Problem diagram.
Black's response to White's marked stone?

Source:
American Go Journal, Vol. 20, No. 2, 1985, pp. 16-17
"Ten Commandments of Go"

Solution follows    (or click here to download SGF)

Failure.
White's corner invasion was a big overplay, and violates Commandment 1: Greed doesn't win. Black answers incorrectly by blocking the right side at 1, which is too concerned about the corner. With 2, White can hane to begin to form a base on the bottom in sente.

Correct.
Black should play the powerful descent at the bottom with 1. With 2 thru 10, White can make life in the corner. But White ends in gote. Next, developing toward the center with A or B puts Black on the way to an overwhelming win.

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