Exotic symplectomorphisms and contact circle action

Igor Uljarevic, University of Belgrade

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An exotic symplectomorphism is a symplectomorphism that is not isotopic to the identity through compactly supported symplectomorphisms.Using Floer-theoretic methods, we prove that the non-existence of an exotic symplectomorphism on the standard symplectic ball, $\mathbb{B}^{2n},$ implies a rather strict topological condition on the free contact circle actions on the standard contact sphere, $\mathbb{S}^{2n-1}.$ We also prove an analogue for a Liouville domain and contact circle actions on its boundary. Applications include results on the symplectic mapping class group, the fundamental group of the group of contactomorphisms, and exotic contact structures on $\mathbb{S}^3.$ The talk is based on joint work with Dusan Drobnjak.