Finite selection of relation generators in the stable Morse fundamental group presentation

Determine an intrinsic, effective procedure to select a finite subset of the potentially infinite family of relation generators used to define the normal subgroup R in the stable Morse fundamental group construction for generic stable Morse data Xi = (f, X) on a closed manifold M with base point ⋆, so that the resulting quotient L/R still presents π1(M,⋆). The goal is to specify a concrete selection criterion or algorithm, derived from the moduli spaces and “bouncing” trajectories described in the paper, that yields a finite generating set of relations sufficient to produce the isomorphism L/R ≅ π1(M,⋆).

Background

The paper constructs a group L of “Morse loops” and a normal subgroup R generated by preferred “Morse relations” from moduli spaces of augmentation-like and bouncing trajectories associated to generic stable Morse data Xi = (f, X) on M × R{N_+} × R{N_-}. The evaluation map then induces an isomorphism L/R ≅ π1(M,⋆).

Unlike in classical Morse theory, the stable setting may produce an infinite family of generators for R. While it is known a posteriori that only finitely many relations are needed to present π1(M,⋆), the authors’ construction does not presently provide a method to identify such a finite subset from the infinite family, motivating the need for a concrete selection procedure consistent with their dynamical framework.

References

In contrast to (non stable) Morse theory, the present description of the relations does not lead to numerical constraints. Indeed, the family of generators for the relations mentioned in the statement may be infinite, and although we a posteriori know that only finitely of them are required, it is not clear from our description how to proceed to such a selection.

Fundamental group in stable Morse theory (2410.07802 - Barraud et al., 10 Oct 2024) in Remark following Theorem thm:Main, Introduction