Good Empty Triangle

    Keywords: Shape

Table of contents Table of diagrams
Joseki
Related joseki
Mutual good shape
Black to play
Good empty triangle
Bad empty triangle
19x19 diagram
Black continuation

Efficiency is one aspect of shape. Late in the game, especially, it can be obviously correct to make an empty triangle and making an empty triangle can also be the vital point. A good empty triangle is an instance of what the Japanese call guzumi.

Example 1

[Diagram]

Joseki

B2 is the vital point, even though it is an empty triangle.

[Diagram]

Related joseki

B2 makes "good shape" but becomes overconcentrated.

unkx80: I don't think it's so much about overconcentration. I believe that it's got more to do with destroying White's eye shape.

Bill: Well, it is a question of emphasis, isn't it? Anyway, let's take away the BC stone.

[Diagram]

Mutual good shape

This is fine for both players, no? Black does not need an extra stone.


Example 2

[Diagram]

Black to play

This problem comes from the Tesuji Dictionary, by Segoe Kensaku and Go Seigen. They say that if you get this one right, you are 5 dan. (Of course, you have a big hint. ;-))

Solution


Example 3

[Diagram]

Good empty triangle

The sequence of W1 to W5 is one of the best ways of escaping with the lone white stone at the top. W5 makes the empty triangle and then White has a rather clear exit, while aiming for the cutting point at a (at the correct time).

[Diagram]

Bad empty triangle

W3 here would be a mistake. B4 plays at the vital point, destroying White's eye shape, and forcing W5 to connect with a bad empty triangle.

Bob McGuigan: Here's an example from one of my own games (I was Black) where Black responds to a White empty triangle move by making one too. White's empty triangle looks good but after Black's response ...

[Diagram]

19x19 diagram

B2 in response to W1 is good defense. W3 creates a cutting point in Black's shape. B4 takes a liberty from White and leaves a lot of aji against White's group.


Example 4

[Diagram]

Black continuation



This is a copy of the living page "Good Empty Triangle" at Sensei's Library.
(OC) 2005 the Authors, published under the OpenContent License V1.0.
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