Non‐algebraic Convergence Proofs for Continuous‐Time Fictitious Play

In this technical note we use insights from the theory of projective geometry to provide novel and non‐algebraic proofs of convergence of continuous‐time fictitious play for a class of games. As a corollary we obtain a kind of equilibrium selection result, whereby continuous‐time fictitious play converges to a particular equilibrium contained in a continuum of equivalent equilibria for symmetric 4×4 zero‐sum games.