(************************************************************************)
(*         *   The Coq Proof Assistant / The Coq Development Team       *)
(*  v      *   INRIA, CNRS and contributors - Copyright 1999-2018       *)
(* <O___,, *       (see CREDITS file for the list of authors)           *)
(*   \VV/  **************************************************************)
(*    //   *    This file is distributed under the terms of the         *)
(*         *     GNU Lesser General Public License Version 2.1          *)
(*         *     (see LICENSE file for the text of the license)         *)
(************************************************************************)
(*                                                                      *)
(* Micromega: A reflexive tactic using the Positivstellensatz           *)
(*                                                                      *)
(*  Frédéric Besson (Irisa/Inria) 2006-2011                             *)
(*                                                                      *)
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Require  FSetPositive FSetEqProperties.
(*Declare ML Module "micromega_plugin".*)
Ltac flatten_bool :=
repeat match goal with
[ id : (_ && _)%bool = true |- _ ] =>  destruct (andb_prop _ _ id); clear id
|  [ id : (_ || _)%bool = true |- _ ] =>  destruct (orb_prop _ _ id); clear id
end.
Ltac inv H := inversion H ; try subst ; clear H.
Open Scope Z_scope.
Fixpoint Zeval_expr (env : PolEnv Z) (e: PExpr Z) : Z :=
match e with
| PEc c => c
| PEX x => env x
| PEadd e1 e2 => Zeval_expr env e1 + Zeval_expr env e2
| PEmul e1 e2 => Zeval_expr env e1 * Zeval_expr env e2
| PEpow e1 n  => Z.pow (Zeval_expr env e1) (Z.of_N n)
| PEsub e1 e2 => (Zeval_expr env e1) - (Zeval_expr env e2)
| PEopp e   => Z.opp (Zeval_expr env e)
end.
Definition eval_expr := eval_pexpr  Z.add Z.mul Z.sub Z.opp (fun x => x) (fun x => x) (pow_N 1 Z.mul).
Fixpoint Zeval_const  (e: PExpr Z) : option Z :=
match e with
| PEc c => Some c
| PEX x => None
| PEadd e1 e2 => map_option2 (fun x y => Some (x + y))
(Zeval_const e1) (Zeval_const e2)
| PEmul e1 e2 => map_option2 (fun x y => Some (x * y))
(Zeval_const e1) (Zeval_const e2)
| PEpow e1 n  => map_option (fun x => Some (Z.pow x (Z.of_N n)))
(Zeval_const e1)
| PEsub e1 e2 => map_option2 (fun x y => Some (x - y))
(Zeval_const e1)  (Zeval_const e2)
| PEopp e   => map_option (fun x => Some (Z.opp x)) (Zeval_const e)
end.
Definition Zeval_op2 (o : Op2) : Z -> Z -> Prop :=
match o with
| OpEq =>  @eq Z
| OpNEq => fun x y  => ~ x = y
| OpLe => Z.le
| OpGe => Z.ge
| OpLt => Z.lt
| OpGt => Z.gt
end.
Definition Zeval_formula (env : PolEnv Z) (f : Formula Z):=
let (lhs, op, rhs) := f in
(Zeval_op2 op) (Zeval_expr env lhs) (Zeval_expr env rhs).
Definition Zeval_formula' :=
eval_formula  Z.add Z.mul Z.sub Z.opp (@eq Z) Z.le Z.lt (fun x => x) (fun x => x) (pow_N 1 Z.mul).

Lemma Zeval_formula_compat : forall env f, Zeval_formula env f <-> Zeval_formula' env f.