proposition: Lemma ex9_propf: right_directed_on r I -> equivalence_on (graph_on ex9_srel ex9_G) ex9_G.
proof: Proof. move => h. set S := InductiveSystem or sr h fgE dE fgf df function_f compose_f identity_f. by move: (inl_equiv_esr S) => [ha hb]. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)