Attach-extend on the side, tenuki

  Difficulty: Advanced   Keywords: MiddleGame, Joseki
Attach-extend somewhere on the side  

These plays in the attach-extend pattern often occur displaced along the side: it might be as a middlegame joseki, but there are also a number of corner joseki that show this pattern, in which black+circle isn't the initial corner stone.

Suppose White now plays tenuki. One case in which this is frequent is in double kakari joseki, when White wants to pay attention to the group on the other side of the corner.

In any case this is a situation for which there are a number of standard patterns.

Black's vital point for attack  

In this position B1 is considered the vital point for attack. It is not the only choice, since Black at a is also played. Black at b can be noted, since Appreciating Famous Games comments on it. It lacks severity. It has, however, been played by some very strong players.

What happens now depends to some extent on Black's shape (matters may be affected by black stones at the marked points that protect Black's cutting point weakness), and White's interest in coming out to the centre.

There is this way for White to try to live quickly (immediate life):

White butts  

After W1 here and B2, it is hard for Black to prevent White living on the side. It is true that Black can stubbornly play B2 at W3; but then White has an easy exit to the centre.

White slides  

An alternative is W1 here, which low but light. It is more like sabaki since Black can aim now to capture stones but finds it harder to attack all-out.

White's way out?  

In the majority of cases seen in pro games, we get W1-W3 played. Evidently White has acquired an empty triangle; and a good question is, 'why'?

So, backed up by the 123 principle, we can ask about simply coming out at W3. This also is a defective shape, though, according to compromised diagonal. You can say that W3 immediately does nothing to prevent black+circle seeming well-placed.

This isn't a simple question. There may be three factors operating:

  1. White's cutting point (square-marked), since W1 helps White resist cuts and some peeps;
  2. Black's cutting weakness (presence or not of a black stone at circle-marked points) in relation to liberties on the black+square stones;
  3. another group of White's to the left, affected by B2.

On a statistical basis, W1 is played much more frequently than not (this may not be a robust conclusion with slightly-changed searches).

Charles Matthews

Attach-extend on the side, tenuki last edited by on February 6, 2010 - 11:17
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