## Replying to:

3 January 2007 18:44, by Christian Mercat
Dear Claire,
> I don’t understand the dual graph.
It’s about putting things into boxes.
> In your drawing of the trefoil knot, you ignore a lot of lines in the dual graph.
I don’t. The one outside are walls, they can not be crossed. The thread "bounces back" inside the triangle.
> What’s the purpose of the dual graph if you don’t follow it? And how do you find the dual graph without the original knot?
You have to begin somewhere. If you have a graph, the way to build the dual graph is to put a dual vertex "in the middle" of each face. Each edge separates 2 faces, which are associated (...)