Symplectic structure perturbations and continuity of symplectic invariants

TL;DR

This paper investigates how symplectic invariants from Hamiltonian Floer theory vary under symplectic structure perturbations, establishing continuity and semicontinuity results, and constructing new invariants with applications to symplectic geometry.

Contribution

It introduces a framework for analyzing the stability of symplectic invariants under structure perturbations, including the development of $t$-spectral invariants and their properties.

Findings

Spectral invariants and boundary depth are continuous under certain symplectic perturbations.

Construction of $t$-spectral invariants that are upper semicontinuous.

Embedding of infinite-dimensional spaces into Hamiltonian diffeomorphism groups.

Abstract

This paper studies how symplectic invariants created from Hamiltonian Floer theory change under the perturbations of symplectic structures, not necessarily in the same cohomology class. These symplectic invariants include spectral invariants, boundary depth, and (partial) symplectic quasi-states. This paper can split into two parts. In the first part, we prove some energy estimations that control the shifts of symplectic action functionals. These directly imply positive conclusions on the continuity of spectral invariants and boundary depth, in some important cases including any symplectic surface $\Sigma_{g \geq1}$ and any closed symplectic manifold $M$ with $\dim_{\mathcal K} H^2(M; \mathcal K) = 1$. This follows by applications on some rigidity of the subsets of a symplectic manifold in terms of heaviness and superheaviness, as well as on the continuity property of some symplectic capacities. In the second part, we generalize the construction in the first part to any closed symplectic manifold. In particular, to deal with the change of Novikov rings from symplectic structure perturbations, we construct a family of variant Floer chain complexes over a common Novikov-type ring. In this set-up, we define a new family of spectral invariants called $t$-spectral invariants, and prove that they are upper semicontinuous under the symplectic structure perturbations. This implies a quasi-isometric embedding from $(\mathbb R^{\infty}, |-|_{\infty})$ to $({\widetilde {\rm Ham}}(M, \omega), |-|_{\rm Hofer})$ under some dynamical assumption, imitating a result from Usher.