Source: 
Problem diagram.
Black plays.
"Getting the Most Out of the Opening", Ohira Shuzo 9p
Solution follows
(or click here to download SGF)
Correct.
Black is eager to extend to the splendid point at 1.
If White defends the lower side with 2 and 4, Black 5
forms an ideal position in the upper right.
White variation.
White can try the standard move at 4 to erase Black's potential,
but Black correctly defends the upper side with 5. White 10
finishes a standard reducing sequence, but Black seizes the
initiative with 11 to build up power in the center, and White
cannot easily settle his upper right group.
White variation.
Earlier, White might think that extending at 2 is big, but 3
extends Black's sphere of influence. White can try the
shoulder hit at 4 to limit Black's influence, but through the
rest of this sequence, White has a group of weak floating stones
and a difficult position to play.
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