1 (**************************************************************************)
4 (* ||A|| A project by Andrea Asperti *)
6 (* ||I|| Developers: *)
7 (* ||T|| The HELM team. *)
8 (* ||A|| http://helm.cs.unibo.it *)
10 (* \ / This file is distributed under the terms of the *)
11 (* v GNU General Public License Version 2 *)
13 (**************************************************************************)
15 include "basic_2/dynamic/cnv_eval.ma".
16 include "basic_2/dynamic/nta_preserve.ma".
18 (* NATIVE TYPE ASSIGNMENT FOR TERMS *****************************************)
20 (* Properties with evaluations for rt-transition on terms *******************)
22 lemma nta_typecheck_dec (a) (h) (G) (L):
23 ∀T,U. Decidable … (⦃G,L⦄ ⊢ T :[a,h] U).
24 /2 width=1 by cnv_dec/ qed-.
26 (* Basic_1: uses: ty3_inference *)
27 lemma nta_inference_dec (a) (h) (G) (L) (T):
28 ∨∨ ∃U. ⦃G,L⦄ ⊢ T :[a,h] U
29 | ∀U. (⦃G,L⦄ ⊢ T :[a,h] U → ⊥).
31 elim (cnv_dec a h G L T)
32 [ /3 width=1 by cnv_nta_sn, or_introl/
33 | /4 width=2 by nta_fwd_cnv_sn, or_intror/