--- /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_isi.ma".
+include "ground/relocation/pr_after_after.ma".
+
+(* RELATIONAL COMPOSITION FOR PARTIAL RELOCATION MAPS ***********************)
+
+(* Constructions with pr_isi ************************************************)
+
+(*** after_isid_sn *)
+corec lemma pr_after_isi_sn:
+ âf1. đâŞf1⍠â âf2. f1 â f2 â f2.
+#f1 * -f1
+#f1 #g1 #Hf1 #H1 #f2 cases (pr_map_split_tl f2) #H2
+/3 width=7 by pr_after_push, pr_after_refl/
+qed.
+
+(*** after_isid_dx *)
+corec lemma pr_after_isi_dx:
+ âf2. đâŞf2⍠â âf1. f1 â f2 â f1.
+#f2 * -f2
+#f2 #g2 #Hf2 #H2 #f1 cases (pr_map_split_tl f1) #H1
+[ /3 width=7 by pr_after_refl/
+| @(pr_after_next ⌠H1 H1) /3 width=3 by pr_isi_push/
+]
+qed.
+
+(* Destructions with pr_isi *************************************************)
+
+(*** after_isid_inv_sn *)
+lemma pr_after_isi_inv_sn:
+ âf1,f2,f. f1 â f2 â f â đâŞf1⍠â f2 ⥠f.
+/3 width=6 by pr_after_isi_sn, pr_after_mono/ qed-.
+
+(*** after_isid_inv_dx *)
+lemma pr_after_isi_inv_dx:
+ âf1,f2,f. f1 â f2 â f â đâŞf2⍠â f1 ⥠f.
+/3 width=6 by pr_after_isi_dx, pr_after_mono/ qed-.
+
+(*** after_fwd_isid1 *)
+corec lemma pr_after_des_isi_sn:
+ âf1,f2,f. f1 â f2 â f â đâŞf⍠â đâŞf1âŤ.
+#f1 #f2 #f * -f1 -f2 -f
+#f1 #f2 #f #g1 [1,2: #g2 ] #g #Hf #H1 [1,2: #H2 ] #H0 #H
+[ /4 width=6 by pr_isi_inv_push, pr_isi_push/ ]
+cases (pr_isi_inv_next ⌠H ⌠H0)
+qed-.
+
+(*** after_fwd_isid2 *)
+corec lemma pr_after_des_isi_dx:
+ âf1,f2,f. f1 â f2 â f â đâŞf⍠â đâŞf2âŤ.
+#f1 #f2 #f * -f1 -f2 -f
+#f1 #f2 #f #g1 [1,2: #g2 ] #g #Hf #H1 [1,2: #H2 ] #H0 #H
+[ /4 width=6 by pr_isi_inv_push, pr_isi_push/ ]
+cases (pr_isi_inv_next ⌠H ⌠H0)
+qed-.
+
+(*** after_inv_isid3 *)
+lemma pr_after_inv_isi:
+ âf1,f2,f. f1 â f2 â f â đâŞf⍠â đâŞf1⍠⧠đâŞf2âŤ.
+/3 width=4 by pr_after_des_isi_dx, pr_after_des_isi_sn, conj/ qed-.