1 files changed, 489 insertions, 317 deletions

diff --git a/theories/FSets/FSetProperties.v b/theories/FSets/FSetProperties.v
index 6e93a546..7413b06b 100644
--- a/theories/FSets/FSetProperties.v
+++ b/theories/FSets/FSetProperties.v
@@ -6,7 +6,7 @@
 (*         *       GNU Lesser General Public License Version 2.1       *)
 (***********************************************************************)
 
-(* $Id: FSetProperties.v 8853 2006-05-23 18:17:38Z herbelin $ *)
+(* $Id: FSetProperties.v 11064 2008-06-06 17:00:52Z letouzey $ *)
 
 (** * Finite sets library *)
 
@@ -16,414 +16,259 @@
     [In x s] instead of [mem x s=true], 
     [Equal s s'] instead of [equal s s'=true], etc. *)
 
-Require Export FSetInterface. 
-Require Import FSetFacts.
+Require Export FSetInterface.
+Require Import DecidableTypeEx FSetFacts FSetDecide.
 Set Implicit Arguments.
 Unset Strict Implicit.
 
-Hint Unfold transpose compat_op compat_nat.
+Hint Unfold transpose compat_op.
 Hint Extern 1 (Setoid_Theory _ _) => constructor; congruence.
 
-Module Properties (M: S).
-  Module ME:=OrderedTypeFacts(M.E).
-  Import ME. (* for ME.eq_dec *)
-  Import M.E.
-  Import M.
-  Import Logic. (* to unmask [eq] *)  
-  Import Peano. (* to unmask [lt] *)
-  
-   (** Results about lists without duplicates *)
+(** First, a functor for Weak Sets. Since the signature [WS] includes
+    an EqualityType and not a stronger DecidableType, this functor
+    should take two arguments in order to compensate this. *)
 
-  Module FM := Facts M.
-  Import FM.
-
-  Definition Add (x : elt) (s s' : t) :=
-    forall y : elt, In y s' <-> E.eq x y \/ In y s.
+Module WProperties (Import E : DecidableType)(M : WSfun E).
+  Module Import Dec := WDecide E M.
+  Module Import FM := Dec.F (* FSetFacts.WFacts E M *).
+  Import M.
 
   Lemma In_dec : forall x s, {In x s} + {~ In x s}.
   Proof.
   intros; generalize (mem_iff s x); case (mem x s); intuition.
   Qed.
 
-  Section BasicProperties.
-
-  (** properties of [Equal] *)
+  Definition Add x s s' := forall y, In y s' <-> E.eq x y \/ In y s.
 
-  Lemma equal_refl : forall s, s[=]s.
+  Lemma Add_Equal : forall x s s', Add x s s' <-> s' [=] add x s.
   Proof.
-  unfold Equal; intuition.
-  Qed.
-
-  Lemma equal_sym : forall s s', s[=]s' -> s'[=]s.
-  Proof.
-  unfold Equal; intros.
-  rewrite H; intuition.
+  unfold Add.
+  split; intros.
+  red; intros.
+  rewrite H; clear H.
+  fsetdec.
+  fsetdec.
   Qed.
+  
+  Ltac expAdd := repeat rewrite Add_Equal.
 
-  Lemma equal_trans : forall s1 s2 s3, s1[=]s2 -> s2[=]s3 -> s1[=]s3.
-  Proof.
-  unfold Equal; intros.
-  rewrite H; exact (H0 a).
-  Qed.
+  Section BasicProperties.
 
   Variable s s' s'' s1 s2 s3 : t.
   Variable x x' : elt.
 
-  (** properties of [Subset] *)
-  
-  Lemma subset_refl : s[<=]s. 
-  Proof.
-  unfold Subset; intuition.
-  Qed.
+  Lemma equal_refl : s[=]s.
+  Proof. fsetdec. Qed.
 
-  Lemma subset_antisym : s[<=]s' -> s'[<=]s -> s[=]s'.
-  Proof.
-  unfold Subset, Equal; intuition.
-  Qed.
+  Lemma equal_sym : s[=]s' -> s'[=]s.
+  Proof. fsetdec. Qed.
+
+  Lemma equal_trans : s1[=]s2 -> s2[=]s3 -> s1[=]s3.
+  Proof. fsetdec. Qed.
+
+  Lemma subset_refl : s[<=]s. 
+  Proof. fsetdec. Qed.
 
   Lemma subset_trans : s1[<=]s2 -> s2[<=]s3 -> s1[<=]s3.
-  Proof.
-  unfold Subset; intuition.
-  Qed.
+  Proof. fsetdec. Qed.
+
+  Lemma subset_antisym : s[<=]s' -> s'[<=]s -> s[=]s'.
+  Proof. fsetdec. Qed.
 
   Lemma subset_equal : s[=]s' -> s[<=]s'.
-  Proof.
-  unfold Subset, Equal; firstorder.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma subset_empty : empty[<=]s.
-  Proof.
-  unfold Subset; intros a; set_iff; intuition.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma subset_remove_3 : s1[<=]s2 -> remove x s1 [<=] s2.
-  Proof.
-  unfold Subset; intros H a; set_iff; intuition.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma subset_diff : s1[<=]s3 -> diff s1 s2 [<=] s3.
-  Proof.
-  unfold Subset; intros H a; set_iff; intuition.
-  Qed.
-
+  Proof. fsetdec. Qed.
+ 
   Lemma subset_add_3 : In x s2 -> s1[<=]s2 -> add x s1 [<=] s2.
-  Proof.
-  unfold Subset; intros H H0 a; set_iff; intuition.
-  rewrite <- H2; auto.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma subset_add_2 : s1[<=]s2 -> s1[<=] add x s2.
-  Proof.
-  unfold Subset; intuition.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma in_subset : In x s1 -> s1[<=]s2 -> In x s2.
-  Proof.
-  unfold Subset; intuition.
-  Qed.
+  Proof. fsetdec. Qed.
  
   Lemma double_inclusion : s1[=]s2 <-> s1[<=]s2 /\ s2[<=]s1.
-  Proof.
-  unfold Subset, Equal; split; intros; intuition; generalize (H a); intuition.
-  Qed.
-
-  (** properties of [empty] *)
+  Proof. intuition fsetdec. Qed.
 
   Lemma empty_is_empty_1 : Empty s -> s[=]empty.
-  Proof.
-  unfold Empty, Equal; intros; generalize (H a); set_iff; tauto.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma empty_is_empty_2 : s[=]empty -> Empty s.
-  Proof.
-  unfold Empty, Equal; intros; generalize (H a); set_iff; tauto.
-  Qed.
-
-  (** properties of [add] *)
+  Proof. fsetdec. Qed.
 
   Lemma add_equal : In x s -> add x s [=] s.
-  Proof.
-  unfold Equal; intros; set_iff; intuition.
-  rewrite <- H1; auto.
-  Qed.
+  Proof. fsetdec. Qed.
  
   Lemma add_add : add x (add x' s) [=] add x' (add x s).
-  Proof. 
-  unfold Equal; intros; set_iff; tauto.
-  Qed.
-
-  (** properties of [remove] *)
+  Proof. fsetdec. Qed.
 
   Lemma remove_equal : ~ In x s -> remove x s [=] s.
-  Proof.
-  unfold Equal; intros; set_iff; intuition.
-  rewrite H1 in H; auto.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma Equal_remove : s[=]s' -> remove x s [=] remove x s'.
-  Proof.
-  intros; rewrite H; apply equal_refl.
-  Qed.
-
-  (** properties of [add] and [remove] *)
+  Proof. fsetdec. Qed.
 
   Lemma add_remove : In x s -> add x (remove x s) [=] s.
-  Proof.
-  unfold Equal; intros; set_iff; elim (eq_dec x a); intuition.
-  rewrite <- H1; auto.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma remove_add : ~In x s -> remove x (add x s) [=] s.
-  Proof.
-  unfold Equal; intros; set_iff; elim (eq_dec x a); intuition.
-  rewrite H1 in H; auto.
-  Qed.
-
-  (** properties of [singleton] *)
+  Proof. fsetdec. Qed.
 
   Lemma singleton_equal_add : singleton x [=] add x empty.
-  Proof.
-  unfold Equal; intros; set_iff; intuition.
-  Qed.
-
-  (** properties of [union] *)
+  Proof. fsetdec. Qed.
 
   Lemma union_sym : union s s' [=] union s' s.
-  Proof.
-  unfold Equal; intros; set_iff; tauto.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma union_subset_equal : s[<=]s' -> union s s' [=] s'.
-  Proof.
-  unfold Subset, Equal; intros; set_iff; intuition.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma union_equal_1 : s[=]s' -> union s s'' [=] union s' s''.
-  Proof.
-  intros; rewrite H; apply equal_refl.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma union_equal_2 : s'[=]s'' -> union s s' [=] union s s''.
-  Proof.
-  intros; rewrite H; apply equal_refl.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma union_assoc : union (union s s') s'' [=] union s (union s' s'').
-  Proof.
-  unfold Equal; intros; set_iff; tauto.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma add_union_singleton : add x s [=] union (singleton x) s.
-  Proof.
-  unfold Equal; intros; set_iff; tauto.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma union_add : union (add x s) s' [=] add x (union s s').
-  Proof.
-  unfold Equal; intros; set_iff; tauto.
-  Qed.
+  Proof. fsetdec. Qed.
+
+  Lemma union_remove_add_1 : 
+   union (remove x s) (add x s') [=] union (add x s) (remove x s').
+  Proof. fsetdec. Qed.
+
+  Lemma union_remove_add_2 : In x s -> 
+   union (remove x s) (add x s') [=] union s s'.
+  Proof. fsetdec. Qed.
 
   Lemma union_subset_1 : s [<=] union s s'.
-  Proof.
-  unfold Subset; intuition.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma union_subset_2 : s' [<=] union s s'.
-  Proof.
-  unfold Subset; intuition.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma union_subset_3 : s[<=]s'' -> s'[<=]s'' -> union s s' [<=] s''.
-  Proof.
-  unfold Subset; intros H H0 a; set_iff; intuition.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma union_subset_4 : s[<=]s' -> union s s'' [<=] union s' s''.
-  Proof. 
-  unfold Subset; intros H a; set_iff; intuition.
-  Qed.
+  Proof. fsetdec. Qed. 
 
   Lemma union_subset_5 : s[<=]s' -> union s'' s [<=] union s'' s'.
-  Proof. 
-  unfold Subset; intros H a; set_iff; intuition.
-  Qed.
+  Proof. fsetdec. Qed. 
 
   Lemma empty_union_1 : Empty s -> union s s' [=] s'.
-  Proof.
-  unfold Equal, Empty; intros; set_iff; firstorder.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma empty_union_2 : Empty s -> union s' s [=] s'.
-  Proof.
-  unfold Equal, Empty; intros; set_iff; firstorder.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma not_in_union : ~In x s -> ~In x s' -> ~In x (union s s'). 
-  Proof.
-  intros; set_iff; intuition. 
-  Qed.  
-
-  (** properties of [inter] *)
+  Proof. fsetdec. Qed.
 
   Lemma inter_sym : inter s s' [=] inter s' s.
-  Proof.
-  unfold Equal; intros; set_iff; tauto.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma inter_subset_equal : s[<=]s' -> inter s s' [=] s.
-  Proof.
-  unfold Equal; intros; set_iff; intuition.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma inter_equal_1 : s[=]s' -> inter s s'' [=] inter s' s''.
-  Proof.
-  intros; rewrite H; apply equal_refl.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma inter_equal_2 : s'[=]s'' -> inter s s' [=] inter s s''.
-  Proof.
-  intros; rewrite H; apply equal_refl.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma inter_assoc : inter (inter s s') s'' [=] inter s (inter s' s'').
-  Proof.
-  unfold Equal; intros; set_iff; tauto.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma union_inter_1 : inter (union s s') s'' [=] union (inter s s'') (inter s' s'').
-  Proof.
-  unfold Equal; intros; set_iff; tauto.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma union_inter_2 : union (inter s s') s'' [=] inter (union s s'') (union s' s'').
-  Proof.
-  unfold Equal; intros; set_iff; tauto.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma inter_add_1 : In x s' -> inter (add x s) s' [=] add x (inter s s').
-  Proof.
-  unfold Equal; intros; set_iff; intuition.
-  rewrite <- H1; auto.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma inter_add_2 : ~ In x s' -> inter (add x s) s' [=] inter s s'.
-  Proof.
-  unfold Equal; intros; set_iff; intuition.
-  destruct H; rewrite H0; auto.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma empty_inter_1 : Empty s -> Empty (inter s s').
-  Proof.
-  unfold Empty; intros; set_iff; firstorder.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma empty_inter_2 : Empty s' -> Empty (inter s s').
-  Proof.
-  unfold Empty; intros; set_iff; firstorder.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma inter_subset_1 : inter s s' [<=] s.
-  Proof.
-  unfold Subset; intro a; set_iff; tauto.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma inter_subset_2 : inter s s' [<=] s'.
-  Proof.
-  unfold Subset; intro a; set_iff; tauto.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma inter_subset_3 :
    s''[<=]s -> s''[<=]s' -> s''[<=] inter s s'.
-  Proof.
-  unfold Subset; intros H H' a; set_iff; intuition.
-  Qed.
-
-  (** properties of [diff] *)
+  Proof. fsetdec. Qed.
 
   Lemma empty_diff_1 : Empty s -> Empty (diff s s'). 
-  Proof.
-  unfold Empty, Equal; intros; set_iff; firstorder.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma empty_diff_2 : Empty s -> diff s' s [=] s'.
-  Proof.
-  unfold Empty, Equal; intros; set_iff; firstorder.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma diff_subset : diff s s' [<=] s.
-  Proof.
-  unfold Subset; intros a; set_iff; tauto.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma diff_subset_equal : s[<=]s' -> diff s s' [=] empty.
-  Proof.
-  unfold Subset, Equal; intros; set_iff; intuition; absurd (In a empty); auto.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma remove_diff_singleton :
    remove x s [=] diff s (singleton x).
-  Proof.
-  unfold Equal; intros; set_iff; intuition.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma diff_inter_empty : inter (diff s s') (inter s s') [=] empty. 
-  Proof.
-  unfold Equal; intros; set_iff; intuition; absurd (In a empty); auto.
-  Qed.
+  Proof. fsetdec. Qed.
 
   Lemma diff_inter_all : union (diff s s') (inter s s') [=] s.
-  Proof.
-  unfold Equal; intros; set_iff; intuition.
-  elim (In_dec a s'); auto.
-  Qed.
-
-  (** properties of [Add] *)
+  Proof. fsetdec. Qed.
 
   Lemma Add_add : Add x s (add x s).
-  Proof.
-   unfold Add; intros; set_iff; intuition.
-  Qed.
+  Proof. expAdd; fsetdec. Qed.
 
   Lemma Add_remove : In x s -> Add x (remove x s) s. 
-  Proof. 
-    unfold Add; intros; set_iff; intuition.
-    elim (eq_dec x y); auto.
-    rewrite <- H1; auto.
-  Qed.
+  Proof. expAdd; fsetdec. Qed.
 
   Lemma union_Add : Add x s s' -> Add x (union s s'') (union s' s'').
-  Proof. 
-  unfold Add; intros; set_iff; rewrite H; tauto.
-  Qed.
+  Proof. expAdd; fsetdec. Qed. 
 
   Lemma inter_Add :
    In x s'' -> Add x s s' -> Add x (inter s s'') (inter s' s'').
-  Proof. 
-  unfold Add; intros; set_iff; rewrite H0; intuition.
-  rewrite <- H2; auto.
-  Qed.  
+  Proof. expAdd; fsetdec. Qed. 
 
   Lemma union_Equal :
    In x s'' -> Add x s s' -> union s s'' [=] union s' s''.
-  Proof. 
-  unfold Add, Equal; intros; set_iff; rewrite H0; intuition. 
-  rewrite <- H1; auto.
-  Qed.  
+  Proof. expAdd; fsetdec. Qed. 
 
   Lemma inter_Add_2 :
    ~In x s'' -> Add x s s' -> inter s s'' [=] inter s' s''.
-  Proof.
-  unfold Add, Equal; intros; set_iff; rewrite H0; intuition.
-  destruct H; rewrite H1; auto.
-  Qed.
+  Proof. expAdd; fsetdec. Qed.
 
   End BasicProperties.
 
-  Hint Immediate equal_sym: set.
-  Hint Resolve equal_refl equal_trans : set.
-
-  Hint Immediate add_remove remove_add union_sym inter_sym: set.
-  Hint Resolve subset_refl subset_equal subset_antisym 
+  Hint Immediate equal_sym add_remove remove_add union_sym inter_sym: set.
+  Hint Resolve equal_refl equal_trans subset_refl subset_equal subset_antisym 
     subset_trans subset_empty subset_remove_3 subset_diff subset_add_3 
     subset_add_2 in_subset empty_is_empty_1 empty_is_empty_2 add_equal
     remove_equal singleton_equal_add union_subset_equal union_equal_1 
@@ -436,6 +281,31 @@ Module Properties (M: S).
     remove_diff_singleton diff_inter_empty diff_inter_all Add_add Add_remove
     Equal_remove add_add : set.
 
+  (** * Properties of elements *)
+
+  Lemma elements_Empty : forall s, Empty s <-> elements s = nil.
+  Proof.
+  intros.
+  unfold Empty.
+  split; intros.
+  assert (forall a, ~ List.In a (elements s)).
+   red; intros.
+   apply (H a).
+   rewrite elements_iff.
+   rewrite InA_alt; exists a; auto.
+  destruct (elements s); auto.
+  elim (H0 e); simpl; auto.
+  red; intros.
+  rewrite elements_iff in H0.
+  rewrite InA_alt in H0; destruct H0.
+  rewrite H in H0; destruct H0 as (_,H0); inversion H0.
+  Qed.
+
+  Lemma elements_empty : elements empty = nil.
+  Proof.
+  rewrite <-elements_Empty; auto with set.
+  Qed.
+
   (** * Alternative (weaker) specifications for [fold] *)
 
   Section Old_Spec_Now_Properties. 
@@ -447,14 +317,14 @@ Module Properties (M: S).
   *)
 
   Lemma fold_0 : 
-      forall s (A : Set) (i : A) (f : elt -> A -> A),
+      forall s (A : Type) (i : A) (f : elt -> A -> A),
       exists l : list elt,
         NoDup l /\
         (forall x : elt, In x s <-> InA E.eq x l) /\
         fold f s i = fold_right f i l.
   Proof.
   intros; exists (rev (elements s)); split.
-  apply NoDupA_rev; auto.
+  apply NoDupA_rev; auto with set.
   exact E.eq_trans.
   split; intros.
   rewrite elements_iff; do 2 rewrite InA_alt.
@@ -468,7 +338,7 @@ Module Properties (M: S).
       [fold_2]. *)
 
   Lemma fold_1 :
-   forall s (A : Set) (eqA : A -> A -> Prop) 
+   forall s (A : Type) (eqA : A -> A -> Prop) 
      (st : Setoid_Theory A eqA) (i : A) (f : elt -> A -> A),
    Empty s -> eqA (fold f s i) i.
   Proof.
@@ -481,7 +351,7 @@ Module Properties (M: S).
   Qed.
 
   Lemma fold_2 :
-   forall s s' x (A : Set) (eqA : A -> A -> Prop)
+   forall s s' x (A : Type) (eqA : A -> A -> Prop)
      (st : Setoid_Theory A eqA) (i : A) (f : elt -> A -> A),
    compat_op E.eq eqA f ->
    transpose eqA f ->
@@ -492,9 +362,21 @@ Module Properties (M: S).
   rewrite Hl2; rewrite Hl'2; clear Hl2 Hl'2.
   apply fold_right_add with (eqA:=E.eq)(eqB:=eqA); auto.
   eauto.
-  exact eq_dec.
   rewrite <- Hl1; auto.
-  intros; rewrite <- Hl1; rewrite <- Hl'1; auto.
+  intros a; rewrite InA_cons; rewrite <- Hl1; rewrite <- Hl'1; 
+   rewrite (H2 a); intuition.
+  Qed.
+
+  (** In fact, [fold] on empty sets is more than equivalent to 
+      the initial element, it is Leibniz-equal to it. *)
+
+  Lemma fold_1b :
+   forall s (A : Type)(i : A) (f : elt -> A -> A),
+   Empty s -> (fold f s i) = i.
+  Proof.
+  intros.
+  rewrite M.fold_1.
+  rewrite elements_Empty in H; rewrite H; simpl; auto.
   Qed.
 
   (** Similar specifications for [cardinal]. *)
@@ -531,41 +413,46 @@ Module Properties (M: S).
 
   (** * Induction principle over sets *)
 
+  Lemma cardinal_Empty : forall s, Empty s <-> cardinal s = 0.
+  Proof.
+  intros.
+  rewrite elements_Empty, M.cardinal_1.
+  destruct (elements s); intuition; discriminate.
+  Qed.
+
   Lemma cardinal_inv_1 : forall s, cardinal s = 0 -> Empty s. 
-  Proof. 
-    intros s; rewrite M.cardinal_1; intros H a; red.
-    rewrite elements_iff.
-    destruct (elements s); simpl in *; discriminate || inversion 1.
+  Proof.
+  intros; rewrite cardinal_Empty; auto. 
   Qed.
   Hint Resolve cardinal_inv_1.
  
   Lemma cardinal_inv_2 :
    forall s n, cardinal s = S n -> { x : elt | In x s }.
   Proof. 
-    intros; rewrite M.cardinal_1 in H.
-    generalize (elements_2 (s:=s)).
-    destruct (elements s); try discriminate. 
-    exists e; auto.
+  intros; rewrite M.cardinal_1 in H.
+  generalize (elements_2 (s:=s)).
+  destruct (elements s); try discriminate. 
+  exists e; auto.
   Qed.
 
-  Lemma Equal_cardinal_aux :
-   forall n s s', cardinal s = n -> s[=]s' -> cardinal s = cardinal s'.
+  Lemma cardinal_inv_2b :
+   forall s, cardinal s <> 0 -> { x : elt | In x s }.
   Proof.
-     simple induction n; intros.
-     rewrite H; symmetry .
-     apply cardinal_1.
-     rewrite <- H0; auto.
-     destruct (cardinal_inv_2 H0) as (x,H2).
-     revert H0.
-     rewrite (cardinal_2 (s:=remove x s) (s':=s) (x:=x)); auto with set.
-     rewrite (cardinal_2 (s:=remove x s') (s':=s') (x:=x)); auto with set.
-     rewrite H1 in H2; auto with set.
+  intro; generalize (@cardinal_inv_2 s); destruct cardinal; 
+   [intuition|eauto].
   Qed.
 
   Lemma Equal_cardinal : forall s s', s[=]s' -> cardinal s = cardinal s'.
   Proof. 
-    intros; apply Equal_cardinal_aux with (cardinal s); auto.
-  Qed.
+  symmetry.
+  remember (cardinal s) as n; symmetry in Heqn; revert s s' Heqn H.
+  induction n; intros.
+  apply cardinal_1; rewrite <- H; auto.
+  destruct (cardinal_inv_2 Heqn) as (x,H2).
+  revert Heqn.
+  rewrite (cardinal_2 (s:=remove x s) (s':=s) (x:=x)); auto with set.
+  rewrite (cardinal_2 (s:=remove x s') (s':=s') (x:=x)); eauto with set.
+  Qed.    
 
   Add Morphism cardinal : cardinal_m.
   Proof.
@@ -574,40 +461,33 @@ Module Properties (M: S).
 
   Hint Resolve Add_add Add_remove Equal_remove cardinal_inv_1 Equal_cardinal.
 
-  Lemma cardinal_induction :
-   forall P : t -> Type,
-   (forall s, Empty s -> P s) ->
-   (forall s s', P s -> forall x, ~In x s -> Add x s s' -> P s') ->
-   forall n s, cardinal s = n -> P s.
-  Proof.
-  simple induction n; intros; auto.
-  destruct (cardinal_inv_2 H) as (x,H0). 
-  apply X0 with (remove x s) x; auto.
-  apply X1; auto.
-  rewrite (cardinal_2 (x:=x)(s:=remove x s)(s':=s)) in H; auto.
-  Qed.
-
   Lemma set_induction :
    forall P : t -> Type,
    (forall s : t, Empty s -> P s) ->
    (forall s s' : t, P s -> forall x : elt, ~In x s -> Add x s s' -> P s') ->
    forall s : t, P s.
   Proof.
-  intros; apply cardinal_induction with (cardinal s); auto.
-  Qed.  
+  intros; remember (cardinal s) as n; revert s Heqn; induction n; intros; auto.
+  destruct (cardinal_inv_2 (sym_eq Heqn)) as (x,H0). 
+  apply X0 with (remove x s) x; auto with set.
+  apply IHn; auto.
+  assert (S n = S (cardinal (remove x s))).
+    rewrite Heqn; apply cardinal_2 with x; auto with set.
+  inversion H; auto.
+  Qed.
 
   (** Other properties of [fold]. *)
 
   Section Fold. 
-  Variables (A:Set)(eqA:A->A->Prop)(st:Setoid_Theory _ eqA).
+  Variables (A:Type)(eqA:A->A->Prop)(st:Setoid_Theory _ eqA).
   Variables (f:elt->A->A)(Comp:compat_op E.eq eqA f)(Ass:transpose eqA f).
 
   Section Fold_1. 
   Variable i i':A.
 
-  Lemma fold_empty : eqA (fold f empty i) i.
+  Lemma fold_empty : (fold f empty i) = i.
   Proof. 
-  apply fold_1; auto.
+  apply fold_1b; auto with set.
   Qed.
 
   Lemma fold_equal : 
@@ -642,7 +522,7 @@ Module Properties (M: S).
   Proof.
   intros.
   sym_st.
-  apply fold_2 with (eqA:=eqA); auto.
+  apply fold_2 with (eqA:=eqA); auto with set.
   Qed.
 
   Lemma remove_fold_2: forall s x, ~In x s -> 
@@ -742,7 +622,8 @@ Module Properties (M: S).
   apply fold_1; auto with set.
   Qed.
 
-  Lemma fold_union: forall s s', (forall x, ~In x s\/~In x s') ->
+  Lemma fold_union: forall s s', 
+   (forall x, ~(In x s/\In x s')) ->
    eqA (fold f (union s s') i) (fold f s (fold f s' i)).
   Proof.
   intros.
@@ -760,8 +641,8 @@ Module Properties (M: S).
    forall s p, fold (fun _ => S) s p = fold (fun _ => S) s 0 + p.
   Proof.
   assert (st := gen_st nat).
-  assert (fe : compat_op E.eq (@eq _) (fun _ => S)) by (unfold compat_op; auto). 
-  assert (fp : transpose (@eq _) (fun _:elt => S)) by (unfold transpose; auto).
+  assert (fe : compat_op E.eq (@Logic.eq _) (fun _ => S)) by (unfold compat_op; auto). 
+  assert (fp : transpose (@Logic.eq _) (fun _:elt => S)) by (unfold transpose; auto).
   intros s p; pattern s; apply set_induction; clear s; intros.
   rewrite (fold_1 st p (fun _ => S) H).
   rewrite (fold_1 st 0 (fun _ => S) H); trivial.
@@ -774,11 +655,11 @@ Module Properties (M: S).
   simpl; auto.
   Qed.
 
-  (** properties of [cardinal] *)
+  (** more properties of [cardinal] *)
 
   Lemma empty_cardinal : cardinal empty = 0.
   Proof.
-  rewrite cardinal_fold; apply fold_1; auto.
+  rewrite cardinal_fold; apply fold_1; auto with set.
   Qed.
 
   Hint Immediate empty_cardinal cardinal_1 : set.
@@ -798,11 +679,11 @@ Module Properties (M: S).
   Proof.
   intros; do 3 rewrite cardinal_fold.
   rewrite <- fold_plus.
-  apply fold_diff_inter with (eqA:=@eq nat); auto.
+  apply fold_diff_inter with (eqA:=@Logic.eq nat); auto.
   Qed.
 
   Lemma union_cardinal: 
-   forall s s', (forall x, ~In x s\/~In x s') -> 
+   forall s s', (forall x, ~(In x s/\In x s')) -> 
    cardinal (union s s')=cardinal s+cardinal s'.
   Proof.
   intros; do 3 rewrite cardinal_fold.
@@ -841,7 +722,7 @@ Module Properties (M: S).
   intros.
   do 4 rewrite cardinal_fold.
   do 2 rewrite <- fold_plus.
-  apply fold_union_inter with (eqA:=@eq nat); auto.
+  apply fold_union_inter with (eqA:=@Logic.eq nat); auto.
   Qed.
 
   Lemma union_cardinal_inter : 
@@ -872,7 +753,7 @@ Module Properties (M: S).
   intros.
   do 2 rewrite cardinal_fold.
   change S with ((fun _ => S) x);
-   apply fold_add with (eqA:=@eq nat); auto.
+   apply fold_add with (eqA:=@Logic.eq nat); auto.
   Qed.
 
   Lemma remove_cardinal_1 :
@@ -881,7 +762,7 @@ Module Properties (M: S).
   intros.
   do 2 rewrite cardinal_fold.
   change S with ((fun _ =>S) x).
-  apply remove_fold_1 with (eqA:=@eq nat); auto.
+  apply remove_fold_1 with (eqA:=@Logic.eq nat); auto.
   Qed.
 
   Lemma remove_cardinal_2 : 
@@ -892,4 +773,295 @@ Module Properties (M: S).
 
   Hint Resolve subset_cardinal union_cardinal add_cardinal_1 add_cardinal_2.
 
+End WProperties.
+
+
+(** A clone of [WProperties] working on full sets. *)
+
+Module Properties (M:S).
+  Module D := OT_as_DT M.E.
+  Include WProperties D M.
 End Properties.
+
+
+(** Now comes some properties specific to the element ordering, 
+    invalid for Weak Sets. *)
+
+Module OrdProperties (M:S).
+  Module ME:=OrderedTypeFacts(M.E).
+  Module Import P := Properties M.
+  Import FM.
+  Import M.E.
+  Import M.
+
+  (** First, a specialized version of SortA_equivlistA_eqlistA: *)
+  Lemma sort_equivlistA_eqlistA : forall l l' : list elt,
+   sort E.lt l -> sort E.lt l' -> equivlistA E.eq l l' -> eqlistA E.eq l l'.
+  Proof.
+  apply SortA_equivlistA_eqlistA; eauto.
+  Qed.
+
+  Definition gtb x y := match E.compare x y with GT _ => true | _ => false end.
+  Definition leb x := fun y => negb (gtb x y).
+
+  Definition elements_lt x s := List.filter (gtb x) (elements s).
+  Definition elements_ge x s := List.filter (leb x) (elements s).
+
+  Lemma gtb_1 : forall x y, gtb x y = true <-> E.lt y x.
+  Proof.
+   intros; unfold gtb; destruct (E.compare x y); intuition; try discriminate; ME.order.
+  Qed.
+
+  Lemma leb_1 : forall x y, leb x y = true <-> ~E.lt y x.
+  Proof.
+   intros; unfold leb, gtb; destruct (E.compare x y); intuition; try discriminate; ME.order.
+  Qed.
+
+  Lemma gtb_compat : forall x, compat_bool E.eq (gtb x).
+  Proof.
+   red; intros x a b H.
+   generalize (gtb_1 x a)(gtb_1 x b); destruct (gtb x a); destruct (gtb x b); auto.
+   intros.
+   symmetry; rewrite H1.
+   apply ME.eq_lt with a; auto.
+   rewrite <- H0; auto.
+   intros.
+   rewrite H0.
+   apply ME.eq_lt with b; auto.
+   rewrite <- H1; auto.
+  Qed.
+
+  Lemma leb_compat : forall x, compat_bool E.eq (leb x).
+  Proof.
+   red; intros x a b H; unfold leb.
+   f_equal; apply gtb_compat; auto.
+  Qed.
+  Hint Resolve gtb_compat leb_compat.
+
+  Lemma elements_split : forall x s, 
+   elements s = elements_lt x s ++ elements_ge x s.
+  Proof.
+  unfold elements_lt, elements_ge, leb; intros.
+  eapply (@filter_split _ E.eq); eauto with set. ME.order. ME.order. ME.order.
+  intros.
+  rewrite gtb_1 in H.
+  assert (~E.lt y x).
+   unfold gtb in *; destruct (E.compare x y); intuition; try discriminate; ME.order.
+  ME.order.
+  Qed.
+
+  Lemma elements_Add : forall s s' x, ~In x s -> Add x s s' -> 
+    eqlistA E.eq (elements s') (elements_lt x s ++ x :: elements_ge x s). 
+  Proof.
+  intros; unfold elements_ge, elements_lt.
+  apply sort_equivlistA_eqlistA; auto with set.
+  apply (@SortA_app _ E.eq); auto.
+  apply (@filter_sort _ E.eq); auto with set; eauto with set.
+  constructor; auto.
+  apply (@filter_sort _ E.eq); auto with set; eauto with set.
+  rewrite ME.Inf_alt by (apply (@filter_sort _ E.eq); eauto with set).
+  intros.
+  rewrite filter_InA in H1; auto; destruct H1.
+  rewrite leb_1 in H2.
+  rewrite <- elements_iff in H1.
+  assert (~E.eq x y).
+   contradict H; rewrite H; auto.
+  ME.order.
+  intros.
+  rewrite filter_InA in H1; auto; destruct H1.
+  rewrite gtb_1 in H3.
+  inversion_clear H2.
+  ME.order.
+  rewrite filter_InA in H4; auto; destruct H4.
+  rewrite leb_1 in H4.
+  ME.order.
+  red; intros a.
+  rewrite InA_app_iff; rewrite InA_cons.
+  do 2 (rewrite filter_InA; auto).
+  do 2 rewrite <- elements_iff.
+  rewrite leb_1; rewrite gtb_1.
+  rewrite (H0 a); intuition.
+  destruct (E.compare a x); intuition.
+  right; right; split; auto.
+  ME.order.
+  Qed.
+
+  Definition Above x s := forall y, In y s -> E.lt y x.
+  Definition Below x s := forall y, In y s -> E.lt x y.
+
+  Lemma elements_Add_Above : forall s s' x, 
+   Above x s -> Add x s s' -> 
+     eqlistA E.eq (elements s') (elements s ++ x::nil).
+  Proof.
+  intros.
+  apply sort_equivlistA_eqlistA; auto with set.
+  apply (@SortA_app _ E.eq); auto with set.
+  intros.
+  inversion_clear H2.
+  rewrite <- elements_iff in H1.
+  apply ME.lt_eq with x; auto.
+  inversion H3.
+  red; intros a.
+  rewrite InA_app_iff; rewrite InA_cons; rewrite InA_nil.
+  do 2 rewrite <- elements_iff; rewrite (H0 a); intuition.
+  Qed.
+
+  Lemma elements_Add_Below : forall s s' x, 
+   Below x s -> Add x s s' -> 
+     eqlistA E.eq (elements s') (x::elements s).
+  Proof.
+  intros.
+  apply sort_equivlistA_eqlistA; auto with set.
+  change (sort E.lt ((x::nil) ++ elements s)).
+  apply (@SortA_app _ E.eq); auto with set.
+  intros.
+  inversion_clear H1.
+  rewrite <- elements_iff in H2.
+  apply ME.eq_lt with x; auto.
+  inversion H3.
+  red; intros a.
+  rewrite InA_cons.
+  do 2 rewrite <- elements_iff; rewrite (H0 a); intuition.
+  Qed.
+
+  (** Two other induction principles on sets: we can be more restrictive 
+      on the element we add at each step.  *)
+
+  Lemma set_induction_max :
+   forall P : t -> Type,
+   (forall s : t, Empty s -> P s) ->
+   (forall s s', P s -> forall x, Above x s -> Add x s s' -> P s') ->
+   forall s : t, P s.
+  Proof.
+  intros; remember (cardinal s) as n; revert s Heqn; induction n; intros; auto.
+  case_eq (max_elt s); intros.
+  apply X0 with (remove e s) e; auto with set.
+  apply IHn.
+  assert (S n = S (cardinal (remove e s))).
+   rewrite Heqn; apply cardinal_2 with e; auto with set.
+  inversion H0; auto.
+  red; intros.
+  rewrite remove_iff in H0; destruct H0.
+  generalize (@max_elt_2 s e y H H0); ME.order.
+
+  assert (H0:=max_elt_3 H).
+  rewrite cardinal_Empty in H0; rewrite H0 in Heqn; inversion Heqn.
+  Qed.
+
+  Lemma set_induction_min :
+   forall P : t -> Type,
+   (forall s : t, Empty s -> P s) ->
+   (forall s s', P s -> forall x, Below x s -> Add x s s' -> P s') ->
+   forall s : t, P s.
+  Proof.
+  intros; remember (cardinal s) as n; revert s Heqn; induction n; intros; auto.
+  case_eq (min_elt s); intros.
+  apply X0 with (remove e s) e; auto with set.
+  apply IHn.
+  assert (S n = S (cardinal (remove e s))).
+   rewrite Heqn; apply cardinal_2 with e; auto with set.
+  inversion H0; auto.
+  red; intros.
+  rewrite remove_iff in H0; destruct H0.
+  generalize (@min_elt_2 s e y H H0); ME.order.
+
+  assert (H0:=min_elt_3 H).
+  rewrite cardinal_Empty in H0; auto; rewrite H0 in Heqn; inversion Heqn.
+  Qed.
+
+  (** More properties of [fold] : behavior with respect to Above/Below *)
+
+  Lemma fold_3 :
+   forall s s' x (A : Type) (eqA : A -> A -> Prop)
+     (st : Setoid_Theory A eqA) (i : A) (f : elt -> A -> A),
+   compat_op E.eq eqA f ->
+   Above x s -> Add x s s' -> eqA (fold f s' i) (f x (fold f s i)).
+  Proof.
+  intros.
+  do 2 rewrite M.fold_1.
+  do 2 rewrite <- fold_left_rev_right.
+  change (f x (fold_right f i (rev (elements s)))) with
+    (fold_right f i (rev (x::nil)++rev (elements s))).
+  apply (@fold_right_eqlistA E.t E.eq A eqA st); auto.
+  rewrite <- distr_rev.
+  apply eqlistA_rev.
+  apply elements_Add_Above; auto.
+  Qed.
+
+  Lemma fold_4 :
+   forall s s' x (A : Type) (eqA : A -> A -> Prop)
+     (st : Setoid_Theory A eqA) (i : A) (f : elt -> A -> A),
+   compat_op E.eq eqA f ->
+   Below x s -> Add x s s' -> eqA (fold f s' i) (fold f s (f x i)).
+  Proof.
+  intros.
+  do 2 rewrite M.fold_1.
+  set (g:=fun (a : A) (e : elt) => f e a).
+  change (eqA (fold_left g (elements s') i) (fold_left g (x::elements s) i)).
+  unfold g.
+  do 2 rewrite <- fold_left_rev_right.
+  apply (@fold_right_eqlistA E.t E.eq A eqA st); auto.
+  apply eqlistA_rev.
+  apply elements_Add_Below; auto.
+  Qed.
+
+  (** The following results have already been proved earlier, 
+    but we can now prove them with one hypothesis less:
+    no need for [(transpose eqA f)]. *)
+
+  Section FoldOpt. 
+  Variables (A:Type)(eqA:A->A->Prop)(st:Setoid_Theory _ eqA).
+  Variables (f:elt->A->A)(Comp:compat_op E.eq eqA f).
+
+  Lemma fold_equal : 
+   forall i s s', s[=]s' -> eqA (fold f s i) (fold f s' i).
+  Proof.
+  intros; do 2 rewrite M.fold_1.
+  do 2 rewrite <- fold_left_rev_right.
+  apply (@fold_right_eqlistA E.t E.eq A eqA st); auto.
+  apply eqlistA_rev.
+  apply sort_equivlistA_eqlistA; auto with set.
+  red; intro a; do 2 rewrite <- elements_iff; auto.
+  Qed.
+
+  Lemma fold_init : forall i i' s, eqA i i' -> 
+   eqA (fold f s i) (fold f s i').
+  Proof. 
+  intros; do 2 rewrite M.fold_1.
+  do 2 rewrite <- fold_left_rev_right.
+  induction (rev (elements s)); simpl; auto.
+  Qed.
+
+  Lemma add_fold : forall i s x, In x s -> 
+   eqA (fold f (add x s) i) (fold f s i).
+  Proof.
+  intros; apply fold_equal; auto with set.
+  Qed.
+
+  Lemma remove_fold_2: forall i s x, ~In x s -> 
+   eqA (fold f (remove x s) i) (fold f s i).
+  Proof.
+  intros.
+  apply fold_equal; auto with set.
+  Qed.
+
+  End FoldOpt.
+
+  (** An alternative version of [choose_3] *)
+
+  Lemma choose_equal : forall s s', Equal s s' -> 
+    match choose s, choose s' with  
+      | Some x, Some x' => E.eq x x'
+      | None, None => True
+      | _, _ => False
+     end.
+  Proof.
+  intros s s' H; 
+  generalize (@choose_1 s)(@choose_2 s)
+             (@choose_1 s')(@choose_2 s')(@choose_3 s s'); 
+  destruct (choose s); destruct (choose s'); simpl; intuition.
+  apply H5 with e; rewrite <-H; auto.
+  apply H5 with e; rewrite H; auto.
+  Qed.
+
+End OrdProperties.