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+(* -*- coding: utf-8 -*- *)
+(************************************************************************)
+(* v * The Coq Proof Assistant / The Coq Development Team *)
+(* <O___,, * CNRS-Ecole Polytechnique-INRIA Futurs-Universite Paris Sud *)
+(* \VV/ **************************************************************)
+(* // * This file is distributed under the terms of the *)
+(* * GNU Lesser General Public License Version 2.1 *)
+(************************************************************************)
+(* *)
+(* Micromega: A reflexive tactic using the Positivstellensatz *)
+(* *)
+(* Frédéric Besson (Irisa/Inria) 2006-2008 *)
+(* *)
+(************************************************************************)
+
+Require Import List.
+Require Setoid.
+
+Set Implicit Arguments.
+
+(* Refl of '->' '/\': basic properties *)
+
+Fixpoint make_impl (A : Type) (eval : A -> Prop) (l : list A) (goal : Prop) {struct l} : Prop :=
+ match l with
+ | nil => goal
+ | cons e l => (eval e) -> (make_impl eval l goal)
+ end.
+
+Theorem make_impl_true :
+ forall (A : Type) (eval : A -> Prop) (l : list A), make_impl eval l True.
+Proof.
+induction l as [| a l IH]; simpl.
+trivial.
+intro; apply IH.
+Qed.
+
+Fixpoint make_conj (A : Type) (eval : A -> Prop) (l : list A) {struct l} : Prop :=
+ match l with
+ | nil => True
+ | cons e nil => (eval e)
+ | cons e l2 => ((eval e) /\ (make_conj eval l2))
+ end.
+
+Theorem make_conj_cons : forall (A : Type) (eval : A -> Prop) (a : A) (l : list A),
+ make_conj eval (a :: l) <-> eval a /\ make_conj eval l.
+Proof.
+intros; destruct l; simpl; tauto.
+Qed.
+
+
+Lemma make_conj_impl : forall (A : Type) (eval : A -> Prop) (l : list A) (g : Prop),
+ (make_conj eval l -> g) <-> make_impl eval l g.
+Proof.
+ induction l.
+ simpl.
+ tauto.
+ simpl.
+ intros.
+ destruct l.
+ simpl.
+ tauto.
+ generalize (IHl g).
+ tauto.
+Qed.
+
+Lemma make_conj_in : forall (A : Type) (eval : A -> Prop) (l : list A),
+ make_conj eval l -> (forall p, In p l -> eval p).
+Proof.
+ induction l.
+ simpl.
+ tauto.
+ simpl.
+ intros.
+ destruct l.
+ simpl in H0.
+ destruct H0.
+ subst; auto.
+ tauto.
+ destruct H.
+ destruct H0.
+ subst;auto.
+ apply IHl; auto.
+Qed.
+
+
+
+Lemma make_conj_app : forall A eval l1 l2, @make_conj A eval (l1 ++ l2) <-> @make_conj A eval l1 /\ @make_conj A eval l2.
+Proof.
+ induction l1.
+ simpl.
+ tauto.
+ intros.
+ change ((a::l1) ++ l2) with (a :: (l1 ++ l2)).
+ rewrite make_conj_cons.
+ rewrite IHl1.
+ rewrite make_conj_cons.
+ tauto.
+Qed.
+
+Lemma not_make_conj_cons : forall (A:Type) (t:A) a eval (no_middle_eval : (eval t) \/ ~ (eval t)),
+ ~ make_conj eval (t ::a) -> ~ (eval t) \/ (~ make_conj eval a).
+Proof.
+ intros.
+ simpl in H.
+ destruct a.
+ tauto.
+ tauto.
+Qed.
+
+Lemma not_make_conj_app : forall (A:Type) (t:list A) a eval
+ (no_middle_eval : forall d, eval d \/ ~ eval d) ,
+ ~ make_conj eval (t ++ a) -> (~ make_conj eval t) \/ (~ make_conj eval a).
+Proof.
+ induction t.
+ simpl.
+ tauto.
+ intros.
+ simpl ((a::t)++a0)in H.
+ destruct (@not_make_conj_cons _ _ _ _ (no_middle_eval a) H).
+ left ; red ; intros.
+ apply H0.
+ rewrite make_conj_cons in H1.
+ tauto.
+ destruct (IHt _ _ no_middle_eval H0).
+ left ; red ; intros.
+ apply H1.
+ rewrite make_conj_cons in H2.
+ tauto.
+ right ; auto.
+Qed.