C^0 Lagrangian Monodromy

Abstract

We prove that (under appropriate orientation assumptions), the action of a Hamiltonian homeomorphism ϕon the cohomology of a relatively exact Lagrangian fixed by ϕis the identity. This extends results of Hu-Lalonde-Leclercq and the author in the setting of Hamiltonian diffeomorphisms. We also prove a similar result regarding the action of ϕon relative cohomology.

v2: 12 pages. Accepted version. Expanded in response to referee report. Comments still welcome!