Empty triangle
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This shape is an empty triangle, empty referring to the unoccupied point at . Typically, the empty triangle is bad, being inefficient and prone to shortage of liberties. Empty triangle is also sometimes called the devil's shape (onigatachi), because it brings to mind the long nose of one kind of Japanese demon.
In contrast, the full triangle, with a White stone at , is good shape.
On the other hand, adding a Black stone at creates a dumpling shape, which is even more inefficient.
Beginners: Here's a page to help you spot the empty triangle and avoid it.
Additional Black stones, such as the legs of a, or b or c, give this shape different efficiency and shortage-of-liberties characteristics, and as such it is no longer called an empty triangle, although it may still be so-called stupid shape (gukei).
The presence of the stones in place mean that this is not an empty triangle either, but rather a diamond or ponnuki with an extra stone at
, a common shape.
In some situations, a good empty triangle can exist as the best available local shape. The Japanese term guzumi can refer to such situations.
Guo Juan's AudioGoLessons has three audiolectures on empty triangles.
Empty triangle in popular culture
Empty Triangle is also the name of a Go comic strip.
Example
This first example, from professional play, offers a surprisingly large number of empty triangles.
brindis: some of these are not good examples; an eye is not counted as an empty triangle. In fact, there is only one thing worst than an empty triangle: filling it with a stone of the same color :-) But if you are forced to convert the inner point of an empty triangle in an eye, just thank your opponent.
The capture of leaves an empty triangle -- in fact, two empty triangles,-- around the vacated point. Since it is a capture and threatens another capture, it may be a good play, but it does form empty triangles.
Next, plays atari, catching the
stones in a connect and die. This illustrates the liberty problem with the empty triangle (too few liberties per stone played).
takes
, forming another empty triangle, and
takes the
stones, incidentally forming one more empty triangle.
A little later cuts, but forms another empty triangle.
forces
, which forms another empty triangle.
is atari, but forms yet another empty triangle.
connects, but forms another empty triangle. Now
forces
, taking advantage of the liberty problem.
forces
, which forms yet another empty triangle. After
secures the corner,
ensures the capture of the
stones, taking advantage of the liberty problem. Finally,
makes an important connection, but forms an empty triangle in the process.
This comedy of empty triangles (11 in 24 moves!) illustrates some of the problems with empty triangles, as well as the professionals' willingness to put up with those problems if the circumstances warrant.
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