--- /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_2/xoa/ex_3_2.ma".
+include "ground_2/steps/rtc_plus.ma".
+include "ground_2/steps/rtc_isrt.ma".
+
+(* RT-TRANSITION COUNTER ****************************************************)
+
+(* Properties with test for constrained rt-transition counter ***************)
+
+lemma isrt_plus: ân1,n2,c1,c2. ððâŠn1,c1âŦ â ððâŠn2,c2âŦ â ððâŠn1+n2,c1+c2âŦ.
+#n1 #n2 #c1 #c2 * #ri1 #rs1 #H1 * #ri2 #rs2 #H2 destruct
+/2 width=3 by ex1_2_intro/
+qed.
+
+lemma isrt_plus_O1: ân,c1,c2. ððâŠ0,c1âŦ â ððâŠn,c2âŦ â ððâŠn,c1+c2âŦ.
+/2 width=1 by isrt_plus/ qed.
+
+lemma isrt_plus_O2: ân,c1,c2. ððâŠn,c1âŦ â ððâŠ0,c2âŦ â ððâŠn,c1+c2âŦ.
+#n #c1 #c2 #H1 #H2 >(plus_n_O n) /2 width=1 by isrt_plus/
+qed.
+
+lemma isrt_succ: ân,c. ððâŠn,câŦ â ððâŠân,c+ððâŦ.
+/2 width=1 by isrt_plus/ qed.
+
+(* Inversion properties with test for constrained rt-transition counter *****)
+
+lemma isrt_inv_plus: ân,c1,c2. ððâŠn,c1 + c2âŦ â
+ âân1,n2. ððâŠn1,c1âŦ & ððâŠn2,c2âŦ & n1 + n2 = n.
+#n #c1 #c2 * #ri #rs #H
+elim (plus_inv_dx âĶ H) -H #ri1 #rs1 #ti1 #ts1 #ri2 #rs2 #ti2 #ts2 #_ #_ #H1 #H2 #H3 #H4
+elim (plus_inv_O3 âĶ H1) -H1 /3 width=5 by ex3_2_intro, ex1_2_intro/
+qed-.
+
+lemma isrt_inv_plus_O_dx: ân,c1,c2. ððâŠn,c1 + c2âŦ â ððâŠ0,c2âŦ â ððâŠn,c1âŦ.
+#n #c1 #c2 #H #H2
+elim (isrt_inv_plus âĶ H) -H #n1 #n2 #Hn1 #Hn2 #H destruct
+lapply (isrt_inj âĶ Hn2 H2) -c2 #H destruct //
+qed-.
+
+lemma isrt_inv_plus_SO_dx: ân,c1,c2. ððâŠn,c1 + c2âŦ â ððâŠ1,c2âŦ â
+ ââm. ððâŠm,c1âŦ & n = âm.
+#n #c1 #c2 #H #H2
+elim (isrt_inv_plus âĶ H) -H #n1 #n2 #Hn1 #Hn2 #H destruct
+lapply (isrt_inj âĶ Hn2 H2) -c2 #H destruct
+/2 width=3 by ex2_intro/
+qed-.