Canonical orientations in Heegaard Floer theory
Mohammed Abouzaid, Ciprian Manolescu
TL;DR
The paper develops Heegaard Floer theory over the integers by introducing canonical orientations arising from coupled Spin structures on Lagrangian tori, establishing naturality and functoriality with integral coefficients for HF, sutured HF, and link HF, and providing a new integer-coefficient proof of the surgery exact triangle along with a Z-coefficient version of involutive HF. It extends these constructions to twisted coefficients and to sutured and multi-basepoint variants, yielding a cohesive integral framework across closed, sutured, and link invariants. The work combines Spin/Pin geometry with Perutz’s symplectic perspective to achieve sign-controlled, naturality-rich invariants with potential implications for integral cobordism maps in low-dimensional topology. Overall, the results place Heegaard Floer theory over $\mathbb{Z}$ on solid footing, enabling finer arithmetic and functorial applications in 3- and 4-dimensional topology.
Abstract
We set up Heegaard Floer theory over the integers, using canonical orientations coming from coupled Spin structures on the Lagrangian tori. We prove naturality of Heegaard Floer homology, sutured Floer homology, and link Floer homology over $\mathbb{Z}$. We give a new proof of the surgery exact triangle in this context, as well as a definition of involutive Heegaard Floer homology over $\mathbb{Z}$.
