X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Flib%2Flambda-delta%2Fsubstitution%2Flift.ma;h=60b1b62e74481cbe2876661f8ac448bd59423995;hb=2d7c5c2bc32162612138e329a48c8108e010334d;hp=181642504a8fdcff1c642980c43e26b59f063b94;hpb=78b1c68fca5f15000588a1e091149a188831977e;p=helm.git

diff --git a/matita/matita/lib/lambda-delta/substitution/lift.ma b/matita/matita/lib/lambda-delta/substitution/lift.ma
index 181642504..60b1b62e7 100644
--- a/matita/matita/lib/lambda-delta/substitution/lift.ma
+++ b/matita/matita/lib/lambda-delta/substitution/lift.ma
@@ -9,17 +9,20 @@
      \ /
       V_______________________________________________________________ *)
 
-include "lambda-delta/language/term.ma".
+include "lambda-delta/syntax/term.ma".
 
 (* RELOCATION ***************************************************************)
 
 inductive lift: term → nat → nat → term → Prop ≝
-   | lift_sort   : ∀k,d,e. lift (⋆k) d e (⋆k)
-   | lift_lref_lt: ∀i,d,e. i < d → lift (#i) d e (#i)
-   | lift_lref_ge: ∀i,d,e. d ≤ i → lift (#i) d e (#(i + e))
-   | lift_con2   : ∀I,V1,V2,T1,T2,d,e.
-                   lift V1 d e V2 → lift T1 (d + 1) e T2 →
-                   lift (♭I V1. T1) d e (♭I V2. T2)
+| lift_sort   : ∀k,d,e. lift (⋆k) d e (⋆k)
+| lift_lref_lt: ∀i,d,e. i < d → lift (#i) d e (#i)
+| lift_lref_ge: ∀i,d,e. d ≤ i → lift (#i) d e (#(i + e))
+| lift_bind   : ∀I,V1,V2,T1,T2,d,e.
+                lift V1 d e V2 → lift T1 (d + 1) e T2 →
+                lift (𝕓{I} V1. T1) d e (𝕓{I} V2. T2)
+| lift_flat   : ∀I,V1,V2,T1,T2,d,e.
+                lift V1 d e V2 → lift T1 d e T2 →
+                lift (𝕗{I} V1. T1) d e (𝕗{I} V2. T2)
 .
 
 interpretation "relocation" 'RLift T1 d e T2 = (lift T1 d e T2).
@@ -32,11 +35,78 @@ qed.
 
 (* The basic inversion lemmas ***********************************************)
 
+lemma lift_inv_sort1_aux: ∀d,e,T1,T2. ↑[d,e] T1 ≡ T2 → ∀k. T1 = ⋆k → T2 = ⋆k.
+#d #e #T1 #T2 #H elim H -H d e T1 T2 //
+[ #i #d #e #_ #k #H destruct
+| #I #V1 #V2 #T1 #T2 #d #e #_ #_ #_ #_ #k #H destruct
+| #I #V1 #V2 #T1 #T2 #d #e #_ #_ #_ #_ #k #H destruct
+]
+qed.
+
+lemma lift_inv_sort1: ∀d,e,T2,k. ↑[d,e] ⋆k ≡ T2 → T2 = ⋆k.
+#d #e #T2 #k #H lapply (lift_inv_sort1_aux … H) /2/
+qed.
+
+lemma lift_inv_lref1_aux: ∀d,e,T1,T2. ↑[d,e] T1 ≡ T2 → ∀i. T1 = #i →
+                          (i < d ∧ T2 = #i) ∨ (d ≤ i ∧ T2 = #(i + e)).
+#d #e #T1 #T2 #H elim H -H d e T1 T2
+[ #k #d #e #i #H destruct
+| #j #d #e #Hj #i #Hi destruct /3/
+| #j #d #e #Hj #i #Hi destruct /3/
+| #I #V1 #V2 #T1 #T2 #d #e #_ #_ #_ #_ #i #H destruct
+| #I #V1 #V2 #T1 #T2 #d #e #_ #_ #_ #_ #i #H destruct
+]
+qed.
+
+lemma lift_inv_lref1: ∀d,e,T2,i. ↑[d,e] #i ≡ T2 →
+                      (i < d ∧ T2 = #i) ∨ (d ≤ i ∧ T2 = #(i + e)).
+#d #e #T2 #i #H lapply (lift_inv_lref1_aux … H) /2/
+qed.
+
+lemma lift_inv_bind1_aux: ∀d,e,T1,T2. ↑[d,e] T1 ≡ T2 →
+                          ∀I,V1,U1. T1 = 𝕓{I} V1.U1 →
+                          ∃∃V2,U2. ↑[d,e] V1 ≡ V2 & ↑[d+1,e] U1 ≡ U2 &
+                                   T2 = 𝕓{I} V2. U2.
+#d #e #T1 #T2 #H elim H -H d e T1 T2
+[ #k #d #e #I #V1 #U1 #H destruct
+| #i #d #e #_ #I #V1 #U1 #H destruct
+| #i #d #e #_ #I #V1 #U1 #H destruct
+| #J #W1 #W2 #T1 #T2 #d #e #HW #HT #_ #_ #I #V1 #U1 #H destruct /2 width=5/
+| #J #W1 #W2 #T1 #T2 #d #e #HW #HT #_ #_ #I #V1 #U1 #H destruct
+]
+qed.
+
+lemma lift_inv_bind1: ∀d,e,T2,I,V1,U1. ↑[d,e] 𝕓{I} V1. U1 ≡ T2 →
+                      ∃∃V2,U2. ↑[d,e] V1 ≡ V2 & ↑[d+1,e] U1 ≡ U2 &
+                               T2 = 𝕓{I} V2. U2.
+#d #e #T2 #I #V1 #U1 #H lapply (lift_inv_bind1_aux … H) /2/
+qed.
+
+lemma lift_inv_flat1_aux: ∀d,e,T1,T2. ↑[d,e] T1 ≡ T2 →
+                          ∀I,V1,U1. T1 = 𝕗{I} V1.U1 →
+                          ∃∃V2,U2. ↑[d,e] V1 ≡ V2 & ↑[d,e] U1 ≡ U2 &
+                                   T2 = 𝕗{I} V2. U2.
+#d #e #T1 #T2 #H elim H -H d e T1 T2
+[ #k #d #e #I #V1 #U1 #H destruct
+| #i #d #e #_ #I #V1 #U1 #H destruct
+| #i #d #e #_ #I #V1 #U1 #H destruct
+| #J #W1 #W2 #T1 #T2 #d #e #HW #HT #_ #_ #I #V1 #U1 #H destruct
+| #J #W1 #W2 #T1 #T2 #d #e #HW #HT #_ #_ #I #V1 #U1 #H destruct /2 width=5/
+]
+qed.
+
+lemma lift_inv_flat1: ∀d,e,T2,I,V1,U1. ↑[d,e] 𝕗{I} V1. U1 ≡ T2 →
+                      ∃∃V2,U2. ↑[d,e] V1 ≡ V2 & ↑[d,e] U1 ≡ U2 &
+                               T2 = 𝕗{I} V2. U2.
+#d #e #T2 #I #V1 #U1 #H lapply (lift_inv_flat1_aux … H) /2/
+qed.
+
 lemma lift_inv_sort2_aux: ∀d,e,T1,T2. ↑[d,e] T1 ≡ T2 → ∀k. T2 = ⋆k → T1 = ⋆k.
 #d #e #T1 #T2 #H elim H -H d e T1 T2 //
-   [ #i #d #e #_ #k #H destruct
-   | #I #V1 #V2 #T1 #T2 #d #e #_ #_ #_ #_ #k #H destruct
-   ]
+[ #i #d #e #_ #k #H destruct
+| #I #V1 #V2 #T1 #T2 #d #e #_ #_ #_ #_ #k #H destruct
+| #I #V1 #V2 #T1 #T2 #d #e #_ #_ #_ #_ #k #H destruct
+]
 qed.
 
 lemma lift_inv_sort2: ∀d,e,T1,k. ↑[d,e] T1 ≡ ⋆k → T1 = ⋆k.
@@ -46,11 +116,12 @@ qed.
 lemma lift_inv_lref2_aux: ∀d,e,T1,T2. ↑[d,e] T1 ≡ T2 → ∀i. T2 = #i →
                           (i < d ∧ T1 = #i) ∨ (d + e ≤ i ∧ T1 = #(i - e)).
 #d #e #T1 #T2 #H elim H -H d e T1 T2
-   [ #k #d #e #i #H destruct
-   | #j #d #e #Hj #i #Hi destruct /3/
-   | #j #d #e #Hj #i #Hi destruct <minus_plus_m_m /4/
-   | #I #V1 #V2 #T1 #T2 #d #e #_ #_ #_ #_ #i #H destruct
-   ]
+[ #k #d #e #i #H destruct
+| #j #d #e #Hj #i #Hi destruct /3/
+| #j #d #e #Hj #i #Hi destruct <minus_plus_m_m /4/
+| #I #V1 #V2 #T1 #T2 #d #e #_ #_ #_ #_ #i #H destruct
+| #I #V1 #V2 #T1 #T2 #d #e #_ #_ #_ #_ #i #H destruct
+]
 qed.
 
 lemma lift_inv_lref2: ∀d,e,T1,i. ↑[d,e] T1 ≡ #i →
@@ -58,79 +129,138 @@ lemma lift_inv_lref2: ∀d,e,T1,i. ↑[d,e] T1 ≡ #i →
 #d #e #T1 #i #H lapply (lift_inv_lref2_aux … H) /2/
 qed.
 
-lemma lift_inv_con22_aux: ∀d,e,T1,T2. ↑[d,e] T1 ≡ T2 →
-                          ∀I,V2,U2. T2 = ♭I V2.U2 →
-                          ∃V1,U1. ↑[d,e] V1 ≡ V2 ∧ ↑[d+1,e] U1 ≡ U2 ∧
-                                  T1 = ♭I V1.U1.
+lemma lift_inv_bind2_aux: ∀d,e,T1,T2. ↑[d,e] T1 ≡ T2 →
+                          ∀I,V2,U2. T2 = 𝕓{I} V2.U2 →
+                          ∃∃V1,U1. ↑[d,e] V1 ≡ V2 & ↑[d+1,e] U1 ≡ U2 &
+                                   T1 = 𝕓{I} V1. U1.
 #d #e #T1 #T2 #H elim H -H d e T1 T2
-   [ #k #d #e #I #V2 #U2 #H destruct
-   | #i #d #e #_ #I #V2 #U2 #H destruct
-   | #i #d #e #_ #I #V2 #U2 #H destruct
-   | #J #W1 #W2 #T1 #T2 #d #e #HW #HT #_ #_ #I #V2 #U2 #H destruct /5/
+[ #k #d #e #I #V2 #U2 #H destruct
+| #i #d #e #_ #I #V2 #U2 #H destruct
+| #i #d #e #_ #I #V2 #U2 #H destruct
+| #J #W1 #W2 #T1 #T2 #d #e #HW #HT #_ #_ #I #V2 #U2 #H destruct /2 width=5/
+| #J #W1 #W2 #T1 #T2 #d #e #HW #HT #_ #_ #I #V2 #U2 #H destruct
+]
 qed.
 
-lemma lift_inv_con22: ∀d,e,T1,I,V2,U2. ↑[d,e] T1 ≡  ♭I V2. U2 →
-                      ∃V1,U1. ↑[d,e] V1 ≡ V2 ∧ ↑[d+1,e] U1 ≡ U2 ∧
-                              T1 = ♭I V1. U1.
-#d #e #T1 #I #V2 #U2 #H lapply (lift_inv_con22_aux … H) /2/
+lemma lift_inv_bind2: ∀d,e,T1,I,V2,U2. ↑[d,e] T1 ≡  𝕓{I} V2. U2 →
+                      ∃∃V1,U1. ↑[d,e] V1 ≡ V2 & ↑[d+1,e] U1 ≡ U2 &
+                               T1 = 𝕓{I} V1. U1.
+#d #e #T1 #I #V2 #U2 #H lapply (lift_inv_bind2_aux … H) /2/
+qed.
+
+lemma lift_inv_flat2_aux: ∀d,e,T1,T2. ↑[d,e] T1 ≡ T2 →
+                          ∀I,V2,U2. T2 = 𝕗{I} V2.U2 →
+                          ∃∃V1,U1. ↑[d,e] V1 ≡ V2 & ↑[d,e] U1 ≡ U2 &
+                                   T1 = 𝕗{I} V1. U1.
+#d #e #T1 #T2 #H elim H -H d e T1 T2
+[ #k #d #e #I #V2 #U2 #H destruct
+| #i #d #e #_ #I #V2 #U2 #H destruct
+| #i #d #e #_ #I #V2 #U2 #H destruct
+| #J #W1 #W2 #T1 #T2 #d #e #HW #HT #_ #_ #I #V2 #U2 #H destruct
+| #J #W1 #W2 #T1 #T2 #d #e #HW #HT #_ #_ #I #V2 #U2 #H destruct /2 width = 5/
+]
+qed.
+
+lemma lift_inv_flat2: ∀d,e,T1,I,V2,U2. ↑[d,e] T1 ≡  𝕗{I} V2. U2 →
+                      ∃∃V1,U1. ↑[d,e] V1 ≡ V2 & ↑[d,e] U1 ≡ U2 &
+                               T1 = 𝕗{I} V1. U1.
+#d #e #T1 #I #V2 #U2 #H lapply (lift_inv_flat2_aux … H) /2/
 qed.
 
 (* the main properies *******************************************************)
 
-theorem lift_trans_rev: ∀d1,e1,T1,T. ↑[d1,e1] T1 ≡ T →
-                        ∀d2,e2,T2. ↑[d2 + e1, e2] T2 ≡ T →
-                        d1 ≤ d2 →
-                        ∃T0. ↑[d1, e1] T0 ≡ T2 ∧ ↑[d2, e2] T0 ≡ T1.
+axiom lift_total: ∀d,e,T1. ∃T2. ↑[d,e] T1 ≡ T2.
+
+axiom lift_mono:  ∀d,e,T,U1. ↑[d,e] T ≡ U1 → ∀U2. ↑[d,e] T ≡ U2 → U1 = U2.
+
+theorem lift_conf_rev: ∀d1,e1,T1,T. ↑[d1,e1] T1 ≡ T →
+                       ∀d2,e2,T2. ↑[d2 + e1, e2] T2 ≡ T →
+                       d1 ≤ d2 →
+                       ∃∃T0. ↑[d1, e1] T0 ≡ T2 & ↑[d2, e2] T0 ≡ T1.
 #d1 #e1 #T1 #T #H elim H -H d1 e1 T1 T
-   [ #k #d1 #e1 #d2 #e2 #T2 #Hk #Hd12
-     lapply (lift_inv_sort2 … Hk) -Hk #Hk destruct -T2 /3/
-   | #i #d1 #e1 #Hid1 #d2 #e2 #T2 #Hi #Hd12
-     lapply (lift_inv_lref2 … Hi) -Hi #H
-     elim H -H #H elim H -H #Hid2 #Hi (**) (* decompose*)
-     destruct -T2
-     [ -Hid2 /5/ (**) (* /4/ *)
-     | elim (lt_false d1 ?)
-       @(le_to_lt_to_lt … Hd12) -Hd12 @(le_to_lt_to_lt … Hid1) -Hid1 /2/
-     ]
-   | #i #d1 #e1 #Hid1 #d2 #e2 #T2 #Hi #Hd12
-     lapply (lift_inv_lref2 … Hi) -Hi #H
-     elim H -H #H elim H -H #Hid2 #Hi (**) (* decompose*)
-     destruct -T2
-     [ -Hd12; lapply (lt_plus_to_lt_l … Hid2) -Hid2 #Hid2 /4/
-     | -Hid1; lapply (arith1 … Hid2) -Hid2 #Hid2
-       @(ex_intro … #(i - e2)) @conj
-       [ >le_plus_minus_comm [ @lift_lref_ge @(transitive_le … Hd12) -Hd12 /2/ | -Hd12 /2/ ]
-       | -Hd12 >(plus_minus_m_m i e2) in ⊢ (? ? ? ? %) /3/
-       ]
-     ]
-   | #I #W1 #W #U1 #U #d1 #e1 #_ #_ #IHW #IHU #d2 #e2 #T2 #H #Hd12
-     lapply (lift_inv_con22 … H) -H #H
-     elim H -H #W2 #H elim H -H #U2 #H elim H -H #H elim H -H #HW2 #HU2 #H (**) (* decompose*)
-     destruct -T2;
-     elim (IHW … HW2 ?) // -IHW HW2 #W0 #H
-     elim H -H #HW2 #HW1 (**) (* decompose*)
-     >plus_plus_comm_23 in HU2 #HU2 elim (IHU … HU2 ?) /2/ -IHU HU2 Hd12 #U0 #H
-     elim H -H #HU2 #HU1 (**) (* decompose*)
-     @(ex_intro … ♭I W0. U0) /3/ (**) (* /4/ *)
-   ]
+[ #k #d1 #e1 #d2 #e2 #T2 #Hk #Hd12
+  lapply (lift_inv_sort2 … Hk) -Hk #Hk destruct -T2 /3/
+| #i #d1 #e1 #Hid1 #d2 #e2 #T2 #Hi #Hd12
+  lapply (lift_inv_lref2 … Hi) -Hi * * #Hid2 #H destruct -T2
+  [ -Hid2 /4/
+  | elim (lt_false d1 ?)
+    @(le_to_lt_to_lt … Hd12) -Hd12 @(le_to_lt_to_lt … Hid1) -Hid1 /2/
+  ]
+| #i #d1 #e1 #Hid1 #d2 #e2 #T2 #Hi #Hd12
+  lapply (lift_inv_lref2 … Hi) -Hi * * #Hid2 #H destruct -T2
+  [ -Hd12; lapply (lt_plus_to_lt_l … Hid2) -Hid2 #Hid2 /3/
+  | -Hid1; lapply (arith1 … Hid2) -Hid2 #Hid2
+    @(ex2_1_intro … #(i - e2))
+    [ >le_plus_minus_comm [ @lift_lref_ge @(transitive_le … Hd12) -Hd12 /2/ | -Hd12 /2/ ]
+    | -Hd12 >(plus_minus_m_m i e2) in ⊢ (? ? ? ? %) /3/
+    ]
+  ]
+| #I #W1 #W #U1 #U #d1 #e1 #_ #_ #IHW #IHU #d2 #e2 #T2 #H #Hd12
+  lapply (lift_inv_bind2 … H) -H * #W2 #U2 #HW2 #HU2 #H destruct -T2;
+  elim (IHW … HW2 ?) // -IHW HW2 #W0 #HW2 #HW1
+  >plus_plus_comm_23 in HU2 #HU2 elim (IHU … HU2 ?) /3 width = 5/
+| #I #W1 #W #U1 #U #d1 #e1 #_ #_ #IHW #IHU #d2 #e2 #T2 #H #Hd12
+  lapply (lift_inv_flat2 … H) -H * #W2 #U2 #HW2 #HU2 #H destruct -T2;
+  elim (IHW … HW2 ?) // -IHW HW2 #W0 #HW2 #HW1
+  elim (IHU … HU2 ?) /3 width = 5/
+]
 qed.
 
 theorem lift_free: ∀d1,e2,T1,T2. ↑[d1, e2] T1 ≡ T2 → ∀d2,e1.
                                  d1 ≤ d2 → d2 ≤ d1 + e1 → e1 ≤ e2 →
-                                 ∃T. ↑[d1, e1] T1 ≡ T ∧ ↑[d2, e2 - e1] T ≡ T2.
+                                 ∃∃T. ↑[d1, e1] T1 ≡ T & ↑[d2, e2 - e1] T ≡ T2.
 #d1 #e2 #T1 #T2 #H elim H -H d1 e2 T1 T2
-   [ /3/
-   | #i #d1 #e2 #Hid1 #d2 #e1 #Hd12 #_ #_
-     lapply (lt_to_le_to_lt … Hid1 Hd12) -Hd12 #Hid2 /4/
-   | #i #d1 #e2 #Hid1 #d2 #e1 #_ #Hd21 #He12
-     lapply (transitive_le …(i+e1) Hd21 ?) /2/ -Hd21 #Hd21
-     <(plus_plus_minus_m_m e1 e2 i) //
-     @(ex_intro … #(i+e1)) /3/ (**) (* /4/ *)
-   | #I #V1 #V2 #T1 #T2 #d1 #e2 #_ #_ #IHV #IHT #d2 #e1 #Hd12 #Hd21 #He12
-     elim (IHV … Hd12 Hd21 He12) -IHV #V0 #H
-     elim H -H #HV0a #HV0b (**) (* decompose *)
-     elim (IHT (d2+1) … ? ? He12) /2/ -IHT Hd12 Hd21 He12 #T0 #H
-     elim H -H #HT0a #HT0b (**) (* decompose *)
-     @(ex_intro … ♭I V0.T0) /3/ (**) (* /4/ *)
-   ]
+[ /3/
+| #i #d1 #e2 #Hid1 #d2 #e1 #Hd12 #_ #_
+  lapply (lt_to_le_to_lt … Hid1 Hd12) -Hd12 #Hid2 /4/
+| #i #d1 #e2 #Hid1 #d2 #e1 #_ #Hd21 #He12
+  lapply (transitive_le …(i+e1) Hd21 ?) /2/ -Hd21 #Hd21
+  <(plus_plus_minus_m_m e1 e2 i) /3/
+| #I #V1 #V2 #T1 #T2 #d1 #e2 #_ #_ #IHV #IHT #d2 #e1 #Hd12 #Hd21 #He12
+  elim (IHV … Hd12 Hd21 He12) -IHV #V0 #HV0a #HV0b
+  elim (IHT (d2+1) … ? ? He12) /3 width = 5/
+| #I #V1 #V2 #T1 #T2 #d1 #e2 #_ #_ #IHV #IHT #d2 #e1 #Hd12 #Hd21 #He12
+  elim (IHV … Hd12 Hd21 He12) -IHV #V0 #HV0a #HV0b
+  elim (IHT d2 … ? ? He12) /3 width = 5/
+]
 qed.
+
+theorem lift_trans: ∀d1,e1,T1,T. ↑[d1, e1] T1 ≡ T →
+                    ∀d2,e2,T2. ↑[d2, e2] T ≡ T2 →
+                    d1 ≤ d2 → d2 ≤ d1 + e1 → ↑[d1, e1 + e2] T1 ≡ T2.
+#d1 #e1 #T1 #T #H elim H -d1 e1 T1 T
+[ #k #d1 #e1 #d2 #e2 #T2 #HT2 #_ #_
+  >(lift_inv_sort1 … HT2) -HT2 //
+| #i #d1 #e1 #Hid1 #d2 #e2 #T2 #HT2 #Hd12 #_
+  lapply (lift_inv_lref1 … HT2) -HT2 * * #Hid2 #H destruct -T2
+  [ -Hd12 Hid2 /2/
+  | lapply (le_to_lt_to_lt … d1 Hid2 ?) // -Hid1 Hid2 #Hd21
+    lapply (le_to_lt_to_lt … d1 Hd12 ?) // -Hd12 Hd21 #Hd11
+    elim (lt_false … Hd11)
+  ]
+| #i #d1 #e1 #Hid1 #d2 #e2 #T2 #HT2 #_ #Hd21
+  lapply (lift_inv_lref1 … HT2) -HT2 * * #Hid2 #H destruct -T2
+  [ lapply (lt_to_le_to_lt … (d1+e1) Hid2 ?) // -Hid2 Hd21 #H
+    lapply (lt_plus_to_lt_l … H) -H #H
+    lapply (le_to_lt_to_lt … d1 Hid1 ?) // -Hid1 H #Hd11
+    elim (lt_false … Hd11)
+  | -Hd21 Hid2 /2/
+  ]
+| #I #V1 #V2 #T1 #T2 #d1 #e1 #_ #_ #IHV12 #IHT12 #d2 #e2 #X #HX #Hd12 #Hd21
+  lapply (lift_inv_bind1 … HX) -HX * #V0 #T0 #HV20 #HT20 #HX destruct -X;
+  lapply (IHV12 … HV20 ? ?) // -IHV12 HV20 #HV10
+  lapply (IHT12 … HT20 ? ?) /2/
+| #I #V1 #V2 #T1 #T2 #d1 #e1 #_ #_ #IHV12 #IHT12 #d2 #e2 #X #HX #Hd12 #Hd21
+  lapply (lift_inv_flat1 … HX) -HX * #V0 #T0 #HV20 #HT20 #HX destruct -X;
+  lapply (IHV12 … HV20 ? ?) // -IHV12 HV20 #HV10
+  lapply (IHT12 … HT20 ? ?) /2/
+]
+qed.
+
+axiom lift_trans_le: ∀d1,e1,T1,T. ↑[d1, e1] T1 ≡ T →
+                     ∀d2,e2,T2. ↑[d2, e2] T ≡ T2 → d2 ≤ d1 →
+                     ∃∃T0. ↑[d2, e2] T1 ≡ T0 & ↑[d1 + e2, e1] T0 ≡ T2.
+
+axiom lift_trans_ge: ∀d1,e1,T1,T. ↑[d1, e1] T1 ≡ T →
+                     ∀d2,e2,T2. ↑[d2, e2] T ≡ T2 → d1 + e1 ≤ d2 →
+                     ∃∃T0. ↑[d2 - e1, e2] T1 ≡ T0 & ↑[d1, e1] T0 ≡ T2.