caranthir: Without O18 ate, the defender can play S18 or T19. After that O18 is too late, since the defender will capture and get two eyes.
Without O18 ate, the defender can play S18 or T19. After that O18 is too late, since the defender will capture and get two eyes.