Here White has a choice of parallel ladders.
Because breaks just one of them, White must be careful.
and
are the correct way.[1] Now Black's stones can't escape.
here is a mistake, from the point of view of capturing Black.
Later on in the ladder makes it impossible for White to continue.
Moving closer along the diagonal does change things, White might then want to play
,
and
here instead: a driving tesuji.[2] It all depends on the direction of play whether capturing Black on the left, or blighting
on the right, is bigger.
[2]
Calling either ladder correct is questionable, when the net at also captures Black's stones. If Black tries to escape, say with
, White can play atari. Note that the net works even if there is a black stone on the circled point.
-- Bill
Charles OK then, perhaps the final version of the lesson needs an extra stone, such as .
It is painfully easy to miss a knight's move net like in a real game (
at a fails much more obviously). Up to
Black looks to be well set to escape.
Urgh - the paper is too small to contain the rest of the sequence ... Black at a is about to be strong.
A better version of the original diagram would therefore deprive of further liberties.