--- /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_pat_tls.ma".
+include "ground/relocation/pr_isf_tls.ma".
+include "ground/relocation/pr_ist_tls.ma".
+include "ground/relocation/pr_coafter_nat_tls.ma".
+include "ground/relocation/pr_coafter_isi.ma".
+
+(* RELATIONAL CO-COMPOSITION FOR PARTIAL RELOCATION MAPS ********************)
+
+(*** H_coafter_isfin2_fwd *)
+definition H_pr_coafter_des_ist_isf: predicate pr_map â
+ Îťf1. âf2. đ
âŞf2⍠â đâŞf1⍠â âf. f1 ~â f2 â f â đ
âŞfâŤ.
+
+(* Destructions with pr_ist and pr_isf **************************************)
+
+(*** coafter_isfin2_fwd_O_aux *)
+fact pr_coafter_des_ist_isf_unit_aux:
+ âf1. @âŞđ, f1⍠â đ â H_pr_coafter_des_ist_isf f1.
+#f1 #Hf1 #f2 #H
+generalize in match Hf1; generalize in match f1; -f1
+@(pr_isf_ind ⌠H) -f2
+[ /3 width=4 by pr_coafter_isi_inv_dx, pr_isf_isi/ ]
+#f2 #_ #IH #f1 #H #Hf1 #f #Hf
+elim (pr_pat_inv_unit_bi ⌠H) -H [ |*: // ] #g1 #H1
+lapply (pr_ist_inv_push ⌠Hf1 ⌠H1) -Hf1 #Hg1
+elim (Hg1 (đ)) #n #Hn
+[ elim (pr_coafter_inv_push_bi ⌠Hf) | elim (pr_coafter_inv_push_next ⌠Hf)
+] -Hf [1,6: |*: // ] #g #Hg #H0 destruct
+/5 width=6 by pr_isf_next, pr_isf_push, pr_isf_inv_tls, pr_ist_tls, pr_pat_unit_succ_tls, pr_coafter_tls_sn_tls/
+qed-.
+
+(*** coafter_isfin2_fwd_aux *)
+fact pr_coafter_des_ist_isf_aux:
+ (âf1. @âŞđ, f1⍠â đ â H_pr_coafter_des_ist_isf f1) â
+ âi2,f1. @âŞđ, f1⍠â i2 â H_pr_coafter_des_ist_isf f1.
+#H0 #i2 elim i2 -i2 /2 width=1 by/ -H0
+#i2 #IH #f1 #H1f1 #f2 #Hf2 #H2f1 #f #Hf
+elim (pr_pat_inv_unit_succ ⌠H1f1) -H1f1 [ |*: // ] #g1 #Hg1 #H1
+elim (pr_coafter_inv_next_sn ⌠Hf ⌠H1) -Hf #g #Hg #H0
+lapply (IH ⌠Hg1 ⌠Hg) -i2 -Hg
+/2 width=4 by pr_ist_inv_next, pr_isf_push/ (* * full auto fails *)
+qed-.
+
+(*** coafter_isfin2_fwd *)
+lemma pr_coafter_des_ist_isf: âf1. H_pr_coafter_des_ist_isf f1.
+#f1 #f2 #Hf2 #Hf1 cases (Hf1 (đ))
+/3 width=7 by pr_coafter_des_ist_isf_aux, pr_coafter_des_ist_isf_unit_aux/
+qed-.