diamond property of reduction!

[helm.git] / matita / matita / contribs / lambdadelta / basic_2 / rt_transition / lfpr_drops.ma

diff --git a/matita/matita/contribs/lambdadelta/basic_2/rt_transition/lfpr_drops.ma b/matita/matita/contribs/lambdadelta/basic_2/rt_transition/lfpr_drops.ma
index b3deebd859e0ea411d626ca095f62897ec2f578d..3156e7252cf303c9721374975a84951a3919e93f 100644 (file)
--- a/matita/matita/contribs/lambdadelta/basic_2/rt_transition/lfpr_drops.ma
+++ b/matita/matita/contribs/lambdadelta/basic_2/rt_transition/lfpr_drops.ma
@@ -30,3 +30,11 @@ lemma lfpr_drops_conf: ∀h,G. dropable_sn (cpm 0 h G).
 
 lemma lfpr_drops_trans: ∀h,G. dropable_dx (cpm 0 h G).
 /2 width=5 by lfxs_dropable_dx/ qed-.
+
+lemma lfpr_inv_lref_sn: ∀h,G,L1,L2,i. ⦃G, L1⦄ ⊢ ➡[h, #i] L2 → ∀I,K1,V1. ⬇*[i] L1 ≡ K1.ⓑ{I}V1 →
+                        ∃∃K2,V2. ⬇*[i] L2 ≡ K2.ⓑ{I}V2 & ⦃G, K1⦄ ⊢ ➡[h, V1] K2 & ⦃G, K1⦄ ⊢ V1 ➡[h] V2.
+/2 width=3 by lfxs_inv_lref_sn/ qed-.
+
+lemma lfpr_inv_lref_dx: ∀h,G,L1,L2,i. ⦃G, L1⦄ ⊢ ➡[h, #i] L2 → ∀I,K2,V2. ⬇*[i] L2 ≡ K2.ⓑ{I}V2 →
+                        ∃∃K1,V1. ⬇*[i] L1 ≡ K1.ⓑ{I}V1 & ⦃G, K1⦄ ⊢ ➡[h, V1] K2 & ⦃G, K1⦄ ⊢ V1 ➡[h] V2.
+/2 width=3 by lfxs_inv_lref_dx/ qed-.