After , White can catch Black in a net with . and can be exchanged without changing the result.
Brent: Then what? How does Black continue after ?
Because will force a protective move, anyway. Even if Black can play - with sente, Black will have to play .
OTOH, if Black plays at a, he threatens , saving .
It is a very close call. Depending on the rest of the board, could be better.
Gronk: I was surprised not to see discussion of the possibility of ko.
Gronk: Therefore, at is safer.