On the fixed points of a Hamiltonian diffeomorphism in presence of fundamental group

Let M be a weakly monotone symplectic manifold, and H be a time-dependent Hamiltonian; we assume that the periodic orbits of the corresponding time-dependent Hamiltonian vector field are non-degenerate. We construct a refined version of the Floer chain complex associated to these data and any regular covering of M, and derive from it new lower bounds for the number of periodic orbits. We prove in particular that if the fundamental group of M is finite and solvable or simple, then the number of periodic orbits is not less than the minimal number of generators of the fundamental group. For a general closed symplectic manifold with infinite fundamental group, we show the existence of 1-periodic orbit of Conley-Zehnder index 1-n for any non-degenerate 1-periodic Hamiltonian system.Comment: revised and extended version; the estimates for periodic orbits of index 2-n adde