Three-space extension
Path: DiagonalAttachmentPath
· Prev: · Next: DiagonalAttachmentAsInferiorShape
Difficulty: Beginner Keywords: Opening
![[Diagram]](../../diagrams/3/f916d4fa41864641eec2b9d44cb1c288.png) | Example: Three-space extension on the third line |
Compared with the two-space extension, the three-space extension has two advantages, which can be explained using go concepts, and one clear disadvantage.
![[Diagram]](../../diagrams/2/b7d82307d19aac70625030a8034d3893.png) | White can invade |
To start with the disadvantage. White can invade at here, and (unlike the case of the two-space extension) Black cannot force a connection by immediate means. What Black usually does is to jump out, for example at a, enlarging the scale of the struggle; or to play at b (possibly leading to a later sacrifice), to make the most of tactics locally. Therefore this length of extension isn't easily handled in all positions.
![[Diagram]](../../diagrams/43/06fb10f755b15f666d7cafa81536d83e.png) | Advantage 1: not over-concentrated |
One major reason to choose to play the three-space extension can be seen in this sequence. If White is about to play the diagonal attachment at , Black's marked stone ends up on an ideal point after the proper answer (see extension from a wall). One line closer is over-concentrated, that is, worse, from the point of view of good development.
![[Diagram]](../../diagrams/7/c43669cb76b4ef488647ce1c43eb8d00.png) | Advantage 2: light |
The second possible advantage is if Black is seeking to play lightly - stay out of trouble.[1] This type of sequence is appropriate if White is strong in the upper right, as here. In that case Black a, White b might be good for White, and Black is better allowing in return for .
![[Diagram]](../../diagrams/35/4fdda05ac1d992b9d2e7d7fa8f783974.png) | Variation |
Here Black can be quite happy with his development.
In some contexts completing the shape with Black at a (instead of jumping out at ) might be better.
Charles Matthews
List of basic types
![[Diagram]](../../diagrams/40/924daa6fe5358cb5096ee20dd7387bea.png) | Three-space extension on the third line |
![[Diagram]](../../diagrams/22/01cd3507f7177d9f5bc3a0dfc0ef2ad3.png) | Three-space extension on the fourth line |
![[Diagram]](../../diagrams/24/7fd1ffc4c5a0e795c2ec986be72ff2a4.png) | Mixed three-space extension |
![[Diagram]](../../diagrams/15/f0adf5e77cd6186766ac9a300a0a3e89.png) | Three-space extension from a wall |
See Extension from a wall
There are pages dealing with invasions in these extensions on the three-space extension invasions path.
[1]
![[Diagram]](../../diagrams/7/c43669cb76b4ef488647ce1c43eb8d00.png) | Advantage 2: light |
, approaching White's wall, is problematic, while extending only to a instead of allows White to play at b.
![[Diagram]](../../diagrams/49/4bb29d7d39b2b9998259ca74abb50a63.png) | Prepare the way |
- press against , preparing for a safe extension to . This sequence avoids the problems of an immediate extension.
--Bill Spight
Charles This idea of Bill's, to use the 3-5 point low approach, press, is a bit more subtle than may seem at first glance. For example, is held back one line, giving White much less chance of fighting on this side.
Path: DiagonalAttachmentPath
· Prev: · Next: DiagonalAttachmentAsInferiorShape
This is a copy of the living page
"Three-space extension" at
Sensei's Library.
2004 the Authors, published under the OpenContent License V1.0.
|