The empty triangle is bad

  Difficulty: Beginner   Keywords: Shape, Proverb

Table of contents Table of diagrams
Empty triangle
Empty triangle vs straight line
Efficiency (1)
Efficiency (2)
The full triangle
How does an E.T. arise?
How does an E.T. arise?
Park Junghwan (B) - Qiu Jun (W), Fujitsu 2011
Moves 72 to 81
Not so good, either

Abstract form

[Diagram]
Empty triangle  

The black group to the left is an empty triangle as there is no stone at a. The white group is not an empty triangle (it is a full triangle), as there's a single black stone next to it.

Why is an empty triangle so bad?

[Diagram]
Empty triangle vs straight line  

First of all, the empty triangle doesn't maximize its liberties. It has 7 liberties in isolation, wheras the straight three have 8 liberties. Both make a strong connection. The loss of a liberty without any kind of gain is unacceptable. There are many, frequently occurring positions in real games, where this one liberty is vital.[1]

[Diagram]
Efficiency (1)  

Secondly, two stones in a diagonal are connected, in the sense that they cannot be separated in one move, but they can be sacrificed if desired. Now the empty triangle is connected too, strongly, has a little bit more influence but must be sacrificed as a whole if needed. The one extra stone adds close to no value. It is a wasted stone.

[Diagram]
Efficiency (2)  

Also, if Black wants to develop to the right, then play the marked stone black+circle instead. White cannot cut this formation without help from surrounding stones. Black's stones are securely connected. Closer to the side, farther extensions are virtually connected. This development is much more efficient than the empty triangle.

[Diagram]
The full triangle  

In contrast, the full triangle is very strong and efficient. In the upper position, Black can be cut. So, B1 below fulfills a very important function: it connects two stones. By doing so, the white stone becomes very weak. The investment is 3-1, whereas in the empty triangle it is 3-0. Black's moves all have purpose.



Empty triangles in actual play

[Diagram]
How does an E.T. arise?  

In this opposing jump position, White can lull himself into thinking the peep serves the double purpose of connecting and threatening to cut. Then, W3 jumps out.

[Diagram]
How does an E.T. arise?  

However, he puts himself in a bad position. Black's straight three are strong, while White's zigzag three are weak. Black B4 threatens to cut at W5, and White has to connect.

Now he has connected, but W1 forms two empty triangles and serves no purpose whatsoever, while Black's peep B4 is on the outside and provides support to the attacking stone black+circle.

Instead of exchanging W1-B2 White should just jump out to W3. If black later plays B4 then W5 is needed. But W5 right away is way too slow. The one point jump is hard to cut anyway. See don't try to cut the one point jump.



Empty triangles in professional play

[Diagram]
Park Junghwan (B) - Qiu Jun (W), Fujitsu 2011  

W9 is the only way to save the all important cutting stones. According to An Younggil in his [ext] commentary on gogameguru, pros don't care as much about good shape these days. However, a few moves earlier he also commented that W1 was an overplay .

[Diagram]
Moves 72 to 81  

Probably White had it all planned out until Black came up with this B10, which was a brilliant move according to the commentary, so that indeed White willingly anticipated the empty triangle in the previous diagram. Nevertheless, the shortage of liberties of the empty triangle created this opportunity for Black.


See also


[1]

[Diagram]
Not so good, either  

This comparison does not mean that this shape is good. In fact, you will not find this shape, with no opposing stone on any of these neighboring empty points, in a professional game. So any shape discussion is most relevant with actual game positions.


The empty triangle is bad last edited by 68.119.140.144 on December 3, 2013 - 22:02
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