Published online by Cambridge University Press: 20 November 2018
We address the problem of computing the fundamental group of a symplectic ${{S}^{1}}$-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 ${{S}^{1}}$-action. Several examples are presented to illustrate our main results.
Both authors were partially supported by FCT through program POCTI/FEDER; the first author was partially supported by FCT through grant POCTI/MAT/57888/2004 and by Fundação Calouste Gulbenkian
This generalized moment map is a special case of a Lie group-valued moment map (see [OR] and the references therein).