(***********************************************************************)
(*  v      *   The Coq Proof Assistant  /  The Coq Development Team    *)
(* <O___,, *        INRIA-Rocquencourt  &  LRI-CNRS-Orsay              *)
(*   \VV/  *************************************************************)
(*    //   *      This file is distributed under the terms of the      *)
(*         *       GNU Lesser General Public License Version 2.1       *)
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(*i $Id$ i*)

(** 
  Axiomatisation of a numerical set 

  It will be instantiated by Z and R later on
  We choose to introduce many operation to allow flexibility in definition 
  ([S] is primitive in the definition of [nat] while [add] and [one] 
   are primitive in the definition 
*)

Parameter N:Type.
Parameter zero:N.
Parameter one:N.
Parameter add:N->N->N.
Parameter S:N->N.

(** Relations, equality is defined separately *)
Parameter lt,le,gt,ge:N->N->Prop.