published on January 20, 2026
From connecting the dots to conjugacy of dynamical systems
By Pierre Arnoux
By Diana Davis
Appears in collection : Differential Geometry, Billiards, and Geometric Optics / Géométrie différentielle, billards et optique géométrique
Periodic trajectories in polygons are rare and beautiful, and have several surprising properties. During the lockdown period in 2020, we wrote a Sage program to draw every periodic trajectory on every regular polygon with an odd number of edges. I’ll explain the underlying structure, and show lots of pictures from this vast menagerie. This is joint work with Samuel Lelièvre.