HAMILTONIAN CIRCLE ACTIONS WITH MINIMAL FIXED SETS
HAMILTONIAN CIRCLE ACTIONS WITH MINIMAL FIXED SETS
Consider an effective Hamiltonian circle action on a compact symplectic $2n$-dimensional manifold $(M, \omega)$. Assume that the fixed set $M^{S^1}$ is {\em minimal}, in two senses: it has exactly two components, $X$ and $Y$, and $\dim(X) + \dim(Y) = \dim(M) - 2$. We prove that the integral cohomology ring and …