Harder-Narasimhan filtrations of persistence modules: metric stability

Abstract: The Harder-Narasimhan types are a family of discrete isomorphism invariants for representations of finite quivers. Previously (arXiv:2303.16075), we evaluated their discriminating power in the context of persistence modules over a finite poset, including multiparameter persistence modules (over a finite grid). In particular, we introduced the skyscraper invariant and proved it was strictly finer than the rank invariant. In order to study the stability of the skyscraper invariant, we extend its definition from the finite to the infinite setting and consider multiparameter persistence modules over $\mathbb Z ^n$ and $\mathbb R^n$. We then establish an erosion-type stability result for this version of the skyscraper invariant.