Sets with small angles in self-contracted curves

Abstract

We study metric spaces with bounded rough angles. E. Le Donne, T. Rajala and E. Walsberg implicitly used this notion to show that infinite snowflakes can not be isometrically embedded into finite dimensional Banach spaces. We show that bounded non-rectifiable self-contracted curves contain metric subspaces with bounded rough angles. Which provides rectifiability of bounded self-contracted curves in a wide class of metric spaces including reversible $C^{\infty }$-Finsler manifolds, locally compact $CAT(k)$-spaces with locally extendable geodesics and locally compact Busemann spaces with locally extendable geodesics. We also extend the result on non embeddability of infinite snowflakes to this class of spaces.

Theorem 4 is new and the text is sufficiently reorganized