A homological criterion for the almost-existence of Hamiltonian chords
Antoine Rodrigues
TL;DR
The paper develops a homological criterion for the almost-existence of Hamiltonian chords near a given energy level inside a Liouville domain. Central to the approach is a relative Lagrangian Hofer–Zehnder capacity derived from wrapped Floer homology, together with spectral invariants that bound this capacity by a wrapped-Floer–based symplectic capacity $c_{SH}$. The main result shows that if there exists a Lagrangian homology class $eta eq0$ with $i_L(eta)=0$ but whose shriek image remains nontrivial in a relative setting, then almost all nearby energy levels carry a Hamiltonian chord; a key corollary is that if $SH_*(W,L)=0$, almost-existence holds for any hypersurface transverse to $L$. The framework unifies capacities and homologies to produce broad almost-existence results, with concrete implications for subcritical/flexible Weinstein domains and displaceable Lagrangians.
Abstract
We establish a criterion on wrapped Floer homology of an exact Lagrangian sub- manifold in a Liouville domain, which ensures the almost-existence of Hamiltonian chords near a given energy level. To this purpose we introduce a relative version of the coisotropic Hofer-Zehnder capacity, and compare it with some other capacities that are defined using filtered wrapped Floer homology. Our main application is the almost- existence of Hamiltonian chords near any hypersurface if the wrapped Floer homology vanishes.
