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(* 02110-1301 USA                                                     *)
(* Contribution to the Coq Library   V6.3 (July 1999)                    *)
(****************************************************************)
(*           The Calculus of Inductive Constructions            *)
(*                       COQ v5.10                              *)
(*                                                              *)
(* Laurent Arditi.  Laboratoire I3S. CNRS ura 1376.             *)
(* Universite de Nice - Sophia Antipolis                        *)
(* arditi@unice.fr, http://wwwi3s.unice.fr/~arditi/lolo.html    *)
(*                                                              *)
(* date: may 1995                                               *)
(* file: Arith_compl.v                                          *)
(* contents: additionnal lemmas on plus,mult,minus,le...        *)
(* definitions of 2^ and factorial, lemmas about them           *)
(****************************************************************)
Require Export Plus.
Require Export Mult.
Require Export Lt.
Require Export Le.
Require Export Gt.
(****************************************************************)
(* Complements sur plus et mult *)
intros; rewrite plus_comm; auto with arith.
Qed. Hint Resolve plus_n_SO.
intros.
rewrite (plus_comm x y).
rewrite (plus_comm x z).
rewrite plus_comm.
symmetry  in |- *.
rewrite plus_comm.
rewrite plus_permute.
auto with arith.
Qed. Hint Resolve plus_permute2.

Lemma mult_sym : forall a b : nat, a * b = b * a.