Two-space Extension - Unobvious Answers
The great virtue of the two-space extension is that it is difficult to cut through. When White plays , is a simple answer to prevent White separating Black's stones by playing there himself.
It is also the correct answer, in most circumstances. But there are occasions when one wants to play at a, b or c for reasons of local shape. It is even possible for Black to jump out at d in response; but that is when Black effectively claims that is an overplay.
One should bear in mind that as shown in this diagram is in most cases honte: the other plays aren't for general use.
White's follow-up here is , at what would be a bulge point for Black.
That would be one reason for Black to play this way. Now White at a would be odd, since if White wanted that result he would have started there.
The unobvious play here is an interesting example of shape, and seems only to be played in the presence of the stone.
Now if the position becomes tense. Black can try . White a, Black b came next in a recent Korean game: Black has cut in good shape.
Finally, here is suitable when Black wishes to involve White in a fight. Up to is a predictable result; White must now find a way out, or play more lightly here.
takes the high ground, giving Black good balance.
 PJT: Would that be A Way of Play for the 21st Century or one not listed in our article ‘Go Seigen’? Bill: It's a set of ten volumes in Japanese, written in the last years of Go Seigen's life. PJT: Thanks