Here's an example.
![[Diagram]](../../diagrams/26/f874d35249dbfa6db486d5e8299e43d4.png)
Coupling on the edge
Now White is in trouble:
![[Diagram]](../../diagrams/31/3730b73996218825eaa518d4e2e153b9.png)
Two cutting points
Black will either be able to cut at a, or start a dangerous ko by cutting at b.
![[Diagram]](../../diagrams/37/25c2c09fca238dd9a4333bae9aeb40d7.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/38/efe941b24d3ac8e8cc89d41f00cb50ac.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