--- /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/xoa/ex_3_1.ma".
+include "ground/xoa/ex_4_2.ma".
+include "ground/arith/nat_plus.ma".
+include "ground/arith/nat_le_max.ma".
+include "ground/relocation/pr_fcla_eq.ma".
+include "ground/relocation/pr_sor_isi.ma".
+
+(* RELATIONAL UNION FOR PARTIAL RELOCATION MAPS *****************************)
+
+(* Constructions with pr_fcla ***********************************************)
+
+(*** sor_fcla_ex *)
+lemma pr_sor_fcla_bi:
+ âf1,n1. đâŞf1⍠â n1 â âf2,n2. đâŞf2⍠â n2 â
+ ââf,n. f1 â f2 â f & đâŞf⍠â n & (n1 ⨠n2) ⤠n & n ⤠n1 + n2.
+#f1 #n1 #Hf1 elim Hf1 -f1 -n1 /3 width=6 by pr_sor_isi_sn, ex4_2_intro/
+#f1 #n1 #Hf1 #IH #f2 #n2 * -f2 -n2 /3 width=6 by pr_fcla_push, pr_fcla_next, ex4_2_intro, pr_sor_isi_dx/
+#f2 #n2 #Hf2 elim (IH ⌠Hf2) -IH -Hf2 -Hf1 [2,4: #f #n <nplus_succ_dx ] (* * full auto fails *)
+[ /3 width=7 by pr_fcla_next, pr_sor_push_next, nle_max_sn_succ_dx, nle_succ_bi, ex4_2_intro/
+| /4 width=7 by pr_fcla_next, pr_sor_next_bi, nle_succ_dx, nle_succ_bi, ex4_2_intro/
+| /3 width=7 by pr_fcla_push, pr_sor_push_bi, ex4_2_intro/
+| /3 width=7 by pr_fcla_next, pr_sor_next_push, nle_max_sn_succ_sn, nle_succ_bi, ex4_2_intro/
+]
+qed-.
+
+(* Destructions with pr_fcla ************************************************)
+
+(*** sor_fcla *)
+lemma pr_sor_inv_fcla_bi:
+ âf1,n1. đâŞf1⍠â n1 â âf2,n2. đâŞf2⍠â n2 â âf. f1 â f2 â f â
+ âân. đâŞf⍠â n & (n1 ⨠n2) ⤠n & n ⤠n1 + n2.
+#f1 #n1 #Hf1 #f2 #n2 #Hf2 #f #Hf elim (pr_sor_fcla_bi ⌠Hf1 ⌠Hf2) -Hf1 -Hf2
+/4 width=6 by pr_sor_mono, pr_fcla_eq_repl_back, ex3_intro/
+qed-.
+
+(* Destructions with pr_fcla ************************************************)
+
+(*** sor_fwd_fcla_sn_ex *)
+lemma pr_sor_des_fcla_sn:
+ âf,n. đâŞf⍠â n â âf1,f2. f1 â f2 â f â
+ âân1. đâŞf1⍠â n1 & n1 ⤠n.
+#f #n #H elim H -f -n
+[ /4 width=4 by pr_sor_des_isi_sn, pr_fcla_isi, ex2_intro/
+| #f #n #_ #IH #f1 #f2 #H
+ elim (pr_sor_inv_push ⌠H) -H [ |*: // ] #g1 #g2 #Hf #H1 #H2 destruct
+ elim (IH ⌠Hf) -f /3 width=3 by pr_fcla_push, ex2_intro/
+| #f #n #_ #IH #f1 #f2 #H
+ elim (pr_sor_inv_next ⌠H) -H [1,3,4: * |*: // ] #g1 #g2 #Hf #H1 #H2 destruct
+ elim (IH ⌠Hf) -f /3 width=3 by pr_fcla_push, pr_fcla_next, nle_succ_bi, nle_succ_dx, ex2_intro/
+]
+qed-.
+
+(*** sor_fwd_fcla_dx_ex *)
+lemma pr_sor_des_fcla_dx:
+ âf,n. đâŞf⍠â n â âf1,f2. f1 â f2 â f â
+ âân2. đâŞf2⍠â n2 & n2 ⤠n.
+/3 width=4 by pr_sor_des_fcla_sn, pr_sor_comm/ qed-.