--- /dev/null
+(**************************************************************************)
+(* ___ *)
+(* ||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 *)
+(* *)
+(**************************************************************************)
+
+include "basic_2/notation/relations/lrsubeqd_5.ma".
+include "basic_2/static/lsubr.ma".
+include "basic_2/static/da.ma".
+
+(* LOCAL ENVIRONMENT REFINEMENT FOR DEGREE ASSIGNMENT ***********************)
+
+inductive lsubd (h) (o) (G): relation lenv ≝
+| lsubd_atom: lsubd h o G (⋆) (⋆)
+| lsubd_pair: ∀I,L1,L2,V. lsubd h o G L1 L2 →
+ lsubd h o G (L1.ⓑ{I}V) (L2.ⓑ{I}V)
+| lsubd_beta: ∀L1,L2,W,V,d. ⦃G, L1⦄ ⊢ V ▪[h, o] d+1 → ⦃G, L2⦄ ⊢ W ▪[h, o] d →
+ lsubd h o G L1 L2 → lsubd h o G (L1.ⓓⓝW.V) (L2.ⓛW)
+.
+
+interpretation
+ "local environment refinement (degree assignment)"
+ 'LRSubEqD h o G L1 L2 = (lsubd h o G L1 L2).
+
+(* Basic forward lemmas *****************************************************)
+
+lemma lsubd_fwd_lsubr: ∀h,o,G,L1,L2. G ⊢ L1 ⫃▪[h, o] L2 → L1 ⫃ L2.
+#h #o #G #L1 #L2 #H elim H -L1 -L2 /2 width=1 by lsubr_pair, lsubr_beta/
+qed-.
+
+(* Basic inversion lemmas ***************************************************)
+
+fact lsubd_inv_atom1_aux: ∀h,o,G,L1,L2. G ⊢ L1 ⫃▪[h, o] L2 → L1 = ⋆ → L2 = ⋆.
+#h #o #G #L1 #L2 * -L1 -L2
+[ //
+| #I #L1 #L2 #V #_ #H destruct
+| #L1 #L2 #W #V #d #_ #_ #_ #H destruct
+]
+qed-.
+
+lemma lsubd_inv_atom1: ∀h,o,G,L2. G ⊢ ⋆ ⫃▪[h, o] L2 → L2 = ⋆.
+/2 width=6 by lsubd_inv_atom1_aux/ qed-.
+
+fact lsubd_inv_pair1_aux: ∀h,o,G,L1,L2. G ⊢ L1 ⫃▪[h, o] L2 →
+ ∀I,K1,X. L1 = K1.ⓑ{I}X →
+ (∃∃K2. G ⊢ K1 ⫃▪[h, o] K2 & L2 = K2.ⓑ{I}X) ∨
+ ∃∃K2,W,V,d. ⦃G, K1⦄ ⊢ V ▪[h, o] d+1 & ⦃G, K2⦄ ⊢ W ▪[h, o] d &
+ G ⊢ K1 ⫃▪[h, o] K2 &
+ I = Abbr & L2 = K2.ⓛW & X = ⓝW.V.
+#h #o #G #L1 #L2 * -L1 -L2
+[ #J #K1 #X #H destruct
+| #I #L1 #L2 #V #HL12 #J #K1 #X #H destruct /3 width=3 by ex2_intro, or_introl/
+| #L1 #L2 #W #V #d #HV #HW #HL12 #J #K1 #X #H destruct /3 width=9 by ex6_4_intro, or_intror/
+]
+qed-.
+
+lemma lsubd_inv_pair1: ∀h,o,I,G,K1,L2,X. G ⊢ K1.ⓑ{I}X ⫃▪[h, o] L2 →
+ (∃∃K2. G ⊢ K1 ⫃▪[h, o] K2 & L2 = K2.ⓑ{I}X) ∨
+ ∃∃K2,W,V,d. ⦃G, K1⦄ ⊢ V ▪[h, o] d+1 & ⦃G, K2⦄ ⊢ W ▪[h, o] d &
+ G ⊢ K1 ⫃▪[h, o] K2 &
+ I = Abbr & L2 = K2.ⓛW & X = ⓝW.V.
+/2 width=3 by lsubd_inv_pair1_aux/ qed-.
+
+fact lsubd_inv_atom2_aux: ∀h,o,G,L1,L2. G ⊢ L1 ⫃▪[h, o] L2 → L2 = ⋆ → L1 = ⋆.
+#h #o #G #L1 #L2 * -L1 -L2
+[ //
+| #I #L1 #L2 #V #_ #H destruct
+| #L1 #L2 #W #V #d #_ #_ #_ #H destruct
+]
+qed-.
+
+lemma lsubd_inv_atom2: ∀h,o,G,L1. G ⊢ L1 ⫃▪[h, o] ⋆ → L1 = ⋆.
+/2 width=6 by lsubd_inv_atom2_aux/ qed-.
+
+fact lsubd_inv_pair2_aux: ∀h,o,G,L1,L2. G ⊢ L1 ⫃▪[h, o] L2 →
+ ∀I,K2,W. L2 = K2.ⓑ{I}W →
+ (∃∃K1. G ⊢ K1 ⫃▪[h, o] K2 & L1 = K1.ⓑ{I}W) ∨
+ ∃∃K1,V,d. ⦃G, K1⦄ ⊢ V ▪[h, o] d+1 & ⦃G, K2⦄ ⊢ W ▪[h, o] d &
+ G ⊢ K1 ⫃▪[h, o] K2 & I = Abst & L1 = K1. ⓓⓝW.V.
+#h #o #G #L1 #L2 * -L1 -L2
+[ #J #K2 #U #H destruct
+| #I #L1 #L2 #V #HL12 #J #K2 #U #H destruct /3 width=3 by ex2_intro, or_introl/
+| #L1 #L2 #W #V #d #HV #HW #HL12 #J #K2 #U #H destruct /3 width=7 by ex5_3_intro, or_intror/
+]
+qed-.
+
+lemma lsubd_inv_pair2: ∀h,o,I,G,L1,K2,W. G ⊢ L1 ⫃▪[h, o] K2.ⓑ{I}W →
+ (∃∃K1. G ⊢ K1 ⫃▪[h, o] K2 & L1 = K1.ⓑ{I}W) ∨
+ ∃∃K1,V,d. ⦃G, K1⦄ ⊢ V ▪[h, o] d+1 & ⦃G, K2⦄ ⊢ W ▪[h, o] d &
+ G ⊢ K1 ⫃▪[h, o] K2 & I = Abst & L1 = K1. ⓓⓝW.V.
+/2 width=3 by lsubd_inv_pair2_aux/ qed-.
+
+(* Basic properties *********************************************************)
+
+lemma lsubd_refl: ∀h,o,G,L. G ⊢ L ⫃▪[h, o] L.
+#h #o #G #L elim L -L /2 width=1 by lsubd_pair/
+qed.
+
+(* Note: the constant 0 cannot be generalized *)
+lemma lsubd_drop_O1_conf: ∀h,o,G,L1,L2. G ⊢ L1 ⫃▪[h, o] L2 →
+ ∀K1,c,k. ⬇[c, 0, k] L1 ≡ K1 →
+ ∃∃K2. G ⊢ K1 ⫃▪[h, o] K2 & ⬇[c, 0, k] L2 ≡ K2.
+#h #o #G #L1 #L2 #H elim H -L1 -L2
+[ /2 width=3 by ex2_intro/
+| #I #L1 #L2 #V #_ #IHL12 #K1 #c #k #H
+ elim (drop_inv_O1_pair1 … H) -H * #Hm #HLK1
+ [ destruct
+ elim (IHL12 L1 c 0) -IHL12 // #X #HL12 #H
+ <(drop_inv_O2 … H) in HL12; -H /3 width=3 by lsubd_pair, drop_pair, ex2_intro/
+ | elim (IHL12 … HLK1) -L1 /3 width=3 by drop_drop_lt, ex2_intro/
+ ]
+| #L1 #L2 #W #V #d #HV #HW #_ #IHL12 #K1 #c #k #H
+ elim (drop_inv_O1_pair1 … H) -H * #Hm #HLK1
+ [ destruct
+ elim (IHL12 L1 c 0) -IHL12 // #X #HL12 #H
+ <(drop_inv_O2 … H) in HL12; -H /3 width=3 by lsubd_beta, drop_pair, ex2_intro/
+ | elim (IHL12 … HLK1) -L1 /3 width=3 by drop_drop_lt, ex2_intro/
+ ]
+]
+qed-.
+
+(* Note: the constant 0 cannot be generalized *)
+lemma lsubd_drop_O1_trans: ∀h,o,G,L1,L2. G ⊢ L1 ⫃▪[h, o] L2 →
+ ∀K2,c,k. ⬇[c, 0, k] L2 ≡ K2 →
+ ∃∃K1. G ⊢ K1 ⫃▪[h, o] K2 & ⬇[c, 0, k] L1 ≡ K1.
+#h #o #G #L1 #L2 #H elim H -L1 -L2
+[ /2 width=3 by ex2_intro/
+| #I #L1 #L2 #V #_ #IHL12 #K2 #c #k #H
+ elim (drop_inv_O1_pair1 … H) -H * #Hm #HLK2
+ [ destruct
+ elim (IHL12 L2 c 0) -IHL12 // #X #HL12 #H
+ <(drop_inv_O2 … H) in HL12; -H /3 width=3 by lsubd_pair, drop_pair, ex2_intro/
+ | elim (IHL12 … HLK2) -L2 /3 width=3 by drop_drop_lt, ex2_intro/
+ ]
+| #L1 #L2 #W #V #d #HV #HW #_ #IHL12 #K2 #c #k #H
+ elim (drop_inv_O1_pair1 … H) -H * #Hm #HLK2
+ [ destruct
+ elim (IHL12 L2 c 0) -IHL12 // #X #HL12 #H
+ <(drop_inv_O2 … H) in HL12; -H /3 width=3 by lsubd_beta, drop_pair, ex2_intro/
+ | elim (IHL12 … HLK2) -L2 /3 width=3 by drop_drop_lt, ex2_intro/
+ ]
+]
+qed-.
projects / helm.git / blobdiff