Source: 
Problem diagram.
White plays.
Finish the Opening, James Kerwin 1p
Solution follows
(or click here to download SGF)
Failure.
Even though White is an amateur 2 dan, his decision to invade
at 1 is a common mistake, viz., starting the middle game before
the opening if finished.
When Black caps at 2, the game is already over!
White can live in the lower right, but only in gote, with Black
pressing from the outside. Black will then attack the top right
group with A. Both White groups will live, but only with a tiny
amount of territory. More importantly, Black will have an outside
wall stretching all the way across the board. Black has a sure win.
Correct.
The correct sequence starts with the force at 1.
Black must respond with 2 or risk major damage to the lower right corner.
White can then take the biggest opening point at 3.
White has struck a much better balance between reducing Black's territory
and building his own at the same time. So opening moves have double value.
Invasions only have a single value, i.e., you deny your opponent territory,
but you get nothing for yourself.
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