Here's an example.
![[Diagram]](../../diagrams/43/a5cf6aab17b58a037590982a8c19b31c.png)
Coupling on the edge
Now White is in trouble:
![[Diagram]](../../diagrams/11/bd3880a7680ae86e2794c74c7f0c4cef.png)
Two cutting points
Black will either be able to cut at a, or start a dangerous ko by cutting at b.
![[Diagram]](../../diagrams/36/fdc8e44fe91ac2c6be2856c517839961.png)
White's correct response
When Black plays
, White must answer this way, with
.
The two white territories, on the left and right, are linked in a subtle relationship we can call 'coupling'.
![[Diagram]](../../diagrams/46/b0542116d7624825fb74517f7bba040a.png)
White's correct response (continuation)
After that White can defend territory easily.
In this position the coupling effect is worth two extra points for Black.
Charles Matthews