fact: Definition graph_rel : rel (graph_node * bool) := fun x y => match x, y with | (inl x, true), (inr y, false) => (x \in edom c) && (edges c x == y) | (inr y, false), (inr y', true) => [exists s, [&& s \in conodes c, y \in s, y' \in s & y != y']] | (inr y, true), (inl x, false) => (x \in edom c) && (edges c x == y) | (inl x, false), (inl x', true) => [exists s, [&& s \in nodes c, x \in s, x' \in s & x != x']] | _, _ => false end.
imports: mathcomp(all_ssreflect ssralg fingroup zmodp poly ssrnum) mathcomp(matrix perm) ssr_ext ssralg_ext fdist subgraph_partition tanner