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BambooJoint

 

Bamboo Joint Example 1
    Keywords: Shape

[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 exerts 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 cannot 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 longer any ladder question 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 White 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, [table 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 Black 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


JamesA: A quick comment - I think the extra efficiency of Bill's version is demonstrated by the fact that after Black 2, Black has the option of playing at a, for instance. If Dieter's variation is played, Black can't do this.


[Diagram]
Diag.: More efficient


[Diagram]
Diag.: Pushing battle


There's more to say. If the players are going to make it a pushing battle, Black 2 belongs as shown here. This shape gives White a peep at p. So it may be useful only in that one case. Charles Matthews




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