Problem diagram.
White plays.

Source:
Blueprint 361
Miyamoto Naoki
Go World #1, May-June 1977, p. 51

Solution follows    (or click here to download SGF)

Correct.
Pushing at 1 is the key point! Black can try to build up the bottom with 2. But Black cannot omit responding with 6. And Black must also respond to White's peep at 7. But White has room to invade the bottom with 9. If Black blocks White's escape route with 10, White easily makes life along the bottom edge with 11.

White making a strong shape at the top, and then taking advantage of the weakness of Black's center group and thinness of Black's lower side in this way, is a high-level strategy.

2nd best
The pincer of White 1 is the 2nd best move on the board, but not the best. Given the previous diagram, Black 2 ignores the pincer to take the key point. White can try 3, but through 12, Black's center group is largely safe, and Black has taken top territory from White. White's result is not good.

White variation.
White might instead try falling back to defend at 3. But comparing the result through Black 8 with the correct main line makes clear why this line is much worse.

A mistake.
White 1 is too defensive. Black 2 again takes the key point. White cannot seal off the top area with 3. Black 12 lays waste to White's hopes at the top. White has no hope of capturing Black. White's 1st move in this diagram has been for nothing.

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