Beschreibung:
<jats:title>Abstract</jats:title><jats:p>We address the problem of computing the fundamental group of a symplectic<jats:italic>S</jats:italic><jats:sup>1</jats:sup>-manifold for non-Hamiltonian actions on compact manifolds, and for Hamiltonian actions on non-compact manifolds with a proper moment map. We generalize known results for compact manifolds equipped with a Hamiltonian<jats:italic>S</jats:italic><jats:sup>1</jats:sup>-action. Several examples are presented to illustrate our main results.</jats:p>