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diff --git a/matita/matita/contribs/lambdadelta/static_2/s_computation/fqup_drops.ma b/matita/matita/contribs/lambdadelta/static_2/s_computation/fqup_drops.ma
new file mode 100644
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+(**************************************************************************)
+(*       ___                                                              *)
+(*      ||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 "static_2/relocation/drops.ma".
+include "static_2/s_computation/fqup.ma".
+
+(* PLUS-ITERATED SUPCLOSURE *************************************************)
+
+(* Properties with generic slicing for local environments *******************)
+
+lemma fqup_drops_succ: ∀b,G,K,T,i,L,U. ⬇*[↑i] L ≘ K → ⬆*[↑i] T ≘ U →
+                       ⦃G, L, U⦄ ⊐+[b] ⦃G, K, T⦄.
+#b #G #K #T #i elim i -i
+[ #L #U #HLK #HTU elim (drops_inv_succ … HLK) -HLK
+  #I #Y #HY #H destruct <(drops_fwd_isid … HY) -K //
+  /3 width=2 by fqu_fqup, fqu_drop/
+| #l #IH #L #U #HLK #HTU elim (drops_inv_succ … HLK) -HLK
+  #I #Y #HY #H destruct
+  elim (lifts_split_trans … HTU … (𝐔❴↑l❵) (𝐔❴1❵)) -HTU
+  /4 width=5 by fqup_strap2, fqu_drop/
+]
+qed.
+
+lemma fqup_drops_strap1: ∀b,G1,G2,L1,K1,K2,T1,T2,U1,i. ⬇*[i] L1 ≘ K1 → ⬆*[i] T1 ≘ U1 →
+                         ⦃G1, K1, T1⦄ ⊐[b] ⦃G2, K2, T2⦄ → ⦃G1, L1, U1⦄ ⊐+[b] ⦃G2, K2, T2⦄.
+#b #G1 #G2 #L1 #K1 #K2 #T1 #T2 #U1 *
+[ #HLK1 #HTU1 #HT12
+  >(drops_fwd_isid … HLK1) -L1 //
+  <(lifts_fwd_isid … HTU1) -U1 /2 width=1 by fqu_fqup/
+| /3 width=5 by fqup_strap1, fqup_drops_succ/
+]
+qed-.
+
+lemma fqup_lref: ∀b,I,G,L,K,V,i. ⬇*[i] L ≘ K.ⓑ{I}V → ⦃G, L, #i⦄ ⊐+[b] ⦃G, K, V⦄.
+/2 width=6 by fqup_drops_strap1/ qed.