English

Random section and random simplex inequality

Metric Geometry 2022-02-08 v2

Abstract

Consider some convex body KRdK\subset\mathbb R^d. Let X1,,XkX_1,\dots, X_k, where kdk\leq d, be random points independently and uniformly chosen in KK, and let ξk\xi_k be a uniformly distributed random linear kk-plane. We show that for pd+k+1p\geq-d+k+1, EKξkd+pcd,k,pKkEconv(0,X1,,Xk)p, \mathbb E\,|K\cap\xi_k|^{d+p}\leq c_{d,k,p} \cdot|K|^k\, \,\mathbb E\,|\mathrm{conv}(0,X_1, \dots,X_k)|^p, where |\cdot| and conv\mathrm{conv} denote the volume of correspondent dimension and the convex hull. The constant cd,k,pc_{d,k,p} is such that for k>1k>1 the equality holds if and only if KK is an ellipsoid centered at the origin, and for k=1k=1 the inequality turns to equality. If p=0p=0, then the inequality reduces to the Busemann intersection inequality, and if k=dk=d -- to the Busemann random simplex inequality. We also present an affine version of this inequality which similarly generalizes the Schneider inequality and the Blaschke-Gr\"omer inequality.

Keywords

Cite

@article{arxiv.2007.06743,
  title  = {Random section and random simplex inequality},
  author = {Alexander E. Litvak and Dmitry Zaporozhets},
  journal= {arXiv preprint arXiv:2007.06743},
  year   = {2022}
}
R2 v1 2026-06-23T17:05:42.597Z