proposition: Lemma Diso'' (F G: diGraph) (f: F -> G) (g: G -> F): cancel f g -> cancel g f -> (forall x y, x--y -> f x -- f y) -> (forall x y, x--y -> g x -- g y) -> diso F G.
proof: Proof. move=> can_f can_g H H'. apply: Diso' (can_f) can_g _. abstract by move => x y; apply/idP/idP => [/H'|/H //]; rewrite !can_f. Defined.
imports: HB(structures) Coq(Setoid CMorphisms) mathcomp(all_ssreflect) GraphTheory(edone preliminaries bij)