The Morse complex is an $\infty$-functor
Guillem Cazassus
TL;DR
This work develops a higher-categorical Morse-theory framework that realizes Morse-theoretic data as $infty$-functors into algebraic structures capturing multiplicative and comultiplicative features. It introduces perturbation-parameterized moduli spaces built from grafted forests and biforests (the $n$-grafted bimultiplihedra) to achieve coherent composition and boundary relations, assembling them into weak Kan models $f$-Bialg, $f$-Alg, and $f$-Coalg. The main results show that, for smooth manifolds, the Morse complex yields a functor to $f$-coalgebras (and dually to $A_infty$-algebras via cochains), while for compact Lie groups (or monoids) the Morse theory produces an $infty$-functor into $f ext{-} ext{Bialg}$ with coherent group-action-induced module structures. This provides a rigorous higher-categorical realization of Morse theory compatible with equivariant settings and suggests deep connections to Fukaya-type categories and extended topological field theories.
Abstract
We provide two versions of the statement in the title. First, when the source is the category of smooth manifolds, we construct a simplicial map to a weak Kan complex whose objects are A-infinity coalgebras. Second, when the source is the category of compact Lie groups (or more generally, compact Lie monoids), the target is a weak Kan complex whose objects consist in $f$-bialgebras, as defined in [CHM24]. We also establish a statement describing module structures induced by group actions, as conjectured in [CHM24].
