BQM 523

    Keywords: Question
Why does W4 work?  

A question that troubled me yesterday evening. Why does W4 work? (This is a move I will never find, if I did not learn it before I see this situation the first time.)

Why does W4 work? - Assume ladder works for Black  

Now Black can't resist White with a double hane - even if the ladder is good for black - but has to give a huge corner.

Bottom line: Can one play the 3-4 invasion under a 5-4 stone without knowing this line at all?

Black alternative  

fractic: If the ladders favor Black why doesn't he play like this in the first place? I thought that part of W4 was that black can't capture the cutting stone.

tapir: The ladders are not identical. So one may work, the other not - I guess the most important issue here is to know why the ladder does not matter in the line given above. But this pushing against the black stones is so counterintuitive (at least to me) that I would have no chance to see it without earlier exposure.

Ishida's Dictionary of Basic Joseki volume 3 page 42. The diagram above, labeled Black alternative is Ishida diagram 110. Ishida says However, the ladder with B7 (B3 here) cannot be favorable for Black or White would not attach in the first place, so this pattern is shown just for reference.

W4 in the original diagram, Why does W4 work? is similar to a line of play on page 44 of Ishida

13th Meijin League. White Ishida; Black Otake  

The ladder was favorable, so White attached at white+circle. Black answered.... Black 1 is a fairly unusual move -- one cannot say whether it or the extension is better. White 9 and Black 10 are natural and the ensuing sequence is probably forced.

13th Meijin League. White Ishida; Black Otake  

If White does not play 4 and 6, the adverse potential remaining in the corner is unsettling.

The main line  

BQM 523 last edited by Dieter on January 13, 2012 - 17:20
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