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35PointJosekis
AttachCrosscut
34PointLowApproach
44PointLowApproach
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Attach-crosscut corner patterns
  Difficulty: Advanced   Keywords: Joseki, Strategy

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

[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 BC: 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 BC, why not try to make Black overconcentrated here? W3 is a sacrifice to do that.

[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 BC. Sequences like this have been tried by top Korean pros.


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]
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 WC now doesn't seem a good idea.


[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



This is a copy of the living page "Attach-crosscut corner patterns" at Sensei's Library.
(OC) 2004 the Authors, published under the OpenContent License V1.0.