Floer-type bipersistence modules and rectangle barcodes

Abstract

We study the bipersistence modules obtained from the action-window homology of Floer-type complexes over $\Lambda^{\mathbb{F},\{0\}}=\mathbb{F}$. We prove that these modules are rectangle-decomposable and establish an explicit dictionary between their graded rectangle barcodes and the classical one-parameter barcodes. This dictionary is an isometry for the bottleneck distance. Consequently, the interleaving and bottleneck distances coincide on this class of bipersistence modules: the optimal constant in algebraic stability improves from $3$ for general rectangle-decomposable $\mathbb{R}^2$-indexed modules to $1$, even though the rectangles that occur are not blocks. The resulting rectangle barcodes depend $1$-Lipschitz-continuously on the Morse function in the uniform norm and on the Hamiltonian diffeomorphism in Hofer's metric. Their corner multiplicities record critical points and one-periodic Hamiltonian orbits degree by degree and filtration level by filtration level, while their geometry displays spectral invariants, boundary depth, and spectral spreads. Thus the rectangle barcode gives a geometric presentation, rather than a refinement, of the classical barcode.