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Compromised diagonals and joseki 1
  Difficulty: Expert   Keywords: Opening, Joseki, Shape, Tactics

[Diagram]
Not joseki

Without a stone at one of the marked points, this is certainly not joseki.


[Diagram]
White's shape is better

If White is free to extend alone the upper side, then the exchange of BC and WC is in principle good for White. For one thing, playing BC at WC is joseki (3-4 point high approach outside contact).



[Diagram]
Chinese formation case

Given a black stone at BS (or at the marked point), the exchange B1/W2 is some improvement for Black: it possibly makes White heavier. Black now at a leaves White's stones floating.


[Diagram]
Ladder question

White's other natural resource is at W2 here. There is a ladder question involved. In pro games B1 may only be played when the ladder is good for Black: for example if White invades late and Black has some central influence.


[Diagram]
The ladder in question

If the ladder with W6 is bad for White, B1 here is possible after WC.


[Diagram]
A second ladder

A second ladder (Black at a) can occur if White rejects the chance to live small here after B2 (with W3 at W4). This position comes from an Oteai game Yoda Norimoto-Komatsu Hideki (B) 1983-06-29.

Charles Matthews



BobMcGuigan I don't think I'd want to play B1 in the first diagram above without some support to the right or, perhaps in a Chinese Opening type of situation, but I wondered how bad this move could be even if the ladders favor white.

For example, if things went as in the next diagram, it is clearly a bad result for Black since the marked stone is in the wrong place (it should be at a or b).

[Diagram]
Bad for Black



But what about this?

[Diagram]
More or less equal?

Andre Engels: I assume this is more or less equal, given that B2-W1-BC is a joseki, (although both a and b are clearly more common than BC). The joseki is discussed in 3-4 point high approach, double contact, wall





This is a copy of the living page "Compromised diagonals and joseki 1" at Sensei's Library.
(OC) 2003 the Authors, published under the OpenContent License V1.0.