proposition: Lemma connector_eq i j x : x \in p i -> x \in p j -> i = j.
proof: Proof. move => Hi Hj. apply: contraTeq isT => /(conn_disjoint conn_p)/setP/(_ x). by rewrite !inE Hi Hj. Qed.
imports: mathcomp(all_ssreflect) GraphTheory(edone preliminaries digraph mgraph sgraph set_tac)