cross-cut, diagonal away

  Difficulty: Advanced   Keywords: Shape
[Diagram]
Not 'correct' shape  



After a cross-cut in the centre of the board, W1 isn't a recognised good shape. One can give some reasons.



Supposing Black simply answers with black+circle. Then this is similar to the position in diagonal play reference positions?: White is at some disadvantage for influence. You could also say that black+circle threatens a good play at a.

[Diagram]
Different order  



With this order of moves W3 may also appear a little unreasonable.

[Diagram]
'Wrong' way to cut  



The same position arises here, though with Black to play. The 'correct' way to cut here is with W1 at B2 (strike at the waist of the knight's move).

Tapir: I disagree. 1 and 2 are both the "waist" of the keima - afaik. However, if 1 at 2, 2 at 1, 3 cuts at the point left to 1, than 4 can capture the cutting stone in a ladder. It may be bad shape, but here without any other stones, it is not the wrong cut, but the only one.


For all these reasons this is a relatively rare shape.

An example can be see at Attach-crosscut corner patterns, in the 4-4 point case.

Another is in this difficult joseki:

[Diagram]
Joseki  

This was played by Shinohara Masami against Go Seigen in 1935; it is hard to know how current B4 is.

Charles Matthews

[Diagram]
B4 explained  

This counter-example to the diagonal away move being a bad move has a reason. The main reason the diagonal move is bad is because on an open board after W5, the two black stones have bad shape, with a play at a a strong reason. However here a lies on the first line and so isn't a threat at all. Also, with a white stone bearing down, it is imperative that black can extend down along the side and for that reason B4 must be preferred to b.


cross-cut, diagonal away last edited by 1.120.197.187 on February 18, 2014 - 12:32
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