--- /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 "ground/arith/nat_plus.ma".
+(* * it should not depend on pr_isi *)
+include "ground/relocation/pr_isi_uni.ma".
+include "ground/relocation/pr_after_isi.ma".
+
+(* RELATIONAL COMPOSITION FOR PARTIAL RELOCATION MAPS ***********************)
+
+(* Constructions with pr_uni ************************************************)
+
+(*** after_uni *)
+lemma pr_after_uni (h1) (h2): 𝐮❨h1❩ ⊚ 𝐮❨h2❩ ≘ 𝐮❨h2+h1❩.
+#h1 @(nat_ind_succ … h1) -h1
+/3 width=5 by pr_after_isi_sn, pr_after_next, eq_f/
+qed.
+
+(*** after_uni_sn_pushs *)
+lemma pr_after_uni_sn_pushs (h):
+ ∀f. 𝐮❨h❩ ⊚ f ≘ ↑*[h]f.
+#h @(nat_ind_succ … h) -h
+/2 width=5 by pr_after_isi_sn, pr_after_next/
+qed.
+
+lemma pr_after_uni_isi_next (h1):
+ ∀f2. 𝐈❪f2❫ → 𝐮❨h1❩ ⊚ ↑f2 ≘ ↑𝐮❨h1❩.
+#h1 @(nat_ind_succ … h1) -h1
+/5 width=7 by pr_after_isi_dx, pr_after_eq_repl_back_sn, pr_after_next, pr_after_push, pr_isi_inv_eq_push/
+qed.
+
+lemma pr_after_uni_next_sn (h2):
+ ∀f1,f. ↑𝐮❨h2❩ ⊚ f1 ≘ f → 𝐮❨h2❩ ⊚ ↑f1 ≘ f.
+#h2 @(nat_ind_succ … h2) -h2
+[ #f1 #f #Hf
+ elim (pr_after_inv_next_sn … Hf) -Hf [2,3: // ] #g #Hg #H0 destruct
+ /4 width=7 by pr_after_isi_inv_sn, pr_after_isi_sn, pr_after_eq_repl_back, pr_eq_next/
+| #h2 #IH #f1 #f #Hf
+ elim (pr_after_inv_next_sn … Hf) -Hf [2,3: // ] #g #Hg #H0 destruct
+ /3 width=5 by pr_after_next/
+]
+qed.