1 (* Basic_1: was by definition: ty3_bind *)
2 (* Basic_2A1: was by definition: nta_bind ntaa_bind *)
5 (* Basic_2A1: was by definition: nta_pure ntaa_pure *)
8 (* Basic_1: was: ty3_gen_bind *)
9 (* Basic_2A1: was: nta_inv_bind1 ntaa_inv_bind1 *)
12 (* Basic_1: was by definition: ty3_abst *)
13 (* Basic_2A1: was by definition: nta_ldec *)
16 (* Advanced properties ******************************************************)
18 | ntaa_cast: ∀L,T,U,W. ntaa h L T U → ntaa h L U W → ntaa h L (ⓝU. T) U
20 lemma nta_cast_alt: ∀h,L,T,W,U. ⦃h, L⦄ ⊢ T : W → ⦃h, L⦄ ⊢ T : U → ⦃h, L⦄ ⊢ ⓝW.T : U.
21 #h #L #T #W #U #HTW #HTU
22 lapply (nta_mono … HTW … HTU) #HWU
23 elim (nta_fwd_correct … HTU) -HTU /3 width=3/