X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Fcontribs%2Flambda_delta%2Fbasic_2%2Fetc%2Fcsup%2Fysteps.etc;fp=matita%2Fmatita%2Fcontribs%2Flambda_delta%2Fbasic_2%2Fetc%2Fcsup%2Fysteps.etc;h=149e7895b899f6e90c6c3529f0f01387698bb86d;hb=53f874fba5b9c39a788085515a4fefe5d29281da;hp=0000000000000000000000000000000000000000;hpb=f7386d0b74f935f07ede4be46d0489a233d68b85;p=helm.git

diff --git a/matita/matita/contribs/lambda_delta/basic_2/etc/csup/ysteps.etc b/matita/matita/contribs/lambda_delta/basic_2/etc/csup/ysteps.etc
new file mode 100644
index 000000000..149e7895b
--- /dev/null
+++ b/matita/matita/contribs/lambda_delta/basic_2/etc/csup/ysteps.etc
@@ -0,0 +1,47 @@
+(**************************************************************************)
+(*       ___                                                              *)
+(*      ||M||                                                             *)
+(*      ||A||       A project by Andrea Asperti                           *)
+(*      ||T||                                                             *)
+(*      ||I||       Developers:                                           *)
+(*      ||T||         The HELM team.                                      *)
+(*      ||A||         http://helm.cs.unibo.it                             *)
+(*      \   /                                                             *)
+(*       \ /        This file is distributed under the terms of the       *)
+(*        v         GNU General Public License Version 2                  *)
+(*                                                                        *)
+(**************************************************************************)
+
+notation "hvbox( h ⊢ break ⦃ L1, break T1 ⦄ • ⭃ * break [ g ] break ⦃ L2 , break T2 ⦄ )"
+   non associative with precedence 45
+   for @{ 'YPRedStepStar $h $g $L1 $T1 $L2 $T2 }.
+
+include "basic_2/substitution/csup.ma".
+include "basic_2/computation/yprs.ma".
+
+(* ITERATED STEP OF HYPER PARALLEL COMPUTATION ON CLOSURES ******************)
+
+inductive ysteps (h) (g) (L1) (T1) (L2) (T2): Prop ≝
+| ysteps_intro: h ⊢ ⦃L1, T1⦄ •⥸*[g] ⦃L2, T2⦄ → (L1 = L2 → T1 = T2 → ⊥) →
+                ysteps h g L1 T1 L2 T2
+.
+
+interpretation "iterated step of hyper parallel computation (closure)"
+   'YPRedStepStar h g L1 T1 L2 T2 = (ysteps h g L1 T1 L2 T2).
+
+(* Basic properties *********************************************************)
+
+lemma ssta_ysteps: ∀h,g,L,T,U,l. ⦃h, L⦄ ⊢ T •[g, l + 1] U →
+                   h ⊢ ⦃L, T⦄ •⭃*[g] ⦃L, U⦄.
+#h #g #L #T #U #l #HTU
+@ysteps_intro /3 width=2/ #_ #H destruct
+elim (ssta_inv_refl … HTU)
+qed.
+
+lemma csup_ysteps: ∀h,g,L1,L2,T1,T2. ⦃L1, T1⦄ > ⦃L2, T2⦄ →
+                   h ⊢ ⦃L1, T1⦄ •⭃*[g] ⦃L2, T2⦄.
+#h #g #L1 #L2 #T1 #T2 #H
+lapply (csup_fwd_cw … H) #H1
+@ysteps_intro /3 width=1/ -H #H2 #H3 destruct
+elim (lt_refl_false … H1)
+qed.