Colorful Helly-type Theorems for the Volume of Intersections of Convex Bodies

TL;DR

This paper establishes a colorful Helly-type theorem in convex geometry, showing that if certain volume conditions hold for all colorful selections, then one family has a large intersection volume, extending classical Helly results.

Contribution

The authors prove a new volume-based Helly-type theorem for convex bodies, linking colorful intersection conditions to a guaranteed large-volume intersection in one family.

Findings

If all colorful 2d intersections have volume ≥ 1, then one family has an intersection volume ≥ d^{-O(d^2)}.

The result generalizes classical Helly theorems to volume considerations in convex geometry.

Provides bounds on intersection volumes based on colorful intersection assumptions.

Abstract

We prove the following Helly-type result. Let $\mathcal{C}_1,\dots,\mathcal{C}_{3d}$ be finite families of convex bodies in $\mathbb{R}^d$. Assume that for any colorful selection of $2d$ sets, $C_{i_k}\in \mathcal{C}_{i_k}$ for each $1\leq k\leq 2d$ with $1\leq i_1<\dots<i_{2d}\leq 3d$, the intersection $\bigcap\limits_{k=1}^{2d} C_{i_k}$ is of volume at least 1. Then there is an $1\leq i \leq 3d$ such that $\bigcap\limits_{C\in \mathcal{C}_i} C$ is of volume at least $d^{-O(d^2)}$.