/2 width=1 by rtc_ist_plus/ qed.
lemma rtc_ist_succ (n) (c): ðâŠn,câŦ â ðâŠân,c+ððâŦ.
-#n #c #H >nplus_one_dx
+#n #c #H >nplus_unit_dx
/2 width=1 by rtc_ist_plus/
qed.
elim (rtc_ist_inv_plus âĶ H) -H #n1 #n2 #Hn1 #Hn2 #H destruct //
qed-.
-lemma rtc_ist_inv_plus_one_dx:
+lemma rtc_ist_inv_plus_unit_dx:
ân,c1,c2. ðâŠn,c1 + c2âŦ â ðâŠð,c2âŦ â
ââm. ðâŠm,c1âŦ & n = âm.
#n #c1 #c2 #H #H2 destruct