Uniform covers theorem
= Uniform covers theorem
If $\mathcal C$ is a $k$-uniform cover of $[n]$ and $S\subseteq\mathbb R^n$ is a <Euclidean body>, then
$$
|S|^k\leq\prod_{A\in\mathcal C}|S_A|.
$$
Slicing in one coordinate, applying the theorem inductively to each slice, and then applying <Hölder's inequality> to the $k$ projected slice functions proves the inequality.