proposition: Lemma homcompA (a b c d : C) (h : {hom c, d}) (g : {hom b, c}) (f : {hom a, b}) : [hom [hom h \o g] \o f] = [hom h \o [hom g \o f]].
proof: Proof. by move: f g h => [? ?] [? ?] [? ?]; apply hom_ext. Qed.
imports: mathcomp(all_ssreflect) mathcomp(boolp) monae_lib HB(structures)