  In his work on the foundations of geometry, Hilbert observed that a formula
which appeared in works by Beltrami, Cayley, and Klein, gives rise to a
complete metric on any bounded convex domain. Some decades later, Garrett
Birkhoff and Hans Samelson noted that this metric has interesting applications,
when considering certain maps of convex cones that contract the metric. Such
situations have since arisen in many contexts, pure and applied, and could be
called nonlinear Perron-Frobenius theory. This note centers around one
dynamical aspect of this theory.
