Pentagon capacity code
= Pentagon capacity code
{title2=$\{(j,2j):j\in\mathbb Z/5\mathbb Z\}$}
These five words are independent in the strong square of the <cycle graph> $C_5$: a nonzero difference is a nonedge in the first or the second coordinate. A three-dimensional orthonormal representation with common vertical squared component $1/\sqrt5$ proves the matching upper bound. Consequently $c(C_5)=\vartheta(C_5)=\sqrt5$.