The Erdős-Ko-Rado Theorem in ${\ell }_2$-Norm

Biao Wu, Huajun Zhang

The codegree squared sum ${\mathrm{co}}_2(\mathcal{F})$ of a family (hypergraph) $\mathcal{F}\subseteq \left(\genfrac{}{}{0ex}{}{[n]}{k}\right)$ is defined to be the sum of codegrees squared $d(E{)}^2$ over all $E\in \binom…