Problem diagram.
White's response to the marked play?

Source:
American Go Journal, Vol. 22, No. 1, p. 29
Keshi and Uchikomi, Kaoru Iwamoto 9 dan

Solution follows    (or click here to download SGF)

Failure.
White 1 is horrible. With 2, Black has now gained on both sides of the weak baseless White group.

Correct.
White should counter attack at 1. After Black defends with 2, White then follows up with 3, which is the standard play in this type of position. White 5 creates good shape. Black's previous steady play at 4 allows Black 6 to take the initiative to menace the White group above. Note though, that if necessary, White can play A to live easily on the inside.

Black variation.
With 4, Black can play more aggressively. White 7 creates good shape to complete the initial invasion phase. Later, A is again a key point for both sides.

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