X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matitaB%2Fmatita%2Flibrary%2FQ%2Fratio%2Frinv.ma;fp=matitaB%2Fmatita%2Flibrary%2FQ%2Fratio%2Frinv.ma;h=72c152c2567fea5b745f31ff48948f6fe7489bc0;hb=cacbe3c6493ddce76c4c13379ade271d8dd172e8;hp=0000000000000000000000000000000000000000;hpb=f04a064bb34aabaf91dc0c48e3b08b37ecd7b0a2;p=helm.git

diff --git a/matitaB/matita/library/Q/ratio/rinv.ma b/matitaB/matita/library/Q/ratio/rinv.ma
new file mode 100644
index 000000000..72c152c25
--- /dev/null
+++ b/matitaB/matita/library/Q/ratio/rinv.ma
@@ -0,0 +1,31 @@
+(**************************************************************************)
+(*       ___	                                                            *)
+(*      ||M||                                                             *)
+(*      ||A||       A project by Andrea Asperti                           *)
+(*      ||T||                                                             *)
+(*      ||I||       Developers:                                           *)
+(*      ||T||       A.Asperti, C.Sacerdoti Coen,                          *)
+(*      ||A||       E.Tassi, S.Zacchiroli                                 *)
+(*      \   /                                                             *)
+(*       \ /        This file is distributed under the terms of the       *)
+(*        v         GNU Lesser General Public License Version 2.1         *)
+(*                                                                        *)
+(**************************************************************************)
+
+include "Q/ratio/ratio.ma".
+include "Q/fraction/finv.ma".
+
+definition rinv : ratio \to ratio \def
+\lambda r:ratio.
+  match r with
+  [one \Rightarrow one
+  | (frac f) \Rightarrow frac (finv f)].
+
+theorem rinv_rinv: ∀r. rinv (rinv r) = r.
+ intro;
+ elim r;
+  [ reflexivity
+  | simplify;
+    rewrite > finv_finv;
+    reflexivity]
+qed.