Attach-crosscut corner patterns

  Difficulty: Advanced   Keywords: Joseki, Strategy

Table of contents Table of diagrams
Opening
Joseki
Play to overconcentrate
Joseki continuation
Joseki continuation
Cross-cut joseki
Cross-cut joseki - one line
White's reply at ''a''
White's reply at ''b''
Continuation
So ?
What?
Or?
Influence vs. profit
Influence vs. profit (ii)
Variation
Cross-cut joseki - another line
Cross-cut joseki - another line
Joseki?
Continuation
Continuation

As ideas in joseki, these applications of the attach-crosscut shape are marginal patterns but with some interesting concepts and tactics connected to them.

[1]

1. Strategic ideas

[Diagram]
Opening  

For example this is a normal modern opening (see preventing the formation of the Chinese opening).



[Diagram]
Joseki  

Black may well play out the common joseki given here in the right-hand corner. That leaves B5 giving indirect support to black+circle: White can't hope for a very good result playing on the lower side, because B5 is a low stone in a solid group.



[Diagram]
Play to overconcentrate  

Later, W1 and W3 are a theoretical way to play here. If a pincer isn't good, because of black+circle, why not try to make Black overconcentrated here? W3 is a sacrifice to do that.

Bill: As noted below, the sequence given has been tried by top Korean pros. However, a GoBase search gives 'a' as the most frequent local response for White, with 'b' - 'f' as other alternatives. Also, 'g' shows up more often than W3. And it is usual for both sides to tenuki. With a 6 space gap between the Black positions, it is not clear that Black becomes overconcentrated in this variation.



[Diagram]
Joseki continuation  

These are standard plays, with White adding one stone and sacrificing both. Clearly the timing W8 before W10 is correct to make the most of the sacrifice.



[Diagram]
Joseki continuation  

This finishes off the sequence - White probably makes a flanking extension to a big point on the left side now.



The judgement of this result has to be based on the overlap in influence between Black's group to the left - now unquestionably thick - and black+circle. Sequences like this have been tried by top Korean pros.


[2]

2. 4-4 point joseki

For the corresponding 4-4 point joseki, the strategic meaning is nearly the same.

[Diagram]
Cross-cut joseki  

Black will play B3 for a good reason, probably that White is already strong on the top side.

[Diagram]
Cross-cut joseki - one line  

In reply to W1, B2 is an old move of Go Seigen that has been seen often since 1990. Now White a or b.



[Diagram]
White's reply at a  

Suppose W1 to leave a cutting point in the corner, up to B10 is normal and White needs to add a stone: so that Black ends in sente. Assuming this result, Black ought only to start the joseki if White's strength now overlaps with the upper right.



[Diagram]
White's reply at b  

If W1 with the idea of giving Black an empty triangle, B2 is tesuji.



In fact this line occurred mostly in problem books rather than high-level games, until recently.

[Diagram]
Continuation  

The reason is that if W1 captures we get B2 and White can only get any sort of result here with W3 which is a massive ko fight.



Top pros have indeed got involved with this, though.

[Diagram]
So ?  

So what about the empty triangle? How will White continue? Like this?

[Diagram]
What?  

B4 at white+circle.

[Diagram]
Or?  




[Diagram]
Influence vs. profit  

B4 at black+circle.

[Diagram]
Influence vs. profit (ii)  



Bill: Suzuki and Kitani's Small Joseki Dictionary gives the variation in the above two diagrams, judging it as an even exchange.


[Diagram]
Variation  

If instead it's W1 here, Black plays B2 since the triangle is now filled.



White can look forward only to a small life here, and perhaps white+circle now doesn't seem a good idea.


unkx80: The following appears to be another joseki.

[Diagram]
Cross-cut joseki - another line  

This line is sometimes seen in amateur and professional play. If there are nearby White stones towards the right side, this line of play aims to make White overconcentrated.

[Diagram]
Cross-cut joseki - another line  

W1 and W3 (note their order) turns Black into a dumpling before capturing at W5. The W1 stone leaves some aji in the corner.


[3]

3. Complex variation for the 3-5 point

[Diagram]
Joseki?  

There is also this complex variation. It is not seen that often in pro play, though it does occur occasionally in high-level games.



The joseki dictionaries aren't a safe guide (that includes Ishida, 2nd edition in Japanese) since there it isn't at all clear that the main line given is from pro play.

[Diagram]
Continuation  



After B6 here, Yi Ch'ang-ho has played W7, rather than at a as in the 'book' (game 1991-06-0 against Yu Ch'ang-hyeok, colours reversed), and this was also seen earlier in Japan.

[Diagram]
Continuation  

These plays followed, as part of Black's plan to build up a central framework.

Charles Matthews


Attach-crosscut corner patterns last edited by Bill on May 16, 2008 - 03:14
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