Two-space Extension - Unobvious Answers

  Difficulty: Advanced   Keywords: Shape, Tactics
First, the obvious answer  

The great virtue of the two-space extension is that it is difficult to cut through. When White plays W1, B2 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 B2 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 W1 is an overplay.

One should bear in mind that B2 as shown in this diagram is in most cases honte: the other plays aren't for general use.

The bulge point  

White's follow-up here is W3, 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.

White can force  

After that White has a chance to play some kikashi, with W1 and W3, and then perhaps a or b. Black has made a thinner shape and White's pay-off is this chance to complicate matters.

The diagonal play  

The unobvious play B1 here is an interesting example of shape, and seems only to be played in the presence of the white+square stone.

Now if W2 the position becomes tense. Black can try B3. White a, Black b came next in a recent Korean game: Black has cut in good shape.


This is better for White, when the white stones on the right were previously weak.

Inviting a fight  

Finally, B2 here is suitable when Black wishes to involve White in a fight. Up to W7 is a predictable result; White must now find a way out, or play more lightly here.

-- Charles Matthews

Bill: I have added B8, which looks like honte to me.
Charles Agreed, but then White at a escapes. When Black is strong locally - the cue for B2 - Black may connect otherwise on the left to force White to crawl out with b.

Bill: In 21st Century Go[1] vol. 1, Go Seigen make the following recommendations:

Go Seigen's recommendation (I)  

B3 takes the high ground, giving Black good balance.

Go Seigen's recommendation (II)  

B3 connects underneath. B5 could also be at a. This is also playable.


[1] 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

Two-space Extension - Unobvious Answers last edited by PJTraill on February 9, 2019 - 00:52
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