Source:
Problem diagram.
Black plays: A, B, or C?
Go World #4, Nov-Dec 1977, p. 56
Solution follows
(or click here to download SGF)
Correct.
Black 1 is best. White's lower center right group is the weakest.
Through 5, Black builds up a center position while keeping up pressure
on the White center group. And all of Black's groups are strong.
Inferiror.
Black 1 is a big play, but lets White off the hook in the center.
White forces at 2 in sente first to settle the lower left group.
With 4, White can skip out to the center.
With 6, White advances even further into center. White now has no
unstable groups. In addition, Black has to worry about White attacking at A.
Too small.
Black 1 misses the global picture.
White 2 takes the crucial point.
(Note that trying to escape in the top right instead would have justified Black's first move.)
Now Black 3 must defend the right side.
Again, Black 5 must defend.
White's play at 6 exposes the weakness in Black's plan.
Defending with Black 7 looks unavoidable.
And White can take the last large point at 8.
White now dominates the center. Also, the marked stone takes much of
the value out of Black's right side. Lastly, White's aji in the upper
right, starting with A is something that Black has to worry about.
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