+(* Basic_1: was: lift1_sort *)
+lemma lifts_inv_sort1: ∀T2,k,des. ⇧*[des] ⋆k ≡ T2 → T2 = ⋆k.
+#T2 #k #des elim des -des
+[ #H <(lifts_inv_nil … H) -H //
+| #d #e #des #IH #H
+ elim (lifts_inv_cons … H) -H #X #H
+ >(lift_inv_sort1 … H) -H /2 width=1/
+]
+qed-.
+
+(* Basic_1: was: lift1_lref *)
+lemma lifts_inv_lref1: ∀T2,des,i1. ⇧*[des] #i1 ≡ T2 →
+ ∃∃i2. @[i1] des ≡ i2 & T2 = #i2.
+#T2 #des elim des -des
+[ #i1 #H <(lifts_inv_nil … H) -H /2 width=3/
+| #d #e #des #IH #i1 #H
+ elim (lifts_inv_cons … H) -H #X #H1 #H2
+ elim (lift_inv_lref1 … H1) -H1 * #Hdi1 #H destruct
+ elim (IH … H2) -IH -H2 /3 width=3/
+]
+qed-.
+
+lemma lifts_inv_gref1: ∀T2,p,des. ⇧*[des] §p ≡ T2 → T2 = §p.
+#T2 #p #des elim des -des
+[ #H <(lifts_inv_nil … H) -H //
+| #d #e #des #IH #H
+ elim (lifts_inv_cons … H) -H #X #H
+ >(lift_inv_gref1 … H) -H /2 width=1/
+]
+qed-.
+
+(* Basic_1: was: lift1_bind *)