--- /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/relocation/pr_tls.ma".
+include "ground/relocation/pr_pat.ma".
+include "ground/relocation/pr_after.ma".
+
+(* RELATIONAL COMPOSITION FOR PARTIAL RELOCATION MAPS ***********************)
+
+(* Constructions with pr_pat and pr_tls *************************************)
+
+(* Note: this requires ↑ on first n *)
+(*** after_tls *)
+lemma pr_after_tls_sn_tls (n):
+ ∀f1,f2,f. @❪𝟏, f1❫ ≘ ↑n →
+ f1 ⊚ f2 ≘ f → ⫰*[n]f1 ⊚ f2 ≘ ⫰*[n]f.
+#n @(nat_ind_succ … n) -n //
+#n #IH #f1 #f2 #f #Hf1 #Hf
+cases (pr_pat_inv_unit_succ … Hf1) -Hf1 [ |*: // ] #g1 #Hg1 #H1
+cases (pr_after_inv_next_sn … Hf … H1) -Hf #g #Hg #H0 destruct
+<pr_tls_swap <pr_tls_swap /2 width=1 by/
+qed.