Obstructions to a small hyperbolicity in Helly graphs

Feodor F. Dragan, Heather M. Guarnera

It is known that for every graph $G$ there exists the smallest Helly graph $\mathcal{H}(\mathcal{G})$ into which $G$ isometrically embeds ($\mathcal{H}(\mathcal{G})$ is called the injective hull of $G$) such th…