Expansion of coset graphs of PSL_2(F_p)

Péter P. Varjú

Let $G$ be a finite group and let $H_1,H_2<G$ be two subgroups. In this paper, we are concerned with the bipartite graph whose vertices are $G/H_1\cup G/H_2$ and a coset $g_1{H}_1$ i…