The medial axis of closed bounded sets is Lipschitz stable with respect to the Hausdorff distance under ambient diffeomorphisms

We prove that the medial axis of closed sets is Hausdorff stable in the following sense: Let 𝒮⊆ℝ^d be (fixed) closed set (that contains a bounding sphere). Consider the space of C^1,1 diffeomorphisms of ℝ^d to itself, which keep the bounding sphere invariant. The map from this space of diffeomorphisms (endowed with some Banach norm) to the space of closed subsets of ℝ^d (endowed with the Hausdorff distance), mapping a diffeomorphism F to the closure of the medial axis of F(𝒮), is Lipschitz. This extends a previous stability result of Chazal and Soufflet on the stability of the medial axis of C^2 manifolds under C^2 ambient diffeomorphisms.