proposition: Lemma class_neq@{} : forall q r, ~ (equiv q r) -> ' q <> ' r.
proof: Proof. intros q r E1 E2;apply E1;apply classes_eq_related, E2. Qed.
imports: HoTT.HIT.quotient HoTT.Basics.Trunc HoTT.Classes.interfaces.abstract_algebra HoTT.Classes.theory.dec_fields