kinks

kinks(k: PlanarDiagram, crossing=None) → set

Returns the set of kinks in the planar diagram. A kink is given as an endpoint that defines a face. Note that the twin of a kink is not a kink.

A kink is a loop at a crossing where traversal in a counterclockwise direction returns to the same node.

Args:

k (PlanarDiagram): The planar diagram. crossing: If provided, only kinks attached to the specified crossing will be considered.

Returns:

set: A set of kinks.