: ( 507)
This is sente, but threatens in one direction only.
:
White now needs an additional move to frustrate Black's hopes of an additional point of territory in the centre, either immediately or at the end of the Semeai Variation that later starts with a move at . In our solution, there is no use for the resulting sente for Black, but sente does matter in the classic move sequences.
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:
If White does not play her additional move in the centre, Black establishes another point of territory () after White's mistake.
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If White has played correctly (), there are no further points in the centre.