proposition: Lemma fidentity_twoarrow_cat : fidentity twoarrow_cat = twoarrow_functor twoarrow_cat (catyd_arrow a0') (catyd_arrow a1').
proof: Proof. cp twoarrow_cat_axioms. app functor_twoarrow_eq2. rww fidentity_axioms. rww source_fidentity. rww target_fidentity. rww fmor_fidentity. ap mor_twoarrow_cat. rww fmor_fidentity; ap mor_twoarrow_cat. Qed.
imports: Arith cat_examples cardinal fc_limits