English

Hardness of approximation of centered convex bodies by polytopes

Functional Analysis 2026-02-27 v1

Abstract

The distance between convex bodies K,LRnK, L \subseteq \R^n is defined as d(K,L)=inf{λ1: LxT(Ky)λ(Lx)}, d(K,L)= \inf \left\{ \lambda \ge 1: \ L-x \subseteq T (K-y) \subseteq \lambda (L-x) \right\}, where the infimum is taken over all x,yRnx,y \in \R^n and all invertible linear operators T:RnRnT: \R^n \to \R^n. If both bodies are centrally symmetric, then the shifts xx and yy can be chosen to be 00. In this case, any convex symmetric body KK can be approximated by a polytope PP with at most N(n,ecn)N \in (n, e^{cn}) vertices so that PKλP P \subseteq K \subseteq \lambda P where λ=O(nlogN)\lambda= O \left(\sqrt{\frac{n}{\log N}} \right) up to logarithmic factors. We prove that approximating a general centered convex body by a polytope requires a significantly larger number of vertices compared to the symmetric case. More precisely, there exists a convex body KRnK \subseteq \R^n whose barycenter coincides with the origin, such that any polytope PP satisfying PKcnlogNP P \subseteq K \subseteq c \, \frac{n}{\log N} P must have at least NN vertices, provided that N(Cn2,ecn)N \in (Cn^2, e^{cn}). Moreover, we prove that the same bound holds for approximating a centered convex body with a polytope having NN facets instead of NN vertices.

Keywords

Cite

@article{arxiv.2602.23034,
  title  = {Hardness of approximation of centered convex bodies by polytopes},
  author = {Han Huang and Mark Rudelson},
  journal= {arXiv preprint arXiv:2602.23034},
  year   = {2026}
}