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Bamboo Joint
    Keywords: Go term

[Diagram]
Diag.: Bamboo Joint

The black shape (marked stones and 2) on the left is called a "Bamboo Joint".

The two black strings are connected and cannot be cut apart. The bamboo joint is often a better response to an approach move than a direct connection. In the diagram, after white approaches at 1, black 2 is much better than black 'a', which would create an empty triangle.

--MortenPahle



[Diagram]
Diag.: solid connection

Jonathan Cano: playing black 2 may be better (because it fills a white liberty) than B if black is racing to capture the white 1 group.

Frequently black has no hope of capturing white's stones so playing a move that keeps black connected (as 2 here does) but also helps black in other parts of the board is better.


[Diagram]
Diag.: Bamboo Joint

Here, black 2 keeps black just as connected as a play at A but exterts more influence in the direction of B than a play at A does.

Also notice that if white pushes at C black can block at D and white is unable to cut at E unless the ladder works in white's favor. If black 2 was at A and white exchanged C for D then white can cut at E even if the ladder is unfavorable.

Examined in this way it is obvious why black 2 is much stronger than black A when black can not seriously threaten white's top group.

--Jonathan Cano



[Diagram]
Diag.: Bamboo Joint

Black could also answer 1 at 2, so that after 3 he can block at 4, and there is even no ladder question anymore about white's play at B ! But it's a move that can be easily turned into an empty triangle.

(See also Bamboo Joint Is Bad Shape?)

The shape move is the bamboo joint, and I'd recommend against Black A in the majority of cases. It's an empty triangle for one thing, and yes it takes away a liberty from white, but it takes one away from Black too ! So as long as the fight is one that one can't count, there is no reason to play bad shape. If the Black group is an outside group, surrounding a white group which is involved in a semeai with another black group, that's the only occasion where Black A might be called for.

--Dieter Verhofstadt



[Diagram]
Diag.: Keima connection

After W 1, the bamboo joint fails to work with the marked Black stone. The keima connection is more efficient.

If White tries to cut,


[Diagram]
Diag.: Ladder

Black has a ladder.

-- Bill Spight


[Diagram]
Diag.: Keima connection

I suggest this move. It combines two nice shapes: 'marked + 2' and 'unmarked + 2' (see shape). Moreover, Black is connected regardless the ladder, and White has little forcing moves against this shape. White A for instance, is forcing against the keima connection proposed above but is not forcing here.

--Dieter Verhofstadt


[Diagram]
Diag.: White peeks

If White peeks at 1, here is one normal variation. White keeps sente, but Black builds influence. Also, White has peeked at a bamboo joint. ;-)

-- Bill Spight


[Diagram]
Diag.: White peeks

Still, the marked stone feels awkward. Wouldn't it be better at A ? In other words, I don't think that this diagram disproves my earlier assertion.

--Dieter Verhofstadt (not trying to drive anything home, just discussing to learn)

Sure, the marked stone would be better at 'a'. But the White stones 1 - 7 would be a lot better somewhere else, too. ;-)


[Diagram]
Diag.: K1

The fact that B 2 combines two nice shapes is a clue that it is inefficient. One nice shape should suffice, unless the group is under pressure. The marked stone is clearly not pulling its weight.


[Diagram]
Diag.: K2

Even here it is not necessary. Take it away and there is still a ladder.


[Diagram]
Diag.: No ladder

And even if the ladder does not work, it is easy to give up the marked stone.

So even the keima connection is a bit inefficient. But it at least makes use of the marked Black stone in diagram K2.

-- Bill Spight


[Diagram]
Diag.: No ladder

-- Dieter


[Diagram]
Diag.: No need

<hehe> My point. :-) The circled stone makes the squared stone unnecessary.

-- Bill



This is a copy of the living page "Bamboo Joint" at Sensei's Library.
(C) the Authors, published under the OpenContent License V1.0.