Source: 
Problem diagram.
Black's response to White's marked cut?
Finish the Opening, James Kerwin 1p
Solution follows
(or click here to download SGF)
Correct.
In the sequences that follow after Black 1,
White cannot break through Black's overwhelming outside wall.
White can try to escape with 2, but through 15,
Black has a net to catch the White stones.
This position is typical of what happens when White prematurely
invades with the marked stone, as described in last week's problem.
White variation.
The best that White can do is to play at 2.
Through 4, White captures a stone, but is sure to lose this game.
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