4-5 point 4-3 approach outside contact

  Difficulty: Intermediate   Keywords: Joseki
[Diagram]
Outside contact  

B1 is not so often seen now in pro play, because it relies in one major variation on a ladder. Nowadays, joseki involving ladders may be experiencing a decrease in popularity. See Ladder strategy / Discussion.

Deviations from the sequence up to W4 are very rare.[1] Tenuki with W2 is also very rare: see 4-5 point 4-3 approach outside contact, tenuki.

After W4, it is expected Black will cut at a or b. White will capture the cutting stone and Black takes either territory or influence. W2 at b also.

[Diagram]
Variation  

On a few occasions in pro games, W1 is played. This continuation is typical: White's position is low, and Black has influence on the left side. By playing this way White does limit Black's choice.

[Diagram]
Outside contact main line  

This is by far the most common variation, with Black taking the corner. Since white+square does retain some aji, follow-up plays here require careful thought.

White a is often played immediately, since White does not want to allow Black the severe play at b.

[Diagram]
Variation - potential ko  

On the other hand Black can still play for influence here, with B1 instead of the cut at a (previous diagram). After W4 it looks like a ko: this is unlikely to be fought out (though it was in a game Rui Naiwei-Pak Chi-eun(B) 2001-02-12).

[Diagram]
Continuation  

Assume W2, B3 elsewhere as ko threat and reply, and W4 recaptures at white+square. Then B5 is acceptable to Black in most cases: W6 seems required locally, and this exchange gains Black influence.

[Diagram]
Outside contact ladder line  

B1 and B3 to capture white+circle in a ladder aren't seen so much, now. After that Black's ladder capture at b, and attempt to force White at a, are important follow-up plays.



See further discussion at Capture the cutting stones in joseki 1.


[1] W2 at B3 is known (Hashimoto Utaro) but in a context where B1 related to a ladder question. W2 at the square-marked point, playing into bad shape (see six kyu noseki) has been played by Sakata. B3 at W4 is known in a game of Go Seigen, and as played by Cho Tae-hyeon.


[Diagram]
variation  

But then, how would you answer to Cho Tae-hyeon's variation? I've thought about this a lot and haven't come up with any good sequence for white.

xela: The key point is a, by analogy with a well-known joseki. Black will reply at b, then white can play c to make life in the corner. White can also force at d before playing c, expecting black e, but black can reply at f instead to make things more interesting :-)

(Why is c the correct shape to make life? There must be some interesting variations behind that choice, but I don't know, I'm just copying what I see in pro games... Perhaps white x instead allows black to seal white in with sente?)


Minue: A brief answer to xela's Question.

Which one is better for black of 2 follow ups below?

The answer is obviously the second one. So, white chooses the first follow up, so it's joseki sequence.

[Diagram]
Follow up 1)  
[Diagram]
Follow up 2)  

Question follow-up: But according to this Six Kyu Noseki, black could set up a double-hane like this, if white plays as xela suggested:

[Diagram]
double hane  

And then there's no good continuation for white?


4-5 point 4-3 approach outside contact last edited by 50.23.115.116 on January 27, 2015 - 05:49
RecentChanges · StartingPoints · About
Edit page ·Search · Related · Page info · Latest diff
[Welcome to Sensei's Library!]
RecentChanges
StartingPoints
About
RandomPage
Search position
Page history
Latest page diff
Partner sites:
Go Teaching Ladder
Goproblems.com
Login / Prefs
Tools
Sensei's Library