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