On the Carath\'eodory number for strong convexity

Abstract

We give an improvement of the Carath\'eodory theorem for strong convexity (ball convexity) in $\mathbb R^n$, reducing the Carath\'eodory number to $n$ in several cases; and show that the Carath\'eodory number cannot be smaller than $n$ for an arbitrary gauge body $K$. We also give an improved topological criterion for one convex body to be a Minkowski summand of another.