In
geometry, a
Coxeter–Dynkin diagram (or
Coxeter diagram,
Coxeter graph) is a
graph with numerically labeled edges (called
branches) representing the spatial relations between a collection of
mirrors (or reflecting
hyperplanes). It describes a
kaleidoscopic construction: each graph "node" represents a mirror (domain
facet) and the label attached to a branch encodes the
dihedral angle order between two mirrors (on a domain
ridge). An unlabeled branch implicitly represents order-3.