Problem diagram.
White plays to reduce the upper side.

Source:
American Go Journal, Vol. 19, No. 1, 1985, pp. 28-31
Keshi and Uchikomi, Kaoru Iwamoto 9 dan

Solution follows    (or click here to download SGF)

Questionable.
(The given lines here are just a small sampling of lines of play to obtain a feel for the possibilities in this formation.)

If White tries to separate Black with 1 and 3, Black cuts with 4. White is going to be at a disadvantage in this fight.

Playable.
This line of play is not disadvantageous for Black, who has the corner for a base and can aim at A.

Bad.
White's stone lacks a base, in addition to not having an effect against Black's corner. This approach is not worthy of consideration for White.

Also playable.
Black 2 is one of many possible Black approaches. White 3 is flexible and generally acceptable. Black 4 is a good move that ropes off the corner and threatens to cut White. And White runs out with 7.

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