Classification of Lipschitz simple function germs
Proceedings of the London Mathematical Society
It was shown by Henry and Parusiński in 2003 that the bi-Lipschitz right equivalence of function germs admits moduli. In this article, we introduce the notion of Lipschitz simple function germ and present the complete classification in the complex case. For this, we present several bi-Lipschitz invariants associated to functions germs. In particular, we prove that the lowest degree homogeneous part of a function germ is a bi-Lipschitz invariant and use this to show a weak version of the splitting lemma for bi-Lipschitz equivalence. We improve upon earlier results on bi-Lipschitz triviality of families to show that several families of germs in Arnold's list of unimodal singularities are bi-Lipschitz trivial. A surprising consequence of our result is that a function germ is Lipschitz modal if and only if it deforms to the smooth unimodal family of singularities called (Formula presented.) in Arnold's list.
Nguyen, Nhan; Ruas, Maria; and Trivedi, Saurabh, "Classification of Lipschitz simple function germs" (2020). Journal Articles. 213.