A negligible change in the structure

FiniteSets/disjunction.v

@@ -1,163 +0,0 @@
-(* Logical disjunction in HoTT (see ch. 3 of the book) *)
-Require Import HoTT.
-Require Import lattice notation.
-
-Instance lor : maximum hProp := fun X Y => BuildhProp (Trunc (-1) (sum X Y)).
-
-Delimit Scope logic_scope with L.
-Notation "A ∨ B" := (lor A B) (at level 20, right associativity) : logic_scope.
-Arguments lor _%L _%L.
-Open Scope logic_scope.
-
-Section lor_props.
-  Context `{Univalence}.
-  Variable X Y Z : hProp.
-
-  Local Ltac lor_intros :=
-    let x := fresh in intro x
-             ; repeat (strip_truncations ; destruct x as [x | x]).
-  
-  
-  Lemma lor_assoc : (X ∨ Y) ∨ Z = X ∨ Y ∨ Z.
-  Proof.
-    apply path_iff_hprop ; lor_intros
-    ; apply tr ; auto
-    ; try (left ; apply tr)
-    ; try (right ; apply tr) ; auto.
-  Defined.  
-
-  Lemma lor_comm : X ∨ Y = Y ∨ X.
-  Proof.
-    apply path_iff_hprop ; lor_intros
-    ; apply tr ; auto.
-  Defined.
-
-  Lemma lor_nl : False_hp ∨ X = X.
-  Proof.
-    apply path_iff_hprop ; lor_intros ; try contradiction
-    ; try (refine (tr(inr _))) ; auto.
-  Defined.
-
-  Lemma lor_nr : X ∨ False_hp = X.
-  Proof.
-    apply path_iff_hprop ; lor_intros ; try contradiction
-    ; try (refine (tr(inl _))) ; auto.
-  Defined.
-
-  Lemma lor_idem : X ∨ X = X.
-  Proof.
-    apply path_iff_hprop ; lor_intros
-    ; try(refine (tr(inl _))) ; auto.
-  Defined.
-
-End lor_props.
-
-Instance land : minimum hProp := fun X Y => BuildhProp (prod X Y).
-Instance lfalse : bottom hProp := False_hp.
-
-Notation "A ∧ B" := (land A B) (at level 20, right associativity) : logic_scope.
-Arguments land _%L _%L.
-Open Scope logic_scope.
-
-Section hPropLattice.
-  Context `{Univalence}.
-
-  Instance lor_commutative : Commutative lor.
-  Proof.
-    unfold Commutative.
-    intros.
-    apply lor_comm.
-  Defined.
-
-  Instance land_commutative : Commutative land.
-  Proof.
-    unfold Commutative, land.
-    intros.
-    apply path_hprop.
-    apply equiv_prod_symm.
-  Defined.
-
-  Instance lor_associative : Associative lor.
-  Proof.
-    unfold Associative.
-    intros.
-    apply lor_assoc.
-  Defined.
-
-  Instance land_associative : Associative land.
-  Proof.
-    unfold Associative, land.
-    intros.
-    symmetry.
-    apply path_hprop.
-    apply equiv_prod_assoc.
-  Defined.
-
-  Instance lor_idempotent : Idempotent lor.
-  Proof.
-    unfold Idempotent.
-    intros.
-    apply lor_idem.
-  Defined.
-
-  Instance land_idempotent : Idempotent land.
-  Proof.
-    unfold Idempotent, land.
-    intros.
-    apply path_iff_hprop ; cbn.
-    - intros [a b] ; apply a.
-    - intros a ; apply (pair a a).
-  Defined.
-
-  Instance lor_neutrall : NeutralL lor lfalse.
-  Proof.
-    unfold NeutralL.
-    intros.
-    apply lor_nl.
-  Defined.
-
-  Instance lor_neutralr : NeutralR lor lfalse.
-  Proof.
-    unfold NeutralR.
-    intros.
-    apply lor_nr.
-  Defined.
-
-  Instance absorption_orb_andb : Absorption lor land.
-  Proof.
-    unfold Absorption.
-    intros.
-    apply path_iff_hprop ; cbn.
-    - intros X ; strip_truncations.
-      destruct X as [Xx | [Xy1 Xy2]] ; assumption.
-    - intros X.
-      apply (tr (inl X)).
-  Defined.
-
-  Instance absorption_andb_orb : Absorption land lor.
-  Proof.
-    unfold Absorption.
-    intros.
-    apply path_iff_hprop ; cbn.
-    - intros [X Y] ; strip_truncations.
-      assumption.
-    - intros X.
-      split.
-      * assumption.
-      * apply (tr (inl X)).
-  Defined.
-
-  Global Instance lattice_hprop : Lattice hProp :=
-    { commutative_min := _ ;
-      commutative_max := _ ;
-      associative_min := _ ;
-      associative_max := _ ;
-      idempotent_min := _ ;
-      idempotent_max := _ ;
-      neutralL_max := _ ;
-      neutralR_max := _ ;
-      absorption_min_max := _ ;
-      absorption_max_min := _
-  }.
-
-End hPropLattice.

FiniteSets/implementations/lists.v

@@ -1,6 +1,6 @@
 (* Implementation of [FSet A] using lists *)
 Require Import HoTT HitTactics.
-Require Import FSets implementations.interface.
+Require Import FSets set_interface.
 
 Section Operations.
   Context `{Univalence}.

FiniteSets/interfaces/lattice_examples.v

@@ -0,0 +1,250 @@
+(** Some examples of lattices. *)
+Require Import HoTT lattice_interface.
+
+(** [Bool] is a lattice. *)
+Section BoolLattice.
+  Ltac solve_bool :=
+    let x := fresh in
+    repeat (intro x ; destruct x)
+    ; compute
+    ; auto
+    ; try contradiction.
+
+  Instance maximum_bool : maximum Bool := orb.
+  Instance minimum_bool : minimum Bool := andb.
+  Instance bottom_bool : bottom Bool := false.
+
+  Global Instance lattice_bool : Lattice Bool.
+  Proof.
+    split ; solve_bool.
+  Defined.
+
+  Definition and_true : forall b, andb b true = b.
+  Proof.
+    solve_bool.
+  Defined.
+
+  Definition and_false : forall b, andb b false = false.
+  Proof.
+    solve_bool.
+  Defined.
+
+  Definition dist₁ : forall b₁ b₂ b₃,
+      andb b₁ (orb b₂ b₃) = orb (andb b₁ b₂) (andb b₁ b₃).
+  Proof.
+    solve_bool.
+  Defined.
+
+  Definition dist₂ : forall b₁ b₂ b₃,
+      orb b₁ (andb b₂ b₃) = andb (orb b₁ b₂) (orb b₁ b₃).
+  Proof.
+    solve_bool.
+  Defined.
+
+  Definition max_min : forall b₁ b₂,
+      orb (andb b₁ b₂) b₁ = b₁.
+  Proof.
+    solve_bool.
+  Defined.
+End BoolLattice.
+
+Create HintDb bool_lattice_hints.
+Hint Resolve associativity : bool_lattice_hints.
+Hint Resolve (associativity _ _ _)^ : bool_lattice_hints.
+Hint Resolve commutative : bool_lattice_hints.
+Hint Resolve absorb : bool_lattice_hints.
+Hint Resolve idempotency : bool_lattice_hints.
+Hint Resolve neutralityL : bool_lattice_hints.
+Hint Resolve neutralityR : bool_lattice_hints.
+
+Hint Resolve
+     associativity
+     and_true and_false
+     dist₁ dist₂ max_min
+  : bool_lattice_hints.
+
+(** If [B] is a lattice, then [A -> B] is a lattice. *)
+Section fun_lattice.
+  Context {A B : Type}.
+  Context `{Lattice B}.
+  Context `{Funext}.
+
+  Global Instance max_fun : maximum (A -> B) :=
+    fun (f g : A -> B) (a : A) => max_L0 (f a) (g a).
+
+  Global Instance min_fun : minimum (A -> B) :=
+    fun (f g : A -> B) (a : A) => min_L0 (f a) (g a).
+
+  Global Instance bot_fun : bottom (A -> B)
+    := fun _ => empty_L.
+
+  Ltac solve_fun :=
+    compute ; intros ; apply path_forall ; intro ;
+    eauto with lattice_hints typeclass_instances.
+
+  Global Instance lattice_fun : Lattice (A -> B).
+  Proof.
+    split ; solve_fun.
+  Defined.
+End fun_lattice.
+
+(** If [A] is a lattice and [P] is closed under the lattice operations, then [Σ(x:A), P x] is a lattice. *)
+Section sub_lattice.
+  Context {A : Type} {P : A -> hProp}.
+  Context `{Lattice A}.
+  Context {Hmax : forall x y, P x -> P y -> P (max_L0 x y)}.
+  Context {Hmin : forall x y, P x -> P y -> P (min_L0 x y)}.
+  Context {Hbot : P empty_L}.
+
+  Definition AP : Type := sig P.
+
+  Instance botAP : bottom AP := (empty_L ; Hbot).
+
+  Instance maxAP : maximum AP :=
+    fun x y =>
+      match x, y with
+      | (a ; pa), (b ; pb) => (max_L0 a b ; Hmax a b pa pb)
+      end.
+
+  Instance minAP : minimum AP :=
+    fun x y =>
+      match x, y with
+      | (a ; pa), (b ; pb) => (min_L0 a b ; Hmin a b pa pb)
+      end.
+
+  Instance hprop_sub : forall c, IsHProp (P c).
+  Proof.
+    apply _.
+  Defined.
+
+  Ltac solve_sub :=
+    let x := fresh in
+    repeat (intro x ; destruct x)
+    ; simple refine (path_sigma _ _ _ _ _)
+    ; simpl
+    ; try (apply hprop_sub)
+    ; eauto 3 with lattice_hints typeclass_instances.
+
+  Global Instance lattice_sub : Lattice AP.
+  Proof.
+    split ; solve_sub.
+  Defined.
+End sub_lattice.
+
+Instance lor : maximum hProp := fun X Y => BuildhProp (Trunc (-1) (sum X Y)).
+
+Delimit Scope logic_scope with L.
+Notation "A ∨ B" := (lor A B) (at level 20, right associativity) : logic_scope.
+Arguments lor _%L _%L.
+Open Scope logic_scope.
+
+Instance land : minimum hProp := fun X Y => BuildhProp (prod X Y).
+Instance lfalse : bottom hProp := False_hp.
+
+Notation "A ∧ B" := (land A B) (at level 20, right associativity) : logic_scope.
+Arguments land _%L _%L.
+Open Scope logic_scope.
+
+(** [hProp] is a lattice. *)
+Section hPropLattice.
+  Context `{Univalence}.
+
+  Local Ltac lor_intros :=
+    let x := fresh in intro x
+                      ; repeat (strip_truncations ; destruct x as [x | x]).
+
+  Instance lor_commutative : Commutative lor.
+  Proof.
+    intros X Y.
+    apply path_iff_hprop ; lor_intros
+    ; apply tr ; auto.
+  Defined.
+
+  Instance land_commutative : Commutative land.
+  Proof.
+    intros X Y.
+    apply path_hprop.
+    apply equiv_prod_symm.
+  Defined.
+
+  Instance lor_associative : Associative lor.
+  Proof.
+    intros X Y Z.
+    apply path_iff_hprop ; lor_intros
+    ; apply tr ; auto
+    ; try (left ; apply tr)
+    ; try (right ; apply tr) ; auto.
+  Defined.
+
+  Instance land_associative : Associative land.
+  Proof.
+    intros X Y Z.
+    symmetry.
+    apply path_hprop.
+    apply equiv_prod_assoc.
+  Defined.
+
+  Instance lor_idempotent : Idempotent lor.
+  Proof.
+    intros X.
+    apply path_iff_hprop ; lor_intros
+    ; try(refine (tr(inl _))) ; auto.
+  Defined.
+
+  Instance land_idempotent : Idempotent land.
+  Proof.
+    intros X.
+    apply path_iff_hprop ; cbn.
+    - intros [a b] ; apply a.
+    - intros a ; apply (pair a a).
+  Defined.
+
+  Instance lor_neutrall : NeutralL lor lfalse.
+  Proof.
+    intros X.
+    apply path_iff_hprop ; lor_intros ; try contradiction
+    ; try (refine (tr(inr _))) ; auto.
+  Defined.
+
+  Instance lor_neutralr : NeutralR lor lfalse.
+  Proof.
+    intros X.
+    apply path_iff_hprop ; lor_intros ; try contradiction
+    ; try (refine (tr(inl _))) ; auto.
+  Defined.
+
+  Instance absorption_orb_andb : Absorption lor land.
+  Proof.
+    intros Z1 Z2.
+    apply path_iff_hprop ; cbn.
+    - intros X ; strip_truncations.
+      destruct X as [Xx | [Xy1 Xy2]] ; assumption.
+    - intros X.
+      apply (tr (inl X)).
+  Defined.
+
+  Instance absorption_andb_orb : Absorption land lor.
+  Proof.
+    intros Z1 Z2.
+    apply path_iff_hprop ; cbn.
+    - intros [X Y] ; strip_truncations.
+      assumption.
+    - intros X.
+      split.
+      * assumption.
+      * apply (tr (inl X)).
+  Defined.
+
+  Global Instance lattice_hprop : Lattice hProp :=
+    { commutative_min := _ ;
+      commutative_max := _ ;
+      associative_min := _ ;
+      associative_max := _ ;
+      idempotent_min := _ ;
+      idempotent_max := _ ;
+      neutralL_max := _ ;
+      neutralR_max := _ ;
+      absorption_min_max := _ ;
+      absorption_max_min := _
+  }.
+End hPropLattice.

FiniteSets/interfaces/lattice_interface.v

@@ -0,0 +1,115 @@
+(** Interface for lattices and join semilattices. *)
+Require Import HoTT.
+
+Section binary_operation.
+  Definition operation (A : Type) := A -> A -> A.
+  
+  Variable (A : Type)
+           (f : operation A).
+
+  Class Commutative :=
+    commutative : forall x y, f x y = f y x.
+
+  Class Associative :=
+    associativity : forall x y z, f (f x y) z = f x (f y z).
+
+  Class Idempotent :=
+    idempotency : forall x, f x x = x.
+
+  Variable g : operation A.
+
+  Class Absorption :=
+    absorb : forall x y, f x (g x y) = x.
+
+  Variable (n : A).
+
+  Class NeutralL :=
+    neutralityL : forall x, f n x = x.
+
+  Class NeutralR :=
+    neutralityR : forall x, f x n = x.
+End binary_operation.
+
+Arguments Commutative {_} _.
+Arguments Associative {_} _.
+Arguments Idempotent {_} _.
+Arguments NeutralL {_} _ _.
+Arguments NeutralR {_} _ _.
+Arguments Absorption {_} _ _.
+Arguments commutative {_} {_} {_} _ _.
+Arguments associativity {_} {_} {_} _ _ _.
+Arguments idempotency {_} {_} {_} _.
+Arguments neutralityL {_} {_} {_} {_} _.
+Arguments neutralityR {_} {_} {_} {_} _.
+Arguments absorb {_} {_} {_} {_} _ _.
+
+Section lattice_operations.
+  Variable (A : Type).
+
+  Class maximum :=
+    max_L : operation A.
+
+  Class minimum :=
+    min_L : operation A.
+
+  Class bottom :=
+    empty : A.
+End lattice_operations.
+
+Arguments max_L {_} {_} _.
+Arguments min_L {_} {_} _.
+Arguments empty {_}.
+
+Section JoinSemiLattice.
+  Variable A : Type.
+  Context {max_L : maximum A} {empty_L : bottom A}.
+
+  Class JoinSemiLattice :=
+    {
+      commutative_max_js :> Commutative max_L ;
+      associative_max_js :> Associative max_L ;
+      idempotent_max_js :> Idempotent max_L ;
+      neutralL_max_js :> NeutralL max_L empty_L ;
+      neutralR_max_js :> NeutralR max_L empty_L ;
+    }.
+End JoinSemiLattice.
+
+Arguments JoinSemiLattice _ {_} {_}.
+
+Create HintDb joinsemilattice_hints.
+Hint Resolve associativity : joinsemilattice_hints.
+Hint Resolve (associativity _ _ _)^ : joinsemilattice_hints.
+Hint Resolve commutative : joinsemilattice_hints.
+Hint Resolve idempotency : joinsemilattice_hints.
+Hint Resolve neutralityL : joinsemilattice_hints.
+Hint Resolve neutralityR : joinsemilattice_hints.
+
+Section Lattice.
+  Variable A : Type.
+  Context {max_L : maximum A} {min_L : minimum A} {empty_L : bottom A}.
+
+  Class Lattice :=
+    {
+      commutative_min :> Commutative min_L ;
+      commutative_max :> Commutative max_L ;
+      associative_min :> Associative min_L ;
+      associative_max :> Associative max_L ;
+      idempotent_min :> Idempotent min_L ;
+      idempotent_max :> Idempotent max_L ;
+      neutralL_max :> NeutralL max_L empty_L ;
+      neutralR_max :> NeutralR max_L empty_L ;
+      absorption_min_max :> Absorption min_L max_L ;
+      absorption_max_min :> Absorption max_L min_L
+    }.
+End Lattice.
+
+Arguments Lattice _ {_} {_} {_}.
+
+Create HintDb lattice_hints.
+Hint Resolve associativity : lattice_hints.
+Hint Resolve (associativity _ _ _)^ : lattice_hints.
+Hint Resolve commutative : lattice_hints.
+Hint Resolve absorb : lattice_hints.
+Hint Resolve idempotency : lattice_hints.
+Hint Resolve neutralityL : lattice_hints.
+Hint Resolve neutralityR : lattice_hints.

FiniteSets/interfaces/monad_interface.v

@@ -0,0 +1,45 @@
+(** The structure of a monad. *)
+Require Import HoTT.
+
+Section functor.
+  Variable (F : Type -> Type).
+  Context `{Functorish F}.
+
+  Class Functor :=
+    {
+      fmap_compose {A B C : Type} (f : A -> B) (g : B -> C) :
+        fmap F (g o f) = fmap F g o fmap F f
+    }.
+End functor.
+  
+Section monad_operations.
+  Variable (F : Type -> Type).
+
+  Class hasPure :=
+    {
+      pure : forall (A : Type), A -> F A
+    }.
+
+  Class hasBind :=
+    {
+      bind : forall (A : Type), F(F A) -> F A
+    }.
+End monad_operations.
+
+Arguments pure {_} {_} _ _.
+Arguments bind {_} {_} _ _.
+
+Section monad.
+  Variable (F : Type -> Type).
+  Context `{Functor F} `{hasPure F} `{hasBind F}.
+
+  Class Monad :=
+    {
+      bind_assoc : forall {A : Type},
+        bind A o bind (F A) = bind A o fmap F (bind A) ;
+      bind_neutral_l : forall {A : Type},
+          bind A o pure (F A) = idmap ;
+      bind_neutral_r : forall {A : Type},
+          bind A o fmap F (pure A) = idmap
+    }.
+End monad.

FiniteSets/interfaces/set_interface.v

@@ -0,0 +1,331 @@
+Require Import HoTT.
+Require Import FSets lattice_interface.
+
+Section interface.
+  Context `{Univalence}.
+  Variable (T : Type -> Type)
+           (f : forall A, T A -> FSet A).
+  Context `{forall A, hasMembership (T A) A
+          , forall A, hasEmpty (T A)
+          , forall A, hasSingleton (T A) A
+          , forall A, hasUnion (T A)
+          , forall A, hasComprehension (T A) A}.
+
+  Class sets :=
+    {
+      f_empty : forall A, f A ∅ = ∅ ;
+      f_singleton : forall A a, f A (singleton a) = {|a|};
+      f_union : forall A X Y, f A (union X Y) = (f A X) ∪ (f A Y);
+      f_filter : forall A φ X, f A (filter φ X) = {| f A X & φ |};
+      f_member : forall A a X, member a X = a ∈ (f A X)
+    }.
+
+  Global Instance f_surjective A `{sets} : IsSurjection (f A).
+  Proof.
+    unfold IsSurjection.
+    hinduction ; try (intros ; apply path_ishprop).
+    - simple refine (BuildContr _ _ _).
+      * refine (tr(∅;_)).
+        apply f_empty.
+      * intros ; apply path_ishprop.
+    - intro a.
+      simple refine (BuildContr _ _ _).
+      * refine (tr({|a|};_)).
+        apply f_singleton.
+      * intros ; apply path_ishprop.
+    - intros Y1 Y2 [X1' ?] [X2' ?].
+      simple refine (BuildContr _ _ _).
+      * simple refine (Trunc_rec _ X1') ; intros [X1 fX1].
+        simple refine (Trunc_rec _ X2') ; intros [X2 fX2].
+        refine (tr(X1 ∪ X2;_)).
+        rewrite f_union, fX1, fX2.
+        reflexivity.
+      * intros ; apply path_ishprop.
+  Defined.
+
+End interface.
+
+Section quotient_surjection.
+  Variable (A B : Type)
+           (f : A -> B)
+           (H : IsSurjection f).
+  Context `{IsHSet B} `{Univalence}.
+
+  Definition f_eq : relation A := fun a1 a2 => f a1 = f a2.
+  Definition quotientB : Type := quotient f_eq.
+
+  Global Instance quotientB_recursion : HitRecursion quotientB :=
+    {
+      indTy := _;
+      recTy :=
+        forall (P : Type) (HP: IsHSet P) (u : A -> P),
+          (forall x y : A, f_eq x y -> u x = u y) -> quotientB -> P;
+      H_inductor := quotient_ind f_eq ;
+      H_recursor := @quotient_rec _ f_eq _
+    }.
+
+  Global Instance R_refl : Reflexive f_eq.
+  Proof.
+    intro.
+    reflexivity.
+  Defined.
+
+  Global Instance R_sym : Symmetric f_eq.
+  Proof.
+    intros a b Hab.
+    apply (Hab^).
+  Defined.
+
+  Global Instance R_trans : Transitive f_eq.
+  Proof.
+    intros a b c Hab Hbc.
+    apply (Hab @ Hbc).
+  Defined.
+
+  Definition quotientB_to_B : quotientB -> B.
+  Proof.
+    hrecursion.
+    - apply f.
+    - done.
+  Defined.
+    
+  Instance quotientB_emb : IsEmbedding (quotientB_to_B).
+  Proof.
+    apply isembedding_isinj_hset.
+    unfold isinj.
+    hrecursion ; [ | intros; apply path_ishprop ].
+    intro.
+    hrecursion ; [ | intros; apply path_ishprop ].
+    intros.
+      by apply related_classes_eq.
+  Defined.
+
+  Instance quotientB_surj : IsSurjection (quotientB_to_B).
+  Proof.
+    apply BuildIsSurjection.
+    intros Y.
+    destruct (H Y).
+    simple refine (Trunc_rec _ center) ; intros [a fa].
+    apply (tr(class_of _ a;fa)).
+  Defined.
+
+  Definition quotient_iso : quotientB <~> B.
+  Proof.
+    refine (BuildEquiv _ _ quotientB_to_B _).
+    apply isequiv_surj_emb ; apply _.
+  Defined.
+
+  Definition reflect_eq : forall (X Y : A),
+      f X = f Y -> f_eq X Y.
+  Proof.
+    done.
+  Defined.
+
+  Lemma same_class : forall (X Y : A),
+      class_of f_eq X = class_of f_eq Y -> f_eq X Y.
+  Proof.
+    intros.
+    simple refine (classes_eq_related _ _ _ _) ; assumption.
+  Defined.
+
+End quotient_surjection.
+
+Arguments quotient_iso {_} {_} _ {_} {_} {_}.
+  
+Ltac reduce T :=
+  intros ;
+  repeat (rewrite (f_empty T _)
+          || rewrite (f_singleton T _)
+          || rewrite (f_union T _)
+          || rewrite (f_filter T _)
+          || rewrite (f_member T _)).
+
+Section quotient_properties.
+  Variable (T : Type -> Type).
+  Variable (f : forall {A : Type}, T A -> FSet A).
+  Context `{sets T f}.
+
+  Definition set_eq A := f_eq (T A) (FSet A) (f A).
+  Definition View A : Type := quotientB (T A) (FSet A) (f A).
+
+  Instance f_is_surjective A : IsSurjection (f A).
+  Proof.
+    apply (f_surjective T f A).
+  Defined.
+    
+  Global Instance view_union (A : Type) : hasUnion (View A).
+  Proof.
+    intros X Y.
+    apply (quotient_iso _)^-1.
+    simple refine (union _ _).
+    - simple refine (quotient_iso (f A) X).
+    - simple refine (quotient_iso (f A) Y).
+  Defined.
+
+  Definition well_defined_union (A : Type) (X Y : T A) :
+    (class_of _ X) ∪ (class_of _ Y) = class_of _ (X ∪ Y).
+  Proof.
+    rewrite <- (eissect (quotient_iso _)).
+    simpl.
+    rewrite (f_union T _).
+    reflexivity.
+  Defined.
+
+  Global Instance view_comprehension (A : Type) : hasComprehension (View A) A.
+  Proof.
+    intros ϕ X.
+    apply (quotient_iso _)^-1.
+    simple refine ({|_ & ϕ|}).
+    apply (quotient_iso (f A) X).
+  Defined.
+
+  Definition well_defined_filter (A : Type) (ϕ : A -> Bool) (X : T A) :
+    {|class_of _ X & ϕ|} = class_of _ {|X & ϕ|}.
+  Proof.
+    rewrite <- (eissect (quotient_iso _)).
+    simpl.
+    rewrite (f_filter T _).
+    reflexivity.
+  Defined.
+
+  Global Instance View_empty A : hasEmpty (View A).
+  Proof.
+    apply ((quotient_iso _)^-1 ∅).
+  Defined.
+
+  Definition well_defined_empty A : ∅ = class_of (set_eq A) ∅.
+  Proof.
+    rewrite <- (eissect (quotient_iso _)).
+    simpl.
+    rewrite (f_empty T _).
+    reflexivity.
+  Defined.  
+
+  Global Instance View_singleton A: hasSingleton (View A) A.
+  Proof.
+    intro a ; apply ((quotient_iso _)^-1 {|a|}).
+  Defined.
+
+  Definition well_defined_sungleton A (a : A) : {|a|} = class_of _ {|a|}.
+  Proof.
+    rewrite <- (eissect (quotient_iso _)).
+    simpl.
+    rewrite (f_singleton T _).
+    reflexivity.
+  Defined.  
+  
+  Global Instance View_member A : hasMembership (View A) A.
+  Proof.
+    intros a ; unfold View.
+    hrecursion.
+    - apply (member a).
+    - intros X Y HXY.
+      reduce T.
+      apply (ap _ HXY).
+  Defined.
+
+  Instance View_max A : maximum (View A).
+  Proof.
+    apply view_union.
+  Defined.
+
+  Hint Unfold Commutative Associative Idempotent NeutralL NeutralR View_max view_union.
+
+  Instance bottom_view A : bottom (View A).
+  Proof.
+    apply View_empty.
+  Defined.
+
+  Ltac sq1 := autounfold ; intros ; try f_ap
+                         ; rewrite ?(eisretr (quotient_iso _))
+                         ; eauto with lattice_hints typeclass_instances.
+
+  Ltac sq2 := autounfold ; intros
+              ; rewrite <- (eissect (quotient_iso _)), ?(eisretr (quotient_iso _))
+              ; f_ap ; simpl
+              ; reduce T ; eauto with lattice_hints typeclass_instances.
+
+  Global Instance view_lattice A : JoinSemiLattice (View A).
+  Proof.
+    split ; try sq1 ; try sq2.
+  Defined.
+
+End quotient_properties.
+
+Arguments set_eq {_} _ {_} _ _.
+
+Section properties.
+  Context `{Univalence}.
+  Variable (T : Type -> Type) (f : forall A, T A -> FSet A).
+  Context `{sets T f}.
+
+  Definition set_subset : forall A, T A -> T A -> hProp :=
+    fun A X Y => (f A X) ⊆ (f A Y).
+
+  Definition empty_isIn : forall (A : Type) (a : A),
+    a ∈ ∅ = False_hp.
+  Proof.
+    by (reduce T).
+  Defined.
+
+  Definition singleton_isIn : forall (A : Type) (a b : A),
+    a ∈ {|b|} = merely (a = b).
+  Proof.
+    by (reduce T).
+  Defined.
+
+  Definition union_isIn : forall (A : Type) (a : A) (X Y : T A),
+    a ∈ (X ∪ Y) = lor (a ∈ X) (a ∈ Y).
+  Proof.
+    by (reduce T).
+  Defined.
+
+  Definition filter_isIn : forall (A : Type) (a : A) (ϕ : A -> Bool) (X : T A),
+    member a (filter ϕ X) = if ϕ a then member a X else False_hp.
+  Proof.
+    reduce T.
+    apply properties.comprehension_isIn.
+  Defined.
+
+  Definition reflect_f_eq : forall (A : Type) (X Y : T A),
+      class_of (set_eq f) X = class_of (set_eq f) Y -> set_eq f X Y.
+  Proof.
+    intros.
+    refine (same_class _ _ _ _ _ _) ; assumption.
+  Defined.
+
+  Ltac via_quotient := intros ; apply reflect_f_eq ; simpl
+                       ; rewrite <- ?(well_defined_union T _), <- ?(well_defined_empty T _)
+                       ; eauto with lattice_hints typeclass_instances.  
+
+  Lemma union_comm : forall A (X Y : T A),
+      set_eq f (X ∪ Y) (Y ∪ X).
+  Proof.
+    via_quotient.
+  Defined.
+
+  Lemma union_assoc : forall A (X Y Z : T A),
+    set_eq f ((X ∪ Y) ∪ Z) (X ∪ (Y ∪ Z)).
+  Proof.
+    via_quotient.
+  Defined.
+
+  Lemma union_idem : forall A (X : T A),
+    set_eq f (X ∪ X) X.
+  Proof.
+    via_quotient.
+  Defined.
+
+  Lemma union_neutralL : forall A (X : T A),
+    set_eq f (∅ ∪ X) X.
+  Proof.
+    via_quotient.
+  Defined.
+
+  Lemma union_neutralR : forall A (X : T A),
+    set_eq f (X ∪ ∅) X.
+  Proof.
+    via_quotient.
+  Defined.
+  
+End properties.

FiniteSets/interfaces/set_names.v

@@ -1,52 +1,6 @@
+(** Classes for set operations, so they can be overloaded. *)
 Require Import HoTT.
 
-Section binary_operation.
-  Variable A : Type.
-  
-  Definition operation := A -> A -> A.
-End binary_operation.
-
-Section Defs.
-  Variable A : Type.
-  Variable f : A -> A -> A.
-
-  Class Commutative :=
-    commutative : forall x y, f x y = f y x.
-
-  Class Associative :=
-    associativity : forall x y z, f (f x y) z = f x (f y z).
-
-  Class Idempotent :=
-    idempotency : forall x, f x x = x.
-
-  Variable g : operation A.
-
-  Class Absorption :=
-    absorb : forall x y, f x (g x y) = x.
-
-  Variable n : A.
-
-  Class NeutralL :=
-    neutralityL : forall x, f n x = x.
-
-  Class NeutralR :=
-    neutralityR : forall x, f x n = x.
-
-End Defs.
-
-Arguments Commutative {_} _.
-Arguments Associative {_} _.
-Arguments Idempotent {_} _.
-Arguments NeutralL {_} _ _.
-Arguments NeutralR {_} _ _.
-Arguments Absorption {_} _ _.
-Arguments commutative {_} {_} {_} _ _.
-Arguments associativity {_} {_} {_} _ _ _.
-Arguments idempotency {_} {_} {_} _.
-Arguments neutralityL {_} {_} {_} {_} _.
-Arguments neutralityR {_} {_} {_} {_} _.
-Arguments absorb {_} {_} {_} {_} _ _.
-
 Section structure.
   Variable (T A : Type).
   

FiniteSets/kuratowski/extensionality.v

@@ -1,6 +1,6 @@
 (** Extensionality of the FSets *)
 Require Import HoTT HitTactics.
-Require Import representations.definition fsets.operations.
+Require Import kuratowski.kuratowski_sets.
 
 Section ext.
   Context {A : Type}.

FiniteSets/kuratowski/kuratowski_sets.v

@@ -0,0 +1,165 @@
+(** Definitions of the Kuratowski-finite sets via a HIT *)
+Require Import HoTT HitTactics.
+Require Export set_names lattice_examples.
+
+Module Export FSet.
+  Section FSet.
+    Private Inductive FSet (A : Type) : Type :=
+    | E : FSet A
+    | L : A -> FSet A
+    | U : FSet A -> FSet A -> FSet A.
+
+    Global Instance fset_empty : forall A, hasEmpty (FSet A) := E.
+    Global Instance fset_singleton : forall A, hasSingleton (FSet A) A := L.
+    Global Instance fset_union : forall A, hasUnion (FSet A) := U.
+
+    Variable A : Type.
+
+    Axiom assoc : forall (x y z : FSet A),
+        x ∪ (y ∪ z) = (x ∪ y) ∪ z.
+
+    Axiom comm : forall (x y : FSet A),
+        x ∪ y = y ∪ x.
+
+    Axiom nl : forall (x : FSet A),
+        ∅ ∪ x = x.
+
+    Axiom nr : forall (x : FSet A),
+        x ∪ ∅ = x.
+
+    Axiom idem : forall (x : A),
+        {|x|} ∪ {|x|} = {|x|}.
+
+    Axiom trunc : IsHSet (FSet A).
+
+  End FSet.
+
+  Arguments assoc {_} _ _ _.
+  Arguments comm {_} _ _.
+  Arguments nl {_} _.
+  Arguments nr {_} _.
+  Arguments idem {_} _.
+
+  Section FSet_induction.
+    Variable (A : Type)
+             (P : FSet A -> Type)
+             (H :  forall X : FSet A, IsHSet (P X))
+             (eP : P ∅)
+             (lP : forall a: A, P {|a|})
+             (uP : forall (x y: FSet A), P x -> P y -> P (x ∪ y))
+             (assocP : forall (x y z : FSet A)
+                               (px: P x) (py: P y) (pz: P z),
+                  assoc x y z #
+                        (uP x (y ∪ z) px (uP y z py pz))
+                  =
+                  (uP (x ∪ y) z (uP x y px py) pz))
+             (commP : forall (x y: FSet A) (px: P x) (py: P y),
+                  comm x y #
+                       uP x y px py = uP y x py px)
+             (nlP : forall (x : FSet A) (px: P x),
+                  nl x # uP ∅ x eP px = px)
+             (nrP : forall (x : FSet A) (px: P x),
+                  nr x # uP x ∅ px eP = px)
+             (idemP : forall (x : A),
+                  idem x # uP {|x|} {|x|} (lP x) (lP x) = lP x).
+
+    (* Induction principle *)
+    Fixpoint FSet_ind
+             (x : FSet A)
+             {struct x}
+      : P x
+      := (match x return _ -> _ -> _ -> _ -> _ -> _ -> P x with
+          | E => fun _ _ _ _ _ _ => eP
+          | L a => fun _ _ _ _ _ _ => lP a
+          | U y z => fun _ _ _ _ _ _ => uP y z (FSet_ind y) (FSet_ind z)
+          end) H assocP commP nlP nrP idemP.
+  End FSet_induction.
+
+  Section FSet_recursion.
+    Variable (A : Type)
+             (P : Type)
+             (H: IsHSet P)
+             (e : P)
+             (l : A -> P)
+             (u : P -> P -> P)
+             (assocP : forall (x y z : P), u x (u y z) = u (u x y) z)
+             (commP : forall (x y : P), u x y = u y x)
+             (nlP : forall (x : P), u e x = x)
+             (nrP : forall (x : P), u x e = x)
+             (idemP : forall (x : A), u (l x) (l x) = l x).
+
+    (* Recursion princople *)
+    Definition FSet_rec : FSet A -> P.
+    Proof.
+      simple refine (FSet_ind A _ _ _ _ _ _ _ _ _ _)
+      ; try (intros ; simple refine ((transport_const _ _) @ _)) ; cbn.
+      - apply e.
+      - apply l.
+      - intros x y ; apply u.
+      - apply assocP.
+      - apply commP.
+      - apply nlP.
+      - apply nrP.
+      - apply idemP.
+    Defined.
+  End FSet_recursion.
+
+  Instance FSet_recursion A : HitRecursion (FSet A) :=
+    {
+      indTy := _; recTy := _;
+      H_inductor := FSet_ind A; H_recursor := FSet_rec A
+    }.
+End FSet.
+
+Lemma union_idem {A : Type} : forall x: FSet A, x ∪ x = x.
+Proof.
+  hinduction ; try (intros ; apply set_path2).
+  - apply nl.
+  - apply idem.
+  - intros x y P Q.
+    rewrite assoc.
+    rewrite (comm x y).
+    rewrite <- (assoc y x x).
+    rewrite P.
+    rewrite (comm y x).
+    rewrite <- (assoc x y y).
+    apply (ap (x ∪) Q).
+Defined.
+
+Section relations.
+  Context `{Univalence}.
+
+  (** Membership of finite sets. *) 
+  Global Instance fset_member : forall A, hasMembership (FSet A) A.
+  Proof.
+    intros A a.
+    hrecursion.
+    - apply False_hp.
+    - apply (fun a' => merely(a = a')).
+    - apply lor.
+    - eauto with lattice_hints typeclass_instances.
+    - eauto with lattice_hints typeclass_instances.
+    - eauto with lattice_hints typeclass_instances.
+    - eauto with lattice_hints typeclass_instances.
+    - eauto with lattice_hints typeclass_instances.
+  Defined.
+
+  (** Subset relation of finite sets. *)
+  Global Instance fset_subset : forall A, hasSubset (FSet A).
+  Proof.
+    intros A X Y.
+    hrecursion X.
+    - apply Unit_hp.
+    - apply (fun a => a ∈ Y).
+    - intros X1 X2.
+      exists (prod X1 X2).
+      exact _.
+    - eauto with lattice_hints typeclass_instances. 
+    - eauto with lattice_hints typeclass_instances.
+    - intros.
+      apply path_trunctype ; apply prod_unit_l.
+    - intros.
+      apply path_trunctype ; apply prod_unit_r.
+    - eauto with lattice_hints typeclass_instances.
+  Defined.
+End relations.

FiniteSets/kuratowski/operations.v

@@ -1,27 +1,45 @@
-(* Operations on the [FSet A] for an arbitrary [A] *)
+(** Operations on the [FSet A] for an arbitrary [A] *)
 Require Import HoTT HitTactics.
-Require Import representations.definition disjunction lattice.
+Require Import kuratowski_sets monad_interface.
 
 Section operations.
-  Context `{Univalence}.
+  (** Monad operations. *)
-
+  Definition fset_fmap {A B : Type} : (A -> B) -> FSet A -> FSet B.
-  Global Instance fset_member : forall A, hasMembership (FSet A) A.
   Proof.
-    intros A a.
+    intro f.
     hrecursion.
-    - exists Empty.
+    - exact ∅.
-      exact _.
+    - apply (fun a => {|f a|}).
-    - intro a'.
+    - apply (∪).
-      exists (Trunc (-1) (a = a')).
+    - apply assoc.
-      exact _.
+    - apply comm.
-    - apply lor.
+    - apply nl.
-    - intros ; symmetry ; apply lor_assoc.
+    - apply nr.
-    - apply lor_commutative.
+    - apply (idem o f).
-    - apply lor_nl.
-    - apply lor_nr.
-    - intros ; apply lor_idem.
   Defined.
 
+  Global Instance fset_pure : hasPure FSet.
+  Proof.
+    split.
+    apply (fun _ a => {|a|}).
+  Defined.  
+
+  Global Instance fset_bind : hasBind FSet.
+  Proof.
+    split.
+    intros A.
+    hrecursion.
+    - exact ∅.
+    - exact idmap.
+    - apply (∪).
+    - apply assoc.
+    - apply comm.
+    - apply nl.
+    - apply nr.
+    - apply union_idem.
+  Defined.
+
+  (** Set-theoretical operations. *)
   Global Instance fset_comprehension : forall A, hasComprehension (FSet A) A.
   Proof.
     intros A P.
@@ -54,11 +72,12 @@ Section operations.
     - intro b.
       apply {|(a, b)|}.
     - apply (∪).
-    - intros X Y Z ; apply assoc.
+    - apply assoc.
-    - intros X Y ; apply comm.
+    - apply comm.
-    - intros ; apply nl.
+    - apply nl.
-    - intros ; apply nr.
+    - apply nr.
-    - intros ; apply idem.
+    - intros.
+      apply idem.
   Defined.
 
   Definition product {A B : Type} : FSet A -> FSet B -> FSet (A * B).
@@ -69,39 +88,13 @@ Section operations.
     - intro a.
       apply (single_product a Y).
     - apply (∪).
-    - intros ; apply assoc.
+    - apply assoc.
-    - intros ; apply comm.
+    - apply comm.
-    - intros ; apply nl.
+    - apply nl.
-    - intros ; apply nr.
+    - apply nr.
     - intros ; apply union_idem.
   Defined.
 
-  Global Instance fset_subset : forall A, hasSubset (FSet A).
-  Proof.
-    intros A X Y.
-    hrecursion X.
-    - exists Unit.
-      exact _.
-    - intros a.
-      apply (a ∈ Y).
-    - intros X1 X2.
-      exists (prod X1 X2).
-      exact _.
-    - intros.
-      apply path_trunctype ; apply equiv_prod_assoc.
-    - intros.
-      apply path_trunctype ; apply equiv_prod_symm.
-    - intros.
-      apply path_trunctype ; apply prod_unit_l.
-    - intros.
-      apply path_trunctype ; apply prod_unit_r.
-    - intros a'.
-      apply path_iff_hprop ; cbn.
-      * intros [p1 p2]. apply p1.
-      * intros p.
-        split ; apply p.
-  Defined.
-
   Local Ltac remove_transport
     := intros ; apply path_forall ; intro Z ; rewrite transport_arrow
        ; rewrite transport_const ; simpl.
@@ -111,7 +104,10 @@ Section operations.
       ; f_ap ; hott_simpl ; simple refine (path_sigma _ _ _ _ _)
       ; try (apply transport_const) ; try (apply path_ishprop).
 
-  Lemma separation (A B : Type) : forall (X : FSet A) (f : {a | a ∈ X} -> B), FSet B.
+  Context `{Univalence}.
+
+  (** Separation axiom for finite sets. *)
+  Definition separation (A B : Type) : forall (X : FSet A) (f : {a | a ∈ X} -> B), FSet B.
   Proof.
     hinduction.
     - intros f.
@@ -140,5 +136,48 @@ Section operations.
       rewrite <- (idem (Z (x; tr 1%path))).
       pointwise.
   Defined.
-
 End operations.
+
+Section operations_decidable.
+  Context {A : Type}.
+  Context {A_deceq : DecidablePaths A}.
+  Context `{Univalence}.
+
+  Global Instance isIn_decidable (a : A) : forall (X : FSet A),
+      Decidable (a ∈ X).
+  Proof.
+    hinduction ; try (intros ; apply path_ishprop).
+    - apply _.
+    - intros b.
+      destruct (dec (a = b)) as [p | np].
+      * apply (inl (tr p)).
+      * refine (inr(fun p => _)).
+        strip_truncations.
+        contradiction.
+    - apply _. 
+  Defined.
+
+  Global Instance fset_member_bool : hasMembership_decidable (FSet A) A.
+  Proof.
+    intros a X.
+    refine (if (dec a ∈ X) then true else false).
+  Defined.
+
+  Global Instance subset_decidable : forall (X Y : FSet A), Decidable (X ⊆ Y).
+  Proof.
+    hinduction ; try (intros ; apply path_ishprop).
+    - apply _.
+    - apply _. 
+    - unfold subset in *.
+      apply _.
+  Defined.
+
+  Global Instance fset_subset_bool : hasSubset_decidable (FSet A).
+  Proof.
+    intros X Y.
+    apply (if (dec (X ⊆ Y)) then true else false).
+  Defined.
+
+  Global Instance fset_intersection : hasIntersection (FSet A)
+    := fun X Y => {|X & (fun a => a ∈_d Y)|}.
+End operations_decidable.

FiniteSets/kuratowski/properties.v

@@ -1,14 +1,11 @@
 Require Import HoTT HitTactics.
-From fsets Require Import operations extensionality.
+Require Import kuratowski.extensionality kuratowski.operations kuratowski_sets.
-Require Export representations.definition disjunction.
+Require Import lattice_interface lattice_examples monad_interface.
-Require Import lattice.
 
-(* Lemmas relating operations to the membership predicate *)
+(** Lemmas relating operations to the membership predicate *)
-Section characterize_isIn.
+Section properties_membership.
-  Context {A : Type}.
+  Context {A : Type} `{Univalence}.
-  Context `{Univalence}.
 
-  (** isIn properties *)
   Definition empty_isIn (a: A) : a ∈ ∅ -> Empty := idmap.
 
   Definition singleton_isIn (a b: A) : a ∈ {|b|} -> Trunc (-1) (a = b) := idmap.
@@ -52,11 +49,8 @@ Section characterize_isIn.
            destruct Z ; assumption.
         ** intros ; apply tr ; right ; assumption.
   Defined.
-End characterize_isIn.
 
-Section product_isIn.
+  Context {B : Type}.
-  Context {A B : Type}.
-  Context `{Univalence}.
 
   Lemma isIn_singleproduct (a : A) (b : B) (c : A) : forall (Y : FSet B),
       (a, b) ∈ (single_product c Y) = land (BuildhProp (Trunc (-1) (a = c))) (b ∈ Y).
@@ -75,8 +69,10 @@ Section product_isIn.
     - intros X1 X2 HX1 HX2.
       apply path_iff_hprop ; rewrite ?union_isIn.
       * intros X.
+        cbn in *.
         strip_truncations.
-        destruct X as [H1 | H1] ; rewrite ?HX1, ?HX2 in H1 ; destruct H1 as [H1 H2].
+        destruct X as [H1 | H1] ; rewrite ?HX1, ?HX2 in H1
+        ; destruct H1 as [H1 H2].
         ** split.
            *** apply H1.
            *** apply (tr(inl H2)).
@@ -84,6 +80,7 @@ Section product_isIn.
            *** apply H1.
            *** apply (tr(inr H2)).
       * intros [H1 H2].
+        cbn in *.
         strip_truncations.
         apply tr.
         rewrite HX1, HX2.
@@ -102,7 +99,7 @@ Section product_isIn.
     - intros.
       apply isIn_singleproduct.
     - intros X1 X2 HX1 HX2.
-      rewrite (union_isIn (product X1 Y)).
+      cbn.
       rewrite HX1, HX2.
       apply path_iff_hprop ; rewrite ?union_isIn.
       * intros X.
@@ -116,7 +113,100 @@ Section product_isIn.
         ** left ; split ; assumption.
         ** right ; split ; assumption.
   Defined.
-End product_isIn.
+  
+  Lemma separation_isIn : forall (X : FSet A) (f : {a | a ∈ X} -> B) (b : B),
+      b ∈ (separation A B X f) = hexists (fun a : A => hexists (fun (p : a ∈ X) => f (a;p) = b)).
+  Proof.
+    hinduction ; try (intros ; apply path_forall ; intro ; apply path_ishprop).
+    - intros ; simpl.
+      apply path_iff_hprop ; try contradiction.
+      intros X.
+      strip_truncations.
+      destruct X as [a X].
+      strip_truncations.
+      destruct X as [p X].
+      assumption.
+    - intros.
+      apply path_iff_hprop ; simpl.
+      * intros ; strip_truncations.
+        apply tr.
+        exists a.
+        apply tr.
+        exists (tr idpath).
+        apply X^.
+      * intros X ; strip_truncations.
+        destruct X as [a0 X].
+        strip_truncations.
+        destruct X as [X q].
+        simple refine (Trunc_ind _ _ X).
+        intros p.
+        apply tr.
+        rewrite <- q.
+        f_ap.
+        simple refine (path_sigma _ _ _ _ _).
+        ** apply p.
+        ** apply path_ishprop.
+    - intros X1 X2 HX1 HX2 f b.
+      pose (fX1 := fun Z : {a : A & a ∈ X1} => f (pr1 Z;tr (inl (pr2 Z)))).
+      pose (fX2 := fun Z : {a : A & a ∈ X2} => f (pr1 Z;tr (inr (pr2 Z)))).
+      specialize (HX1 fX1 b).
+      specialize (HX2 fX2 b).
+      apply path_iff_hprop.
+      * intros X.
+        cbn in *.
+        strip_truncations.
+        destruct X as [X | X].
+        ** rewrite HX1 in X.
+           strip_truncations.
+           destruct X as [a Ha].
+           apply tr.
+           exists a.
+           strip_truncations.
+           destruct Ha as [p pa].
+           apply tr.
+           exists (tr(inl p)).
+           rewrite <- pa.
+           reflexivity.
+        ** rewrite HX2 in X.
+           strip_truncations.
+           destruct X as [a Ha].
+           apply tr.
+           exists a.
+           strip_truncations.
+           destruct Ha as [p pa].
+           apply tr.
+           exists (tr(inr p)).
+           rewrite <- pa.
+           reflexivity.
+      * intros.
+        strip_truncations.
+        destruct X as [a X].
+        strip_truncations.
+        destruct X as [Ha p].
+        cbn.
+        simple refine (Trunc_ind _ _ Ha) ; intros [Ha1 | Ha2].
+        ** refine (tr(inl _)).
+           rewrite HX1.
+           apply tr.
+           exists a.
+           apply tr.
+           exists Ha1.
+           rewrite <- p.
+           unfold fX1.
+           repeat f_ap.
+           apply path_ishprop.
+        ** refine (tr(inr _)).
+           rewrite HX2.
+           apply tr.
+           exists a.
+           apply tr.
+           exists Ha2.
+           rewrite <- p.
+           unfold fX2.
+           repeat f_ap.
+           apply path_ishprop.
+  Defined.
+End properties_membership.
 
 Ltac simplify_isIn :=
   repeat (rewrite union_isIn
@@ -127,10 +217,9 @@ Ltac toHProp :=
   apply fset_ext ; intros ;
   simplify_isIn ; eauto with lattice_hints typeclass_instances.
 
-(* Other properties *)
+(** [FSet A] is a join semilattice. *)
-Section properties.
+Section fset_join_semilattice.
   Context {A : Type}.
-  Context `{Univalence}.
 
   Instance: bottom(FSet A).
   Proof.
@@ -146,10 +235,223 @@ Section properties.
 
   Global Instance joinsemilattice_fset : JoinSemiLattice (FSet A).
   Proof.
-    split ; toHProp.
+    split.
+    - intros ? ?.
+      apply comm.
+    - intros ? ? ?.
+      apply (assoc _ _ _)^.
+    - intros ?.
+      apply union_idem.
+    - intros x.
+      apply nl.
+    - intros ?.
+      apply nr.
+  Defined.
+End fset_join_semilattice.
+
+(* Lemmas relating operations to the membership predicate *)
+Section properties_membership_decidable.
+  Context {A : Type} `{DecidablePaths A} `{Univalence}.
+
+  Lemma ext : forall (S T : FSet A), (forall a, a ∈_d S = a ∈_d T) -> S = T.
+  Proof.
+    intros X Y H2.
+    apply fset_ext.
+    intro a.
+    specialize (H2 a).
+    unfold member_dec, fset_member_bool, dec in H2.
+    destruct (isIn_decidable a X) ; destruct (isIn_decidable a Y).
+    - apply path_iff_hprop ; intro ; assumption.
+    - contradiction (true_ne_false).
+    - contradiction (true_ne_false) ; apply H2^.
+    - apply path_iff_hprop ; intro ; contradiction.
   Defined.
 
-  (** comprehension properties *)
+  Lemma empty_isIn_d (a : A) :
+    a ∈_d ∅ = false.
+  Proof.
+    reflexivity.
+  Defined.
+
+  Lemma singleton_isIn_d (a b : A) :
+    a ∈ {|b|} -> a = b.
+  Proof.
+    intros. strip_truncations. assumption.
+  Defined.
+
+  Lemma singleton_isIn_d_true (a b : A) (p : a = b) :
+    a ∈_d {|b|} = true.
+  Proof.
+    unfold member_dec, fset_member_bool, dec.
+    destruct (isIn_decidable a {|b|}) as [n | n] .
+    - reflexivity.
+    - simpl in n.
+      contradiction (n (tr p)).
+  Defined.
+
+  Lemma singleton_isIn_d_aa (a : A) :
+    a ∈_d {|a|} = true.
+  Proof.
+    apply singleton_isIn_d_true ; reflexivity.
+  Defined.
+
+  Lemma singleton_isIn_d_false (a b : A) (p : a <> b) :
+    a ∈_d {|b|} = false.
+  Proof.
+    unfold member_dec, fset_member_bool, dec in *.
+    destruct (isIn_decidable a {|b|}).
+    - simpl in t.
+      strip_truncations.
+      contradiction.
+    - reflexivity.
+  Defined.
+
+  Lemma union_isIn_d (X Y : FSet A) (a : A) :
+    a ∈_d (X ∪ Y) = orb (a ∈_d X) (a ∈_d Y).
+  Proof.
+    unfold member_dec, fset_member_bool, dec.
+    simpl.
+    destruct (isIn_decidable a X) ; destruct (isIn_decidable a Y) ; reflexivity.
+  Defined.
+
+  Lemma comprehension_isIn_d (Y : FSet A) (ϕ : A -> Bool) (a : A) :
+    a ∈_d {|Y & ϕ|} = andb (a ∈_d Y) (ϕ a).
+  Proof.
+    unfold member_dec, fset_member_bool, dec ; simpl.
+    destruct (isIn_decidable a {|Y & ϕ|}) as [t | t]
+    ; destruct (isIn_decidable a Y) as [n | n] ; rewrite comprehension_isIn in t
+    ; destruct (ϕ a) ; try reflexivity ; try contradiction
+    ; try (contradiction (n t)) ; contradiction (t n).
+  Defined.
+
+  Lemma intersection_isIn_d (X Y: FSet A) (a : A) :
+    a ∈_d (intersection X Y) = andb (a ∈_d X) (a ∈_d Y).
+  Proof.
+    apply comprehension_isIn_d.
+  Defined.
+End properties_membership_decidable.
+
+(* Some suporting tactics *)
+Ltac simplify_isIn_d :=
+  repeat (rewrite union_isIn_d
+        || rewrite singleton_isIn_d_aa
+        || rewrite intersection_isIn_d
+        || rewrite comprehension_isIn_d).
+
+Ltac toBool :=
+  repeat intro;
+  apply ext ; intros ;
+  simplify_isIn_d ; eauto with bool_lattice_hints typeclass_instances.
+
+(** If `A` has decidable equality, then `FSet A` is a lattice *) 
+Section set_lattice.
+  Context {A : Type}.
+  Context {A_deceq : DecidablePaths A}.
+  Context `{Univalence}.
+
+  Instance fset_max : maximum (FSet A).
+  Proof.
+    intros x y.
+    apply (x ∪ y).
+  Defined.
+
+  Instance fset_min : minimum (FSet A).
+  Proof.
+    intros x y.
+    apply (x ∩ y).
+  Defined.
+
+  Instance fset_bot : bottom (FSet A).
+  Proof.
+    unfold bottom.
+    apply ∅.
+  Defined.
+
+  Instance lattice_fset : Lattice (FSet A).
+  Proof.
+    split ; toBool.
+  Defined.
+End set_lattice.
+
+(** If `A` has decidable equality, then so has `FSet A`. *)
+Section dec_eq.
+  Context {A : Type} `{DecidablePaths A} `{Univalence}.
+
+  Instance fsets_dec_eq : DecidablePaths (FSet A).
+  Proof.
+    intros X Y.
+    apply (decidable_equiv' ((Y ⊆ X) * (X ⊆ Y)) (eq_subset X Y)^-1).
+    apply decidable_prod.
+  Defined.
+End dec_eq.
+
+(** [FSet] is a (strong and stable) finite powerset monad *)
+Section monad_fset.
+  Context `{Funext}.
+
+  Global Instance fset_functorish : Functorish FSet.
+  Proof.
+    simple refine (Build_Functorish _ _ _).
+    - intros ? ? f.
+      apply (fset_fmap f).
+    - intros A.
+      apply path_forall.
+      intro x.
+      hinduction x
+      ; try (intros ; f_ap)
+      ; try (intros ; apply path_ishprop).
+  Defined.
+
+  Global Instance fset_functor : Functor FSet.
+  Proof.
+    split.
+    intros.
+    apply path_forall.
+    intro x.
+    hrecursion x
+    ; try (intros ; f_ap)
+    ; try (intros ; apply path_ishprop).
+  Defined.
+
+  Global Instance fset_monad : Monad FSet.
+  Proof.
+    split.
+    - intros.
+      apply path_forall.
+      intro X.
+      hrecursion X ; try (intros; f_ap) ;
+        try (intros; apply path_ishprop).
+    - intros.
+      apply path_forall.
+      intro X.
+      hrecursion X ; try (intros; f_ap) ;
+        try (intros; apply path_ishprop).
+    - intros.
+      apply path_forall.
+      intro X.
+      hrecursion X ; try (intros; f_ap) ;
+        try (intros; apply path_ishprop).
+  Defined.
+
+  Lemma fmap_isIn `{Univalence} {A B : Type} (f : A -> B) (a : A) (X : FSet A) :
+    a ∈ X -> (f a) ∈ (fmap FSet f X).
+  Proof.
+    hinduction X; try (intros; apply path_ishprop).
+    - apply idmap.
+    - intros b Hab; strip_truncations.
+      apply (tr (ap f Hab)).
+    - intros X0 X1 HX0 HX1 Ha.
+      strip_truncations. apply tr.
+      destruct Ha as [Ha | Ha].
+      + left. by apply HX0.
+      + right. by apply HX1.
+  Defined.
+End monad_fset.
+
+(** comprehension properties *)
+Section comprehension_properties.
+  Context {A : Type} `{Univalence}.
+
   Lemma comprehension_false : forall (X : FSet A), {|X & fun _ => false|} = ∅.
   Proof.
     toHProp.
@@ -176,6 +478,11 @@ Section properties.
   Proof.
     toHProp.
   Defined.
+End comprehension_properties.
+
+(** For [FSet A] we have mere choice. *)
+Section mere_choice.
+  Context {A : Type} `{Univalence}.
 
   Local Ltac solve_mc :=
     repeat (let x := fresh in intro x ; try(destruct x))
@@ -219,98 +526,4 @@ Section properties.
     - solve_mc.
     - solve_mc.
   Defined.
-
+End mere_choice.
-  Lemma separation_isIn (B : Type) : forall (X : FSet A) (f : {a | a ∈ X} -> B) (b : B),
-      b ∈ (separation A B X f) = hexists (fun a : A => hexists (fun (p : a ∈ X) => f (a;p) = b)).
-  Proof.
-    hinduction ; try (intros ; apply path_forall ; intro ; apply path_ishprop).
-    - intros ; simpl.
-      apply path_iff_hprop ; try contradiction.
-      intros X.
-      strip_truncations.
-      destruct X as [a X].
-      strip_truncations.
-      destruct X as [p X].
-      assumption.
-    - intros.
-      apply path_iff_hprop ; simpl.
-      * intros ; strip_truncations.
-        apply tr.
-        exists a.
-        apply tr.
-        exists (tr idpath).
-        apply X^.
-      * intros X ; strip_truncations.
-        destruct X as [a0 X].
-        strip_truncations.
-        destruct X as [X q].
-        simple refine (Trunc_ind _ _ X).
-        intros p.
-        apply tr.
-        rewrite <- q.
-        f_ap.
-        simple refine (path_sigma _ _ _ _ _).
-        ** apply p.
-        ** apply path_ishprop.
-    - intros X1 X2 HX1 HX2 f b.
-      pose (fX1 := fun Z : {a : A & a ∈ X1} => f (pr1 Z;tr (inl (pr2 Z)))).
-      pose (fX2 := fun Z : {a : A & a ∈ X2} => f (pr1 Z;tr (inr (pr2 Z)))).
-      specialize (HX1 fX1 b).
-      specialize (HX2 fX2 b).
-      apply path_iff_hprop.
-      * intros X.
-        rewrite union_isIn in X.
-        strip_truncations.
-        destruct X as [X | X].
-        ** rewrite HX1 in X.
-           strip_truncations.
-           destruct X as [a Ha].
-           apply tr.
-           exists a.
-           strip_truncations.
-           destruct Ha as [p pa].
-           apply tr.
-           exists (tr(inl p)).
-           rewrite <- pa.
-           reflexivity.
-        ** rewrite HX2 in X.
-           strip_truncations.
-           destruct X as [a Ha].
-           apply tr.
-           exists a.
-           strip_truncations.
-           destruct Ha as [p pa].
-           apply tr.
-           exists (tr(inr p)).
-           rewrite <- pa.
-           reflexivity.
-      * intros.
-        strip_truncations.
-        destruct X as [a X].
-        strip_truncations.
-        destruct X as [Ha p].
-        rewrite union_isIn.
-        simple refine (Trunc_ind _ _ Ha) ; intros [Ha1 | Ha2].
-        ** refine (tr(inl _)).
-           rewrite HX1.
-           apply tr.
-           exists a.
-           apply tr.
-           exists Ha1.
-           rewrite <- p.
-           unfold fX1.
-           repeat f_ap.
-           apply path_ishprop.
-        ** refine (tr(inr _)).
-           rewrite HX2.
-           apply tr.
-           exists a.
-           apply tr.
-           exists Ha2.
-           rewrite <- p.
-           unfold fX2.
-           repeat f_ap.
-           apply path_ishprop.
-  Defined.
-
-End properties.

FiniteSets/lattice.v

@@ -1,205 +0,0 @@
-(* Typeclass for lattices *)
-Require Import HoTT.
-Require Import notation.
-
-Section binary_operation.
-  Variable A : Type.
-
-  Class maximum :=
-    max_L : operation A.
-
-  Class minimum :=
-    min_L : operation A.
-
-  Class bottom :=
-    empty : A.
-End binary_operation.
-
-Arguments max_L {_} {_} _.
-Arguments min_L {_} {_} _.
-Arguments empty {_}.
-
-Section JoinSemiLattice.
-  Variable A : Type.
-  Context {max_L : maximum A} {empty_L : bottom A}.
-
-  Class JoinSemiLattice :=
-    {
-      commutative_max_js :> Commutative max_L ;
-      associative_max_js :> Associative max_L ;
-      idempotent_max_js :> Idempotent max_L ;
-      neutralL_max_js :> NeutralL max_L empty_L ;
-      neutralR_max_js :> NeutralR max_L empty_L ;
-    }.
-End JoinSemiLattice.
-
-Arguments JoinSemiLattice _ {_} {_}.
-
-Create HintDb joinsemilattice_hints.
-Hint Resolve associativity : joinsemilattice_hints.
-Hint Resolve (associativity _ _ _)^ : joinsemilattice_hints.
-Hint Resolve commutative : joinsemilattice_hints.
-Hint Resolve idempotency : joinsemilattice_hints.
-Hint Resolve neutralityL : joinsemilattice_hints.
-Hint Resolve neutralityR : joinsemilattice_hints.
-
-Section Lattice.
-  Variable A : Type.
-  Context {max_L : maximum A} {min_L : minimum A} {empty_L : bottom A}.
-
-  Class Lattice :=
-    {
-      commutative_min :> Commutative min_L ;
-      commutative_max :> Commutative max_L ;
-      associative_min :> Associative min_L ;
-      associative_max :> Associative max_L ;
-      idempotent_min :> Idempotent min_L ;
-      idempotent_max :> Idempotent max_L ;
-      neutralL_max :> NeutralL max_L empty_L ;
-      neutralR_max :> NeutralR max_L empty_L ;
-      absorption_min_max :> Absorption min_L max_L ;
-      absorption_max_min :> Absorption max_L min_L
-    }.
-End Lattice.
-
-Arguments Lattice _ {_} {_} {_}.
-
-Create HintDb lattice_hints.
-Hint Resolve associativity : lattice_hints.
-Hint Resolve (associativity _ _ _)^ : lattice_hints.
-Hint Resolve commutative : lattice_hints.
-Hint Resolve absorb : lattice_hints.
-Hint Resolve idempotency : lattice_hints.
-Hint Resolve neutralityL : lattice_hints.
-Hint Resolve neutralityR : lattice_hints.
-
-Section BoolLattice.
-
-  Ltac solve_bool :=
-    let x := fresh in
-    repeat (intro x ; destruct x)
-    ; compute
-    ; auto
-    ; try contradiction.
-
-  Instance maximum_bool : maximum Bool := orb.
-  Instance minimum_bool : minimum Bool := andb.
-  Instance bottom_bool : bottom Bool := false.
-
-  Global Instance lattice_bool : Lattice Bool.
-  Proof.
-    split ; solve_bool.
-  Defined.
-
-  Definition and_true : forall b, andb b true = b.
-  Proof.
-    solve_bool.
-  Defined.
-
-  Definition and_false : forall b, andb b false = false.
-  Proof.
-    solve_bool.
-  Defined.
-
-  Definition dist₁ : forall b₁ b₂ b₃,
-      andb b₁ (orb b₂ b₃) = orb (andb b₁ b₂) (andb b₁ b₃).
-  Proof.
-    solve_bool.
-  Defined.
-
-  Definition dist₂ : forall b₁ b₂ b₃,
-      orb b₁ (andb b₂ b₃) = andb (orb b₁ b₂) (orb b₁ b₃).
-  Proof.
-    solve_bool.
-  Defined.
-
-  Definition max_min : forall b₁ b₂,
-      orb (andb b₁ b₂) b₁ = b₁.
-  Proof.
-    solve_bool.
-  Defined.
-
-End BoolLattice.
-
-Section fun_lattice.
-  Context {A B : Type}.
-  Context `{Lattice B}.
-  Context `{Funext}.
-
-  Global Instance max_fun : maximum (A -> B) :=
-    fun (f g : A -> B) (a : A) => max_L0 (f a) (g a).
-
-  Global Instance min_fun : minimum (A -> B) :=
-    fun (f g : A -> B) (a : A) => min_L0 (f a) (g a).
-
-  Global Instance bot_fun : bottom (A -> B)
-    := fun _ => empty_L.
-
-  Ltac solve_fun :=
-    compute ; intros ; apply path_forall ; intro ;
-    eauto with lattice_hints typeclass_instances.
-
-  Global Instance lattice_fun : Lattice (A -> B).
-  Proof.
-    split ; solve_fun.
-  Defined.
-
-End fun_lattice.
-
-Section sub_lattice.
-  Context {A : Type} {P : A -> hProp}.
-  Context `{Lattice A}.
-  Context {Hmax : forall x y, P x -> P y -> P (max_L0 x y)}.
-  Context {Hmin : forall x y, P x -> P y -> P (min_L0 x y)}.
-  Context {Hbot : P empty_L}.
-
-  Definition AP : Type := sig P.
-
-  Instance botAP : bottom AP := (empty_L ; Hbot).
-
-  Instance maxAP : maximum AP :=
-    fun x y =>
-      match x, y with
-      | (a ; pa), (b ; pb) => (max_L0 a b ; Hmax a b pa pb)
-      end.
-
-  Instance minAP : minimum AP :=
-    fun x y =>
-      match x, y with
-      | (a ; pa), (b ; pb) => (min_L0 a b ; Hmin a b pa pb)
-      end.
-
-  Instance hprop_sub : forall c, IsHProp (P c).
-  Proof.
-    apply _.
-  Defined.
-
-  Ltac solve_sub :=
-    let x := fresh in
-    repeat (intro x ; destruct x)
-    ; simple refine (path_sigma _ _ _ _ _)
-    ; simpl
-    ; try (apply hprop_sub)
-    ; eauto 3 with lattice_hints typeclass_instances.
-
-  Global Instance lattice_sub : Lattice AP.
-  Proof.
-    split ; solve_sub.
-  Defined.
-
-End sub_lattice.
-
-Create HintDb bool_lattice_hints.
-Hint Resolve associativity : bool_lattice_hints.
-Hint Resolve (associativity _ _ _)^ : bool_lattice_hints.
-Hint Resolve commutative : bool_lattice_hints.
-Hint Resolve absorb : bool_lattice_hints.
-Hint Resolve idempotency : bool_lattice_hints.
-Hint Resolve neutralityL : bool_lattice_hints.
-Hint Resolve neutralityR : bool_lattice_hints.
-
-Hint Resolve
-     associativity
-     and_true and_false
-     dist₁ dist₂ max_min
- : bool_lattice_hints.

FiniteSets/list_representation/isomorphism.v

@@ -1,15 +1,16 @@
 (* The representations [FSet A] and [FSetC A] are isomorphic for every A *)
 Require Import HoTT HitTactics.
-From representations Require Import cons_repr definition.
+Require Import list_representation list_representation.operations
-From fsets Require Import operations_cons_repr properties_cons_repr.
+        list_representation.properties.
+Require Import kuratowski.kuratowski_sets.
 
 Section Iso.
-
   Context {A : Type}.
   Context `{Univalence}.
 
   Definition dupl' (a : A) (X : FSet A) :
     {|a|} ∪ {|a|} ∪ X = {|a|} ∪ X := assoc _ _ _ @ ap (∪ X) (idem _).
+  
   Definition comm' (a b : A) (X : FSet A) :
     {|a|} ∪ {|b|} ∪ X = {|b|} ∪ {|a|} ∪ X :=
     assoc _ _ _ @ ap (∪ X) (comm _ _) @ (assoc _ _ _)^.
@@ -110,18 +111,18 @@ Section Iso.
     simple refine (FSetC_ind A (fun Z => P (FSetC_to_FSet Z)) _ _ _ _ _ (FSet_to_FSetC X)); simpl.
     - apply Pempt.
     - intros a Y HY. by apply Pcons.
-    - intros a Y PY. cbn.
+    - intros a Y PY.
       refine (_ @ (Pdupl _ _ _)).
       etransitivity.
       { apply (transport_compose _ FSetC_to_FSet (dupl a Y)). }
       refine (ap (fun z => transport P z _) _).
-      apply FSetC_rec_beta_dupl.
+      apply path_ishprop.
     - intros a b Y PY. cbn.
       refine (_ @ (Pcomm _ _ _ _)).
       etransitivity.
       { apply (transport_compose _ FSetC_to_FSet (FSetC.comm a b Y)). }
       refine (ap (fun z => transport P z _) _).
-      apply FSetC_rec_beta_comm.
+      apply path_ishprop.
   Defined.
 
   Theorem FSet_cons_ind_beta_empty (P : FSet A -> Type)
@@ -133,7 +134,9 @@ Section Iso.
     (Pcomm : forall (a b : A) (X : FSet A) (px : P X),
        transport P (comm' a b X) (Pcons a _ (Pcons b X px)) = Pcons b _ (Pcons a X px)) :
     FSet_cons_ind P Pset Pempt Pcons Pdupl Pcomm ∅ = Pempt.
-  Proof. by compute. Defined.
+  Proof.
+      by compute.
+  Defined.
 
   (* TODO *)
   (* Theorem FSet_cons_ind_beta_cons (P : FSet A -> Type)  *)

FiniteSets/list_representation/list_representation.v

@@ -0,0 +1,84 @@
+(** Definition of Finite Sets as via lists. *)
+Require Import HoTT HitTactics.
+Require Export set_names.
+
+Module Export FSetC.
+
+  Section FSetC.
+    Private Inductive FSetC (A : Type) : Type :=
+    | Nil : FSetC A
+    | Cns : A ->  FSetC A -> FSetC A.
+
+    Global Instance fset_empty : forall A,hasEmpty (FSetC A) := Nil.
+
+    Variable A : Type.
+    Arguments Cns {_} _ _.
+    Infix ";;" := Cns (at level 8, right associativity).
+
+    Axiom dupl : forall (a : A) (x : FSetC A),
+        a ;; a ;; x = a ;; x.
+
+    Axiom comm : forall (a b : A) (x : FSetC A),
+        a ;; b ;; x = b ;; a ;; x.
+
+    Axiom trunc : IsHSet (FSetC A).
+  End FSetC.
+
+  Arguments Cns {_} _ _.
+  Arguments dupl {_} _ _.
+  Arguments comm {_} _ _ _.
+
+  Infix ";;" := Cns (at level 8, right associativity).
+
+  Section FSetC_induction.
+    Variable (A : Type)
+             (P : FSetC A -> Type)
+             (H :  forall x : FSetC A, IsHSet (P x))
+             (eP : P ∅)
+             (cnsP : forall (a:A) (x: FSetC A), P x -> P (a ;; x))
+             (duplP : forall (a: A) (x: FSetC A) (px : P x),
+	         dupl a x # cnsP a (a;;x) (cnsP a x px) = cnsP a x px)
+             (commP : forall (a b: A) (x: FSetC A) (px: P x),
+		 comm a b x # cnsP a (b;;x) (cnsP b x px) =
+		 cnsP b (a;;x) (cnsP a x px)).
+
+    (* Induction principle *)
+    Fixpoint FSetC_ind
+             (x : FSetC A)
+             {struct x}
+      : P x
+      := (match x return _ -> _ -> _ -> P x with
+          | Nil => fun _ => fun _ => fun _  => eP
+          | a ;; y => fun _ => fun _ => fun _ => cnsP a y (FSetC_ind y)
+          end) H duplP commP.
+  End FSetC_induction.
+
+  Section FSetC_recursion.
+    Variable (A : Type)
+             (P : Type)
+             (H : IsHSet P)
+             (nil : P)
+             (cns :  A -> P -> P)
+             (duplP : forall (a: A) (x: P), cns a (cns a x) = (cns a x))
+             (commP : forall (a b: A) (x: P), cns a (cns b x) = cns b (cns a x)).
+
+    (* Recursion principle *)
+    Definition FSetC_rec : FSetC A -> P.
+    Proof.
+      simple refine (FSetC_ind _ _ _ _ _  _ _ );
+        try (intros; simple refine ((transport_const _ _) @ _ ));  cbn.
+      - apply nil.
+      - apply (fun a => fun _ => cns a).
+      - apply duplP.
+      - apply commP.
+    Defined.
+  End FSetC_recursion.
+
+  Instance FSetC_recursion A : HitRecursion (FSetC A) :=
+    {
+      indTy := _; recTy := _;
+      H_inductor := FSetC_ind A; H_recursor := FSetC_rec A
+    }.
+End FSetC.
+
+Infix ";;" := Cns (at level 8, right associativity).

FiniteSets/list_representation/operations.v

@@ -1,6 +1,6 @@
-(* Operations on [FSetC A] *)
+(** Operations on [FSetC A] *)
 Require Import HoTT HitTactics.
-Require Import representations.cons_repr.
+Require Import list_representation.
 
 Section operations.
   Global Instance fsetc_union : forall A, hasUnion (FSetC A).

FiniteSets/list_representation/properties.v

@@ -1,7 +1,6 @@
-(* Properties of the operations on [FSetC A] *)
+(** Properties of the operations on [FSetC A] *)
 Require Import HoTT HitTactics.
-Require Import representations.cons_repr.
+Require Import list_representation list_representation.operations.
-From fsets Require Import operations_cons_repr.
 
 Section properties.
   Context {A : Type}.
@@ -42,21 +41,18 @@ Section properties.
     forall (x1 x2: FSetC A), x1 ∪ x2 = x2 ∪ x1.
   Proof.
     hinduction ;  try (intros ; apply path_forall ; intro ; apply set_path2).
-    - intros. symmetry. apply append_nr.
+    - intros.
+      apply (append_nr _)^.
     - intros a x1 HR x2.
-      etransitivity.
+      refine (ap (fun y => a;;y) (HR x2) @ _).
-      apply (ap (fun y => a;;y) (HR x2)).
+      refine (append_singleton _ _ @ _).
-      transitivity  ((x2 ∪ x1) ∪ (a;;∅)).
+      refine ((append_assoc _ _ _)^ @ _).
-      + apply append_singleton.
+      refine (ap (x2 ∪) (append_singleton _ _)^).
-      + etransitivity.
-    	* symmetry. apply append_assoc.
-    	* simple refine (ap (x2 ∪) (append_singleton _ _)^).
   Defined.
 
   Lemma singleton_idem: forall (a: A),
       {|a|} ∪ {|a|} = {|a|}.
   Proof.
-    unfold singleton.
     intro.
     apply dupl.
   Defined.

FiniteSets/misc/T.v

@@ -0,0 +1,62 @@
+(** Merely decidable equality implies LEM *)
+Require Import HoTT HitTactics prelude.
+
+Section TR.
+  Context `{Univalence}.
+  Variable A : hProp.
+
+  Definition T := Unit + Unit.
+
+  Definition R (x y : T) : hProp :=
+    match x, y with
+    | inl tt, inl tt => Unit_hp
+    | inl tt, inr tt => A
+    | inr tt, inl tt => A
+    | inr tt, inr tt => Unit_hp
+    end.
+
+  Global Instance R_refl : Reflexive R.
+  Proof.
+    intro x ; destruct x as [[ ] | [ ]] ; apply tt.
+  Defined.
+  
+  Global Instance R_sym : Symmetric R.
+  Proof.
+    repeat (let x := fresh in intro x ; destruct x as [[ ] | [ ]])
+    ; auto ; apply tt.
+  Defined.
+  
+  Global Instance R_trans : Transitive R.
+  Proof.
+    repeat (let x := fresh in intro x ; destruct x as [[ ] | [ ]]) ; intros
+    ; auto ; apply tt.
+  Defined.
+
+  Definition TR : Type := quotient R.
+  Definition TR_zero : TR := class_of R (inl tt).
+  Definition TR_one : TR := class_of R (inr tt).
+
+  Definition equiv_pathspace_T : (TR_zero = TR_one) = (R (inl tt) (inr tt))
+    := path_universe (sets_exact R (inl tt) (inr tt)).
+
+  Global Instance quotientB_recursion : HitRecursion TR :=
+    {
+      indTy := _;
+      recTy :=
+        forall (P : Type) (HP: IsHSet P) (u : T -> P),
+          (forall x y : T, R x y -> u x = u y) -> TR -> P;
+      H_inductor := quotient_ind R ;
+      H_recursor := @quotient_rec _ R _
+    }.
+End TR.
+
+Theorem merely_dec `{Univalence} : (forall (A : Type) (a b : A), hor (a = b) (~a = b))
+                                   ->
+                                   forall (A : hProp), A + (~A).
+Proof.
+  intros X A.
+  specialize (X (TR A) (TR_zero A) (TR_one A)).
+  rewrite equiv_pathspace_T in X.
+  strip_truncations.
+  apply X.
+Defined.

FiniteSets/misc/bad.v

@@ -0,0 +1,288 @@
+(* This is a /bad/ definition of FSets, without the 0-truncation.
+   Here we show that the resulting type is not an h-set. *)
+Require Import HoTT HitTactics.
+Require Import set_names.
+
+Module Export FSet.
+  
+  Section FSet.
+    Private Inductive FSet (A : Type): Type :=
+    | E : FSet A
+    | L : A -> FSet A
+    | U : FSet A -> FSet A -> FSet A.
+
+    Global Instance fset_empty : forall A, hasEmpty (FSet A) := E.
+    Global Instance fset_singleton : forall A, hasSingleton (FSet A) A := L.
+    Global Instance fset_union : forall A, hasUnion (FSet A) := U.
+
+    Variable A : Type.
+
+    Axiom assoc : forall (x y z : FSet A),
+        x ∪ (y ∪ z) = (x ∪ y) ∪ z.
+
+    Axiom comm : forall (x y : FSet A),
+        x ∪ y = y ∪ x.
+
+    Axiom nl : forall (x : FSet A),
+        ∅ ∪ x = x.
+
+    Axiom nr : forall (x : FSet A),
+        x ∪ ∅ = x.
+
+    Axiom idem : forall (x : A),
+        {|x|} ∪ {|x|} = {|x|}.
+
+  End FSet.
+
+  Arguments assoc {_} _ _ _.
+  Arguments comm {_} _ _.
+  Arguments nl {_} _.
+  Arguments nr {_} _.
+  Arguments idem {_} _.
+
+  Section FSet_induction.
+    Variable A: Type.
+    Variable  (P : FSet A -> Type).
+    Variable  (eP : P ∅).
+    Variable  (lP : forall a: A, P {|a |}).
+    Variable  (uP : forall (x y: FSet A), P x -> P y -> P (x ∪ y)).
+    Variable  (assocP : forall (x y z : FSet A) 
+                               (px: P x) (py: P y) (pz: P z),
+                  assoc x y z #
+                        (uP x (y ∪ z) px (uP y z py pz)) 
+                  = 
+                  (uP (x ∪ y) z (uP x y px py) pz)).
+    Variable  (commP : forall (x y: FSet A) (px: P x) (py: P y),
+                  comm x y #
+                       uP x y px py = uP y x py px).
+    Variable  (nlP : forall (x : FSet A) (px: P x), 
+                  nl x # uP ∅ x eP px = px).
+    Variable  (nrP : forall (x : FSet A) (px: P x), 
+                  nr x # uP x ∅ px eP = px).
+    Variable  (idemP : forall (x : A), 
+                  idem x # uP {|x|} {|x|} (lP x) (lP x) = lP x).
+
+    (* Induction principle *)
+    Fixpoint FSet_ind
+             (x : FSet A)
+             {struct x}
+      : P x
+      := (match x return _ -> _ -> _ -> _ -> _ -> P x with
+          | E => fun _ _ _ _ _ => eP
+          | L a => fun _ _ _ _ _ => lP a
+          | U y z => fun _ _ _ _ _ => uP y z (FSet_ind y) (FSet_ind z)
+          end) assocP commP nlP nrP idemP.
+
+    Axiom FSet_ind_beta_assoc : forall (x y z : FSet A),
+        apD FSet_ind (assoc x y z) =
+        (assocP x y z (FSet_ind x) (FSet_ind y) (FSet_ind z)).
+
+    Axiom FSet_ind_beta_comm : forall (x y : FSet A),
+        apD FSet_ind (comm x y) = commP x y (FSet_ind x) (FSet_ind y).
+
+    Axiom FSet_ind_beta_nl : forall (x : FSet A),
+        apD FSet_ind (nl x) = nlP x (FSet_ind x).
+
+    Axiom FSet_ind_beta_nr : forall (x : FSet A),
+        apD FSet_ind (nr x) = nrP x (FSet_ind x).
+
+    Axiom FSet_ind_beta_idem : forall (x : A), apD FSet_ind (idem x) = idemP x.
+  End FSet_induction.
+
+  Section FSet_recursion.
+
+    Variable A : Type.
+    Variable P : Type.
+    Variable e : P.
+    Variable l : A -> P.
+    Variable u : P -> P -> P.
+    Variable assocP : forall (x y z : P), u x (u y z) = u (u x y) z.
+    Variable commP : forall (x y : P), u x y = u y x.
+    Variable nlP : forall (x : P), u e x = x.
+    Variable nrP : forall (x : P), u x e = x.
+    Variable idemP : forall (x : A), u (l x) (l x) = l x.
+
+    Definition FSet_rec : FSet A -> P.
+    Proof.
+      simple refine (FSet_ind A _ _ _ _ _ _ _ _ _) ; try (intros ; simple refine ((transport_const _ _) @ _)) ; cbn.
+      - apply e.
+      - apply l.
+      - intros x y ; apply u.
+      - apply assocP.
+      - apply commP.
+      - apply nlP.
+      - apply nrP.
+      - apply idemP.
+    Defined.
+
+    Definition FSet_rec_beta_assoc : forall (x y z : FSet A),
+        ap FSet_rec (assoc x y z) 
+        =
+        assocP (FSet_rec x) (FSet_rec y) (FSet_rec z).
+    Proof.
+      intros.
+      unfold FSet_rec.
+      eapply (cancelL (transport_const (assoc x y z) _)).
+      simple refine ((apD_const _ _)^ @ _).
+      apply FSet_ind_beta_assoc.
+    Defined.
+
+    Definition FSet_rec_beta_comm : forall (x y : FSet A),
+        ap FSet_rec (comm x y) 
+        =
+        commP (FSet_rec x) (FSet_rec y).
+    Proof.
+      intros.
+      unfold FSet_rec.
+      eapply (cancelL (transport_const (comm x y) _)).
+      simple refine ((apD_const _ _)^ @ _).
+      apply FSet_ind_beta_comm.
+    Defined.
+
+    Definition FSet_rec_beta_nl : forall (x : FSet A),
+        ap FSet_rec (nl x) 
+        =
+        nlP (FSet_rec x).
+    Proof.
+      intros.
+      unfold FSet_rec.
+      eapply (cancelL (transport_const (nl x) _)).
+      simple refine ((apD_const _ _)^ @ _).
+      apply FSet_ind_beta_nl.
+    Defined.
+
+    Definition FSet_rec_beta_nr : forall (x : FSet A),
+        ap FSet_rec (nr x) 
+        =
+        nrP (FSet_rec x).
+    Proof.
+      intros.
+      unfold FSet_rec.
+      eapply (cancelL (transport_const (nr x) _)).
+      simple refine ((apD_const _ _)^ @ _).
+      apply FSet_ind_beta_nr.
+    Defined.
+
+    Definition FSet_rec_beta_idem : forall (a : A),
+        ap FSet_rec (idem a) 
+        =
+        idemP a.
+    Proof.
+      intros.
+      unfold FSet_rec.
+      eapply (cancelL (transport_const (idem a) _)).
+      simple refine ((apD_const _ _)^ @ _).
+      apply FSet_ind_beta_idem.
+    Defined.
+    
+  End FSet_recursion.
+
+  Instance FSet_recursion A : HitRecursion (FSet A) :=
+    {
+      indTy := _; recTy := _; 
+      H_inductor := FSet_ind A; H_recursor := FSet_rec A
+    }.
+
+End FSet.
+
+Section set_sphere.
+  From HoTT.HIT Require Import Circle.
+  Context `{Univalence}.
+  Instance S1_recursion : HitRecursion S1 :=
+    {
+      indTy := _; recTy := _; 
+      H_inductor := S1_ind; H_recursor := S1_rec
+    }.
+
+  Variable A : Type.
+
+  Definition f (x : S1) : x = x.
+  Proof.
+    hrecursion x.
+    - exact loop.
+    - refine (transport_paths_FlFr _ _ @ _). 
+      hott_simpl.
+  Defined.
+
+  Definition S1op (x y : S1) : S1.
+  Proof.
+    hrecursion y.
+    - exact x. (* x + base = x *)
+    - apply f. 
+  Defined.
+
+  Lemma S1op_nr (x : S1) : S1op x base = x.
+  Proof. reflexivity. Defined.
+
+  Lemma S1op_nl (x : S1) : S1op base x = x.
+  Proof.
+    hrecursion x.
+    - exact loop.
+    - refine (transport_paths_FlFr loop _ @ _).
+      hott_simpl.
+      apply moveR_pM. apply moveR_pM. hott_simpl.
+      refine (ap_V _ _ @ _).
+      f_ap. apply S1_rec_beta_loop.
+  Defined.
+
+  Lemma S1op_assoc (x y z : S1) : S1op x (S1op y z) = S1op (S1op x y) z.
+  Proof.
+    hrecursion z.
+    - reflexivity.
+    - refine (transport_paths_FlFr loop _ @ _).
+      hott_simpl.
+      apply moveR_Mp. hott_simpl.
+      rewrite S1_rec_beta_loop.
+      rewrite ap_compose.
+      rewrite S1_rec_beta_loop.
+      hrecursion y.
+      + symmetry. apply S1_rec_beta_loop.
+      + apply is1type_S1. 
+  Qed.
+
+  Lemma S1op_comm (x y : S1) : S1op x y = S1op y x.
+  Proof.
+    hrecursion x.
+    - apply S1op_nl.
+    - hrecursion y.
+      + rewrite transport_paths_FlFr. hott_simpl. 
+        rewrite S1_rec_beta_loop. reflexivity.
+      + apply is1type_S1.
+  Defined.
+
+  Definition FSet_to_S : FSet A -> S1.
+  Proof.
+    hrecursion.
+    - exact base.
+    - intro a. exact base.
+    - exact S1op.
+    - apply S1op_assoc.
+    - apply S1op_comm.
+    - apply S1op_nl.
+    - apply S1op_nr.
+    - simpl. reflexivity.
+  Defined.
+
+  Lemma FSet_S_ap : (nl (E A)) = (nr ∅) -> idpath = loop.
+  Proof.
+    intros H1.
+    enough (ap FSet_to_S (nl ∅) = ap FSet_to_S (nr ∅)) as H'.
+    - rewrite FSet_rec_beta_nl in H'. 
+      rewrite FSet_rec_beta_nr in H'.
+      simpl in H'. unfold S1op_nr in H'.
+      exact H'^.
+    - f_ap.
+  Defined.
+
+  Lemma FSet_not_hset : IsHSet (FSet A) -> False.
+  Proof.
+    intros H1.
+    enough (idpath = loop). 
+    - assert (S1_encode _ idpath = S1_encode _ (loopexp loop (pos Int.one))) as H' by f_ap.
+      rewrite S1_encode_loopexp in H'. simpl in H'. symmetry in H'.
+      apply (pos_neq_zero H').
+    - apply FSet_S_ap.
+      apply set_path2.
+  Qed.
+
+End set_sphere.

FiniteSets/misc/ordered.v

@@ -0,0 +1,274 @@
+(** If [A] has a total order, then we can pick the minimum of finite sets. *)
+Require Import HoTT HitTactics.
+Require Import kuratowski.kuratowski_sets kuratowski.operations kuratowski.properties.
+
+Definition relation A := A -> A -> Type.
+
+Section TotalOrder.
+  Class IsTop (A : Type) (R : relation A) (a : A) :=
+    top_max : forall x, R x a.
+  
+  Class LessThan (A : Type) :=
+    leq : relation A.
+  
+  Class Antisymmetric {A} (R : relation A) :=
+    antisymmetry : forall x y, R x y -> R y x -> x = y.
+  
+  Class Total {A} (R : relation A) :=
+    total : forall x y,  x = y \/ R x y \/ R y x. 
+  
+  Class TotalOrder (A : Type) {R : LessThan A} :=
+    { TotalOrder_Reflexive :> Reflexive R | 2 ;
+      TotalOrder_Antisymmetric :> Antisymmetric R | 2; 
+      TotalOrder_Transitive :> Transitive R | 2;
+      TotalOrder_Total :> Total R | 2; }.
+End TotalOrder.
+
+Section minimum.
+  Context {A : Type}.
+  Context `{TotalOrder A}.
+
+  Definition min (x y : A) : A.
+  Proof.
+    destruct (@total _ R _ x y).
+    - apply x.
+    - destruct s as [s | s].
+      * apply x.
+      * apply y.
+  Defined.
+
+  Lemma min_spec1 x y : R (min x y) x.
+  Proof.
+    unfold min.
+    destruct (total x y) ; simpl.
+    - reflexivity.
+    - destruct s as [ | t].
+      * reflexivity.
+      * apply t.
+  Defined.
+
+  Lemma min_spec2 x y z : R z x -> R z y -> R z (min x y).
+  Proof.
+    intros.
+    unfold min.
+    destruct (total x y) as [ | s].
+    * assumption.
+    * try (destruct s) ; assumption.
+  Defined.
+  
+  Lemma min_comm x y : min x y = min y x.
+  Proof.
+    unfold min.
+    destruct (total x y) ; destruct (total y x) ; simpl.
+    - assumption.
+    - destruct s as [s | s] ; auto.
+    - destruct s as [s | s] ; symmetry ; auto.
+    - destruct s as [s | s] ; destruct s0 as [s0 | s0] ; try reflexivity.
+      * apply (@antisymmetry _ R _ _) ; assumption.
+      * apply (@antisymmetry _ R _ _) ; assumption.
+  Defined.
+
+  Lemma min_idem x : min x x = x.
+  Proof.
+    unfold min.
+    destruct (total x x) ; simpl.
+    - reflexivity.
+    - destruct s ; reflexivity.
+  Defined.
+
+  Lemma min_assoc x y z : min (min x y) z = min x (min y z).
+  Proof.
+    apply (@antisymmetry _ R _ _).
+    - apply min_spec2.
+      * etransitivity ; apply min_spec1.
+      * apply min_spec2.
+        ** etransitivity ; try (apply min_spec1).
+           simpl.
+           rewrite min_comm ; apply min_spec1.
+        ** rewrite min_comm ; apply min_spec1.
+    - apply min_spec2.
+      * apply min_spec2.
+        ** apply min_spec1.
+        ** etransitivity.
+           { rewrite min_comm ; apply min_spec1. }
+           apply min_spec1.
+      * transitivity (min y z); simpl
+        ; rewrite min_comm ; apply min_spec1.
+  Defined.
+  
+  Variable (top : A).
+  Context `{IsTop A R top}.
+
+  Lemma min_nr x : min x top = x.
+  Proof.
+    intros.
+    unfold min.
+    destruct (total x top).
+    - reflexivity.
+    - destruct s.
+      * reflexivity.
+      * apply (@antisymmetry _ R _ _).
+        ** assumption.
+        ** refine (top_max _). apply _.
+  Defined.
+
+  Lemma min_nl x : min top x = x.
+  Proof.
+    rewrite min_comm.
+    apply min_nr.
+  Defined.
+
+  Lemma min_top_l x y : min x y = top -> x = top.
+  Proof.
+    unfold min.
+    destruct (total x y).
+    - apply idmap.
+    - destruct s as [s | s].
+      * apply idmap.
+      * intros X.
+        rewrite X in s.
+        apply (@antisymmetry _ R _ _).
+        ** apply top_max.
+        ** assumption.
+  Defined.
+  
+  Lemma min_top_r x y : min x y = top -> y = top.
+  Proof.
+    rewrite min_comm.
+    apply min_top_l.
+  Defined.
+
+End minimum.
+
+Section add_top.
+  Variable (A : Type).
+  Context `{TotalOrder A}.
+
+  Definition Top := A + Unit.
+  Definition top : Top := inr tt.
+
+  Global Instance RTop : LessThan Top.
+  Proof.
+    unfold relation.
+    induction 1 as [a1 | ] ; induction 1 as [a2 | ].
+    - apply (R a1 a2).
+    - apply Unit_hp.
+    - apply False_hp.
+    - apply Unit_hp.
+  Defined.
+
+  Global Instance rtop_hprop :
+    is_mere_relation A R -> is_mere_relation Top RTop.
+  Proof.
+    intros P a b.
+    destruct a ; destruct b ; apply _.
+  Defined.
+  
+  Global Instance RTopOrder : TotalOrder Top.
+  Proof.
+    split.
+    - intros x ; induction x ; unfold RTop ; simpl.
+      * reflexivity.
+      * apply tt.
+    - intros x y ; induction x as [a1 | ] ; induction y as [a2 | ] ; unfold RTop ; simpl
+      ; try contradiction.
+      * intros ; f_ap.
+        apply (@antisymmetry _ R _ _) ; assumption.
+      * intros ; induction b ; induction b0.
+        reflexivity.
+    - intros x y z ; induction x as [a1 | b1] ; induction y as [a2 | b2]
+      ; induction z as [a3 | b3] ; unfold RTop ; simpl
+      ; try contradiction ; intros ; try (apply tt).
+      transitivity a2 ; assumption.
+    - intros x y.
+      unfold RTop ; simpl.
+      induction x as [a1 | b1] ; induction y as [a2 | b2] ; try (apply (inl idpath)).
+      * destruct (TotalOrder_Total a1 a2).
+        ** left ; f_ap ; assumption.
+        ** right ; assumption.
+      * apply (inr(inl tt)).
+      * apply (inr(inr tt)).
+      * left ; induction b1 ; induction b2 ; reflexivity.
+  Defined.
+
+  Global Instance top_a_top : IsTop Top RTop top.
+  Proof.
+    intro x ; destruct x ; apply tt.
+  Defined.
+End add_top.  
+
+(** If [A] has a total order, then a nonempty finite set has a minimum element. *)
+Section min_set.
+  Variable (A : Type).
+  Context `{TotalOrder A}.
+  Context `{is_mere_relation A R}.
+  Context `{Univalence} `{IsHSet A}.
+
+  Definition min_set : FSet A -> Top A.
+  Proof.
+    hrecursion.
+    - apply (top A).
+    - apply inl.
+    - apply min.
+    - intros ; symmetry ; apply min_assoc.
+    - apply min_comm.
+    - apply min_nl. apply _.
+    - apply min_nr. apply _.
+    - intros ; apply min_idem.
+  Defined.
+
+  Definition empty_min : forall (X : FSet A), min_set X = top A -> X = ∅.
+  Proof.
+    simple refine (FSet_ind _ _ _ _ _ _ _ _ _ _ _)
+    ; try (intros ; apply path_forall ; intro q ; apply set_path2)
+    ; simpl.
+    - intros ; reflexivity.
+    - intros.
+      unfold top in X.
+      enough Empty.
+      { contradiction. }
+      refine (not_is_inl_and_inr' (inl a) _ _).
+      * apply tt.
+      * rewrite X ; apply tt.
+    - intros.
+      assert (min_set x = top A).
+      {
+        simple refine (min_top_l _ _ (min_set y) _) ; assumption.
+      }
+      rewrite (X X2).
+      rewrite nl.
+      assert (min_set y = top A).
+      { simple refine (min_top_r _ (min_set x) _ _) ; assumption. }
+      rewrite (X0 X3).
+      reflexivity.
+  Defined.
+  
+  Definition min_set_spec (a : A) : forall (X : FSet A),
+      a ∈ X -> RTop A (min_set X) (inl a).
+  Proof.
+    simple refine (FSet_ind _ _ _ _ _ _ _ _ _ _ _)
+    ; try (intros ; apply path_ishprop)
+    ; simpl.    
+    - contradiction.
+    - intros.
+      strip_truncations.
+      rewrite X.
+      reflexivity.
+    - intros.
+      strip_truncations.
+      unfold member in X, X0.
+      destruct X1.
+      * specialize (X t).
+        assert (RTop A (min (min_set x) (min_set y)) (min_set x)) as X1.
+        { apply min_spec1. }
+        etransitivity.
+        { apply X1. }
+        assumption.
+      * specialize (X0 t).
+        assert (RTop A (min (min_set x) (min_set y)) (min_set y)) as X1.
+        { rewrite min_comm ; apply min_spec1. }
+        etransitivity.
+        { apply X1. }
+        assumption.
+  Defined.
+End min_set.

FiniteSets/misc/projective.v

@@ -1,7 +1,6 @@
 Require Import HoTT HitTactics.
-Require Import variations.k_finite variations.b_finite.
+Require Import subobjects.k_finite subobjects.b_finite FSets.
-Require Import FSets.
+Require Import misc.T.
-Require Import representations.T.
 
 Class IsProjective (X : Type) :=
   projective : forall {P Q : Type} (p : P -> Q) (f : X -> Q),

FiniteSets/ordered.v

@@ -1,826 +0,0 @@
-Require Import HoTT.
-Require Import HitTactics.
-Require Import definition.
-Require Import operations.
-Require Import properties.
-
-Definition relation A := A -> A -> Type.
-
-Section TotalOrder.
-  Class IsTop (A : Type) (R : relation A) (a : A) :=
-    top_max : forall x, R x a.
-  
-  Class LessThan (A : Type) :=
-    leq : relation A.
-  
-  Class Antisymmetric {A} (R : relation A) :=
-    antisymmetry : forall x y, R x y -> R y x -> x = y.
-  
-  Class Total {A} (R : relation A) :=
-    total : forall x y,  x = y \/ R x y \/ R y x. 
-  
-  Class TotalOrder (A : Type) {R : LessThan A} :=
-    { TotalOrder_Reflexive :> Reflexive R | 2 ;
-      TotalOrder_Antisymmetric :> Antisymmetric R | 2; 
-      TotalOrder_Transitive :> Transitive R | 2;
-      TotalOrder_Total :> Total R | 2; }.
-End TotalOrder.
-
-Section minimum.
-  Context {A : Type}.
-  Context `{TotalOrder A}.
-
-  Definition min (x y : A) : A.
-  Proof.
-    destruct (@total _ R _ x y).
-    - apply x.
-    - destruct s as [s | s].
-      * apply x.
-      * apply y.
-  Defined.
-
-  Lemma min_spec1 x y : R (min x y) x.
-  Proof.
-    unfold min.
-    destruct (total x y) ; simpl.
-    - reflexivity.
-    - destruct s as [ | t].
-      * reflexivity.
-      * apply t.
-  Defined.
-
-  Lemma min_spec2 x y z : R z x -> R z y -> R z (min x y).
-  Proof.
-    intros.
-    unfold min.
-    destruct (total x y) as [ | s].
-    * assumption.
-    * try (destruct s) ; assumption.
-  Defined.
-  
-  Lemma min_comm x y : min x y = min y x.
-  Proof.
-    unfold min.
-    destruct (total x y) ; destruct (total y x) ; simpl.
-    - assumption.
-    - destruct s as [s | s] ; auto.
-    - destruct s as [s | s] ; symmetry ; auto.
-    - destruct s as [s | s] ; destruct s0 as [s0 | s0] ; try reflexivity.
-      * apply (@antisymmetry _ R _ _) ; assumption.
-      * apply (@antisymmetry _ R _ _) ; assumption.
-  Defined.
-
-  Lemma min_idem x : min x x = x.
-  Proof.
-    unfold min.
-    destruct (total x x) ; simpl.
-    - reflexivity.
-    - destruct s ; reflexivity.
-  Defined.
-
-  Lemma min_assoc x y z : min (min x y) z = min x (min y z).
-  Proof.
-    apply (@antisymmetry _ R _ _).
-    - apply min_spec2.
-      * etransitivity ; apply min_spec1.
-      * apply min_spec2.
-        ** etransitivity ; try (apply min_spec1).
-           simpl.
-           rewrite min_comm ; apply min_spec1.
-        ** rewrite min_comm ; apply min_spec1.
-    - apply min_spec2.
-      * apply min_spec2.
-        ** apply min_spec1.
-        ** etransitivity.
-           { rewrite min_comm ; apply min_spec1. }
-           apply min_spec1.
-      * transitivity (min y z); simpl
-        ; rewrite min_comm ; apply min_spec1.
-  Defined.
-  
-  Variable (top : A).
-  Context `{IsTop A R top}.
-
-  Lemma min_nr x : min x top = x.
-  Proof.
-    intros.
-    unfold min.
-    destruct (total x top).
-    - reflexivity.
-    - destruct s.
-      * reflexivity.
-      * apply (@antisymmetry _ R _ _).
-        ** assumption.
-        ** refine (top_max _). apply _.
-  Defined.
-
-  Lemma min_nl x : min top x = x.
-  Proof.
-    rewrite min_comm.
-    apply min_nr.
-  Defined.
-
-  Lemma min_top_l x y : min x y = top -> x = top.
-  Proof.
-    unfold min.
-    destruct (total x y).
-    - apply idmap.
-    - destruct s as [s | s].
-      * apply idmap.
-      * intros X.
-        rewrite X in s.
-        apply (@antisymmetry _ R _ _).
-        ** apply top_max.
-        ** assumption.
-  Defined.
-  
-  Lemma min_top_r x y : min x y = top -> y = top.
-  Proof.
-    rewrite min_comm.
-    apply min_top_l.
-  Defined.
-
-End minimum.
-
-Section add_top.
-  Variable (A : Type).
-  Context `{TotalOrder A}.
-
-  Definition Top := A + Unit.
-  Definition top : Top := inr tt.
-
-  Global Instance RTop : LessThan Top.
-  Proof.
-    unfold relation.
-    induction 1 as [a1 | ] ; induction 1 as [a2 | ].
-    - apply (R a1 a2).
-    - apply Unit_hp.
-    - apply False_hp.
-    - apply Unit_hp.
-  Defined.
-
-  Global Instance rtop_hprop :
-    is_mere_relation A R -> is_mere_relation Top RTop.
-  Proof.
-    intros P a b.
-    destruct a ; destruct b ; apply _.
-  Defined.
-  
-  Global Instance RTopOrder : TotalOrder Top.
-  Proof.
-    split.
-    - intros x ; induction x ; unfold RTop ; simpl.
-      * reflexivity.
-      * apply tt.
-    - intros x y ; induction x as [a1 | ] ; induction y as [a2 | ] ; unfold RTop ; simpl
-      ; try contradiction.
-      * intros ; f_ap.
-        apply (@antisymmetry _ R _ _) ; assumption.
-      * intros ; induction b ; induction b0.
-        reflexivity.
-    - intros x y z ; induction x as [a1 | b1] ; induction y as [a2 | b2]
-      ; induction z as [a3 | b3] ; unfold RTop ; simpl
-      ; try contradiction ; intros ; try (apply tt).
-      transitivity a2 ; assumption.
-    - intros x y.
-      unfold RTop ; simpl.
-      induction x as [a1 | b1] ; induction y as [a2 | b2] ; try (apply (inl idpath)).
-      * destruct (TotalOrder_Total a1 a2).
-        ** left ; f_ap ; assumption.
-        ** right ; assumption.
-      * apply (inr(inl tt)).
-      * apply (inr(inr tt)).
-      * left ; induction b1 ; induction b2 ; reflexivity.
-  Defined.
-
-  Global Instance top_a_top : IsTop Top RTop top.
-  Proof.
-    intro x ; destruct x ; apply tt.
-  Defined.
-End add_top.  
-
-Section min_set.
-  Variable (A : Type).
-  Context `{TotalOrder A}.
-  Context `{is_mere_relation A R}.
-  Context `{Univalence} `{IsHSet A}.
-
-  Definition min_set : FSet A -> Top A.
-  Proof.
-    hrecursion.
-    - apply (top A).
-    - apply inl.
-    - apply min.
-    - intros ; symmetry ; apply min_assoc.
-    - apply min_comm.
-    - apply min_nl. apply _.
-    - apply min_nr. apply _.
-    - intros ; apply min_idem.
-  Defined.
-
-  Definition empty_min : forall (X : FSet A), min_set X = top A -> X = ∅.
-  Proof.
-    simple refine (FSet_ind _ _ _ _ _ _ _ _ _ _ _)
-    ; try (intros ; apply path_forall ; intro q ; apply set_path2)
-    ; simpl.
-    - intros ; reflexivity.
-    - intros.
-      unfold top in X.
-      enough Empty.
-      { contradiction. }
-      refine (not_is_inl_and_inr' (inl a) _ _).
-      * apply tt.
-      * rewrite X ; apply tt.
-    - intros.
-      assert (min_set x = top A).
-      {
-        simple refine (min_top_l _ _ (min_set y) _) ; assumption.
-      }
-      rewrite (X X2).
-      rewrite nl.
-      assert (min_set y = top A).
-      { simple refine (min_top_r _ (min_set x) _ _) ; assumption. }
-      rewrite (X0 X3).
-      reflexivity.
-  Defined.
-  
-  Definition min_set_spec (a : A) : forall (X : FSet A),
-      a ∈ X -> RTop A (min_set X) (inl a).
-  Proof.
-    simple refine (FSet_ind _ _ _ _ _ _ _ _ _ _ _)
-    ; try (intros ; apply path_ishprop)
-    ; simpl.    
-    - contradiction.
-    - intros.
-      strip_truncations.
-      rewrite X.
-      reflexivity.
-    - intros.
-      strip_truncations.
-      unfold member in X, X0.
-      destruct X1.
-      * specialize (X t).
-        assert (RTop A (min (min_set x) (min_set y)) (min_set x)) as X1.
-        { apply min_spec1. }
-        etransitivity.
-        { apply X1. }
-        assumption.
-      * specialize (X0 t).
-        assert (RTop A (min (min_set x) (min_set y)) (min_set y)) as X1.
-        { rewrite min_comm ; apply min_spec1. }
-        etransitivity.
-        { apply X1. }
-        assumption.
-  Defined.
-
-End min_set.
-
-
-(*
-Ltac eq_neq_tac :=
-match goal  with
-    |  [ H: ?x <> E, H': ?x = E |- _ ] => destruct H; assumption
-end.
-
-
-Ltac destruct_match_1 :=
-	repeat match goal with
-    | [|- match ?X with | _ => _ end ] => destruct X
-    | [|- ?X = ?Y ] => apply path_ishprop
-    | [ H: ?x <> E  |- Empty ] => destruct H
-    | [  H1: ?x = E, H2: ?y = E, H3: ?w ∪ ?q  = E |- ?r = E]
-    			=> rewrite H1, H2 in H3; rewrite nl in H3;  rewrite nl in H3
-  end.
-			
-
-Lemma transport_dom_eq (D1 D2 C: Type) (P: D1 = D2) (f: D1 -> C) : 
-transport (fun T: Type => T -> C) P f = fun y => f (transport (fun X => X) P^ y).
-Proof.
-induction P.
-hott_simpl.
-Defined.
-
-Lemma transport_dom_eq_gen (Ty: Type) (D1 D2: Ty) (C: Type) (P: D1 = D2) 
-			(Q : Ty -> Type) (f: Q D1 -> C) : 
-transport (fun X: Ty => Q X -> C) P f = fun y => f (transport Q P^ y).
-Proof.
-induction P.
-hott_simpl.
-Defined.
-			
-(* Lemma min {HFun: Funext} (x: FSet A): x <> ∅  -> A. *)
-(* Proof. *)
-(* hrecursion x.  *)
-(* - intro H. destruct H. reflexivity. *)
-(* - intros. exact a. *)
-(* - intros x y rx ry H. *)
-(* 	apply union_non_empty' in H. *)
-(* 	destruct H.  *)
-(* 	+ destruct p. specialize (rx fst). exact rx. *)
-(* 	+ destruct s.  *)
-(* 		* destruct p. specialize (ry snd). exact ry. *)
-(* 		* destruct p.  specialize (rx fst). specialize (ry snd). *)
-(* 			destruct (TotalOrder_Total rx ry) as [Heq | [ Hx | Hy ]]. *)
-(* 			** exact rx. *)
-(* 			** exact rx. *)
-(* 			** exact ry. *)
-(* - intros. rewrite transport_dom_eq_gen. *)
-(* 	apply path_forall. intro y0.  *)
-(* 	destruct (  union_non_empty' x y ∪ z  *)
-(* 	(transport (fun X : FSet A => X <> ∅) (assoc x y z)^ y0)) *)
-(* 	as [[ G1 G2] | [[ G3 G4] | [G5 G6]]]. *)
-(* 	+ pose (G2' := G2). apply  eset_union_lr in G2'; destruct G2'. cbn. *)
-(* 		destruct (union_non_empty' x ∪ y z y0) as  *)
-(* 	 [[H'x H'y] | [ [H'a H'b] | [H'c H'd]]]; try eq_neq_tac. *)
-(* 	 destruct (union_non_empty' x y H'x).  *)
-(* 	 	** destruct p. assert (G1 = fst0).  apply path_forall. intro. *)
-(* 		 apply path_ishprop. rewrite X. reflexivity.  *)
-(* 	 	** destruct s; destruct p; eq_neq_tac.  *)
-(* 	+ destruct (union_non_empty' y z G4)  as  *)
-(* 	[[H'x H'y] | [ [H'a H'b] | [H'c H'd]]]; try eq_neq_tac. *)
-(* 	destruct (union_non_empty' x ∪ y z y0). *)
-(* 		** destruct p. cbn. destruct (union_non_empty' x y fst). *)
-(* 			*** destruct p; eq_neq_tac. *)
-(* 			*** destruct s. destruct p. *)
-(* 				**** assert (H'x = snd0).  apply path_forall. intro. *)
-(* 		 apply path_ishprop. rewrite X. reflexivity. *)
-(* 		 	  **** destruct p. eq_neq_tac. *)
-(* 		** destruct s; destruct p; try eq_neq_tac. *)
-(* 		** destruct (union_non_empty' x ∪ y z y0). *)
-(* 			*** destruct p. eq_neq_tac. *)
-(* 			*** destruct s. destruct p. *)
-(* 				**** assert (H'b = snd).  apply path_forall. intro. *)
-(* 		 			apply path_ishprop. rewrite X. reflexivity. *)
-(* 		 		**** destruct p. assert (x ∪ y = E). *)
-(* 		 		rewrite H'a, G3. apply union_idem.  eq_neq_tac.  *)
-(* 		** cbn. destruct (TotalOrder_Total (py H'c) (pz H'd)). *)
-(* 			*** destruct (union_non_empty' x ∪ y z y0). *)
-(* 				**** destruct p0. eq_neq_tac. *)
-(* 				**** destruct s. *)
-(* 					*****  destruct p0. rewrite G3, nl in fst. eq_neq_tac. *)
-(* 					*****  destruct p0. destruct (union_non_empty' x y fst). *)
-(* 						****** destruct p0. eq_neq_tac. *)
-(* 						****** destruct s.  *)
-(* 						 ******* destruct p0.  *)
-(* 						 				destruct (TotalOrder_Total (py snd0) (pz snd)). *)
-(* 						 				f_ap. apply path_forall. intro. *)
-(* 		 								apply path_ishprop.  *)
-(* 		 								destruct s. f_ap. apply path_forall. intro. *)
-(* 		 								apply path_ishprop. *)
-(* 		 								rewrite p. f_ap. apply path_forall. intro. *)
-(* 		 								apply path_ishprop.  *)
-(* 		 				******* destruct p0. eq_neq_tac. *)
-(* 		 	*** destruct (union_non_empty' x ∪ y z y0). *)
-(* 		 		**** destruct p. eq_neq_tac. *)
-(* 		 		**** destruct s0. destruct p. rewrite comm in fst. *)
-(* 		 				 apply eset_union_l in fst. eq_neq_tac. *)
-(* 		 				 destruct p.  *)
-(* 		 				 destruct (union_non_empty' x y fst). *)
-(* 		 				 ***** destruct p; eq_neq_tac. *)
-(* 		 				 ***** destruct s0. destruct p.  *)
-(* 		 				 		destruct (TotalOrder_Total (py snd0) (pz snd)); *)
-(* 		 				 		destruct s; try (f_ap;  apply path_forall; intro; *)
-(* 		 														 apply path_ishprop). *)
-(* 		 						rewrite p. f_ap;  apply path_forall; intro; *)
-(* 		 														 apply path_ishprop. *)
-(* 		 						destruct s0. 		f_ap;  apply path_forall; intro; *)
-(* 		 														 apply path_ishprop. *)
-(* 		 						assert (snd0 = H'c).   apply path_forall; intro; *)
-(* 		 														 apply path_ishprop. *)
-(* 		 						assert (snd = H'd).   apply path_forall; intro; *)
-(* 		 														 apply path_ishprop. *)
-(* 		 						rewrite <- X0 in r. rewrite X in r0. *)
-(* 		 						apply TotalOrder_Antisymmetric; assumption. *)
-(* 		 						destruct s0.				 *)
-(* 		 						assert (snd0 = H'c).   apply path_forall; intro; *)
-(* 		 														 apply path_ishprop. *)
-(* 		 						assert (snd = H'd).   apply path_forall; intro; *)
-(* 		 														 apply path_ishprop. *)
-(* 		 						rewrite <- X in r. rewrite X0 in r0. *)
-(* 		 						apply TotalOrder_Antisymmetric; assumption. *)
-(* 		 						f_ap;  apply path_forall; intro; *)
-(* 		 														 apply path_ishprop. *)
-(* 		 						destruct p; eq_neq_tac. *)
-(* 	+ cbn. destruct (union_non_empty' y z G6). *)
-(* 		** destruct p. destruct ( union_non_empty' x ∪ y z y0). *)
-(* 			*** destruct p. destruct (union_non_empty' x y fst0). *)
-(* 				**** destruct p; eq_neq_tac. *)
-(* 				**** destruct s; destruct p. eq_neq_tac.		 *)
-(* 						assert (fst1 = G5).   apply path_forall; intro; *)
-(* 		 														 apply path_ishprop. *)
-(* 		 				assert (fst = snd1).   apply path_forall; intro; *)
-(* 		 														 apply path_ishprop. *)
-(* 		 				rewrite X, X0.			 *)
-(* 		 			  destruct (TotalOrder_Total (px G5) (py snd1)). *)
-(* 		 			  reflexivity. *)
-(* 		 			  destruct s; reflexivity. *)
-(* 		 	*** destruct s; destruct p; eq_neq_tac.  *)
-(* 		** destruct (union_non_empty' x ∪ y z y0).  *)
-(* 			*** destruct p. destruct s; destruct p; eq_neq_tac. *)
-(* 			*** destruct s. destruct p. destruct s0. destruct p. *)
-(* 					apply eset_union_l in fst0. eq_neq_tac. *)
-(* 				**** destruct p. 		 *)
-(* 		 					assert (snd = snd0).   apply path_forall; intro; *)
-(* 		 														 apply path_ishprop.		  *)
-				
-(* 				destruct (union_non_empty' x y fst0).  *)
-(* 				destruct p. *)
-(* 				 assert (fst1 = G5).  apply path_forall; intro; *)
-(* 		 														 apply path_ishprop.  *)
-(* 		 				assert (fst = snd1).  apply set_path2. *)
-(* 					***** rewrite X0. rewrite <- X. reflexivity. *)
-(* 					*****  destruct s; destruct p; eq_neq_tac. *)
-(* 				**** destruct s0. destruct p0. destruct p.  *)
-(* 					***** apply eset_union_l in fst. eq_neq_tac. *)
-(* 					***** destruct p, p0. *)
-(* 					assert (snd0 = snd).   apply path_forall; intro; *)
-(* 		 														 apply path_ishprop. *)
-(* 		 			rewrite X.												 *)
-(* 					 destruct (union_non_empty' x y fst0). *)
-(* 					 destruct p; eq_neq_tac. *)
-(* 					 destruct s. destruct p; eq_neq_tac. *)
-(* 					 destruct p. *)
-(* 					 assert (fst = snd1).   apply path_forall; intro; *)
-(* 		 														 apply path_ishprop. *)
-(* 						assert (fst1 = G5).   apply path_forall; intro; *)
-(* 		 														 apply path_ishprop.								  *)
-(* 						rewrite <- X0. rewrite X1. 											 *)
-(* 					  destruct (TotalOrder_Total (py fst) (pz snd)). *)
-(* 					  ****** rewrite <- p.  *)
-(* 					   destruct (TotalOrder_Total (px G5) (py fst)). *)
-(* 					   rewrite <- p0.  *)
-(* 					 		destruct (TotalOrder_Total (px G5) (px G5)). *)
-(* 					 		reflexivity. *)
-(* 					 		destruct s; reflexivity. *)
-(* 					 		destruct s. destruct (TotalOrder_Total (px G5) (py fst)). *)
-(* 					 		reflexivity. *)
-(* 					 		destruct s. *)
-(* 					 		reflexivity. *)
-(* 					 		apply TotalOrder_Antisymmetric; assumption. *)
-(* 					 		destruct (TotalOrder_Total (py fst) (py fst)). *)
-(* 					 		reflexivity. *)
-(* 					 		destruct s; *)
-(* 					 		reflexivity. *)
-(* 					 ****** destruct s.  *)
-(* 					 	destruct (TotalOrder_Total (px G5) (py fst)). *)
-(* 					 	destruct (TotalOrder_Total (px G5) (pz snd)). *)
-(* 					 	reflexivity. *)
-(* 					 	destruct s. *)
-(* 					 	reflexivity. rewrite <- p in r.  *)
-(* 					 	apply TotalOrder_Antisymmetric; assumption. *)
-(* 					 	destruct s.  *)
-(* 					 	destruct ( TotalOrder_Total (px G5) (pz snd)). *)
-(* 					 	reflexivity. *)
-(* 					 	destruct s. reflexivity. *)
-(* 					 	apply (TotalOrder_Transitive (px G5)) in r.  *)
-(* 					 	apply TotalOrder_Antisymmetric; assumption. *)
-(* 					 	assumption. *)
-(* 					 	destruct (TotalOrder_Total (py fst) (pz snd)). reflexivity. *)
-(* 					 	destruct s. reflexivity. *)
-(* 					 	apply TotalOrder_Antisymmetric; assumption. *)
-(* 					 ******* *)
-(* 					 	 	destruct ( TotalOrder_Total (px G5) (py fst)). *)
-(* 					 	 	reflexivity. *)
-(* 					 	 	destruct s. destruct (TotalOrder_Total (px G5) (pz snd)). *)
-(* 					 	 	reflexivity. destruct s; reflexivity. *)
-(* 					 	 	destruct ( TotalOrder_Total (px G5) (pz snd)). *)
-(* 					 	 	rewrite <- p. *)
-(* 					 	 	destruct (TotalOrder_Total (py fst) (px G5)). *)
-(* 					 	 	apply symmetry; assumption. *)
-(* 					 	 	destruct s. rewrite <- p in r. *)
-(* 					 	 	apply TotalOrder_Antisymmetric; assumption. *)
-(* 					 	 	reflexivity. destruct s.  *)
-(* 					 	 	assert ((py fst) = (pz snd)). apply TotalOrder_Antisymmetric. *)
-(* 					 	 	apply (TotalOrder_Transitive (py fst) (px G5)); assumption. *)
-(* 					 	 	assumption. rewrite X2. assert (px G5 = pz snd). *)
-(* 					 	 	 apply TotalOrder_Antisymmetric. assumption. *)
-(* 					 	 	 apply (TotalOrder_Transitive (pz snd) (py fst)); assumption. *)
-(* 					 	 	 rewrite X3. *)
-(* 					 	 	destruct ( TotalOrder_Total (pz snd) (pz snd)). *)
-(* 					 	 	reflexivity. destruct s; reflexivity. *)
-(* 					 	 	destruct (TotalOrder_Total (py fst) (pz snd)). *)
-(* 					 	 		 apply TotalOrder_Antisymmetric.  assumption. rewrite p. *)
-(* 					 	 	 apply (TotalOrder_Reflexive).  destruct s.  *)
-(* 					 	 		 apply TotalOrder_Antisymmetric;  assumption. reflexivity. *)
-(* - intros. rewrite transport_dom_eq_gen. *)
-(*   apply path_forall. intro y0. cbn. *)
-(*    destruct  *)
-(*   		(union_non_empty' x y  *)
-(*   		(transport (fun X : FSet A => X <> ∅) (comm x y)^ y0)) as  *)
-(*   		[[Hx Hy] | [ [Ha Hb] | [Hc Hd]]]; *)
-(*   	destruct (union_non_empty' y x y0) as  *)
-(*   	   [[H'x H'y] | [ [H'a H'b] | [H'c H'd]]]; *)
-(*   	   try (eq_neq_tac).  *)
-(*      assert (Hx = H'b).  apply path_forall. intro. *)
-(* 		 apply path_ishprop. rewrite X. reflexivity. *)
-(* 		 assert (Hb = H'x).  apply path_forall. intro. *)
-(* 		 apply path_ishprop. rewrite X. reflexivity. *)
-(* 		  assert (Hd = H'c).  apply path_forall. intro. *)
-(* 		 apply path_ishprop. rewrite X. *)
-(* 		  assert (H'd = Hc).  apply path_forall. intro. *)
-(* 		 apply path_ishprop. *)
-(* 		 rewrite X0. rewrite <- X. *)
-(* 	destruct  *)
-(* 		(TotalOrder_Total (px Hc) (py Hd)) as [G1 | [G2 | G3]]; *)
-(* 	destruct  *)
-(* 	(TotalOrder_Total (py Hd) (px Hc)) as [T1 | [T2 | T3]]; *)
-(* 	try (assumption); *)
-(* 	try (reflexivity); *)
-(* 	try (apply symmetry; assumption); *)
-(* 	try (apply TotalOrder_Antisymmetric; assumption). *)
-		 		  
-(* - intros. rewrite transport_dom_eq_gen. *)
-(*   apply path_forall. intro y. *)
-(*   destruct (union_non_empty' ∅ x (transport (fun X : FSet A => X <> ∅) (nl x)^ y)). *)
-(*   destruct p. eq_neq_tac.  *)
-(*   destruct s.  *)
-(*   destruct p. *)
-(*   assert (y = snd). *)
-(*     apply path_forall. intro. *)
-(*     apply path_ishprop. rewrite X. reflexivity. *)
-(*   destruct p. destruct fst. *)
-(* - intros. rewrite transport_dom_eq_gen. *)
-(*   apply path_forall. intro y. *)
-(*   destruct (union_non_empty' x ∅ (transport (fun X : FSet A => X <> ∅) (nr x)^ y)). *)
-(*   destruct p. assert (y = fst).  apply path_forall. intro. *)
-(* apply path_ishprop. rewrite X. reflexivity. *)
-(*   destruct s.  *)
-(*   destruct p.  *)
-(*   eq_neq_tac. *)
-(*   destruct p. *)
-(*   destruct snd. *)
-(* - intros. rewrite transport_dom_eq_gen. *)
-(* 	apply path_forall. intro y.  *)
-(*   destruct ( union_non_empty' {|x|} {|x|} (transport (fun X : FSet A => X <> ∅) (idem x)^ y)). *)
-(*   reflexivity. *)
-(*   destruct s. *)
-(*   reflexivity. *)
-(*   destruct p. *)
-(*   cbn. destruct  (TotalOrder_Total x x). reflexivity. *)
-(*   destruct s; reflexivity. *)
-(* Defined. *)
-	
-
-Definition minfset {HFun: Funext} : 
-	FSet A -> { Y: (FSet A) & (Y = E) + { a: A & Y = L a } }.
-intro X.
-hinduction X.
--  exists E. left. reflexivity.
-- intro a.  exists (L a). right. exists a. reflexivity.
-- intros IH1 IH2.
-  destruct IH1 as [R1 HR1].
-  destruct IH2 as [R2 HR2]. 
-  destruct HR1. 
-  destruct HR2.
-  exists E; left. reflexivity.
-  destruct s as [a Ha]. exists (L a). right.
-  exists a. reflexivity.
-  destruct HR2. 
-  destruct s as [a Ha].
-  exists (L a). right. exists a. reflexivity.
-  destruct s as [a1 Ha1].
-  destruct s0 as [a2 Ha2].
-  assert (a1 = a2 \/ R a1 a2 \/ R a2 a1).
-	apply TotalOrder_Total. 
-	destruct X.
-	exists (L a1). right. exists a1. reflexivity.
-	destruct s.
-	exists (L a1). right. exists a1. reflexivity.
-  exists (L a2). right. exists a2. reflexivity.
-  - cbn. intros R1 R2 R3.
-  destruct R1 as [Res1 HR1].
-  destruct HR1 as [HR1E | HR1S].
-  destruct R2 as [Res2 HR2].
-  destruct HR2 as [HR2E | HR2S].
-  destruct R3 as [Res3 HR3].
-  destruct HR3 as [HR3E | HR3S].
-  + cbn. reflexivity.
- 	+ cbn. reflexivity.
- 	+ cbn.   destruct R3 as [Res3 HR3].
-  destruct HR3 as [HR3E | HR3S].
-  * cbn. reflexivity.
-  * destruct HR2S as [a2 Ha2].  
-    destruct HR3S as [a3 Ha3].
-  	  destruct (TotalOrder_Total a2 a3).
-  	  ** cbn. reflexivity.
-  	  ** destruct s. cbn. reflexivity.
-  	  	   cbn. reflexivity.  	
-  	+  destruct HR1S as [a1 Ha1].
-  	 destruct R2 as [Res2 HR2].
-  destruct HR2 as [HR2E | HR2S].
-  destruct R3 as [Res3 HR3].
-  destruct HR3 as [HR3E | HR3S].
-  * cbn. reflexivity.
-  * destruct HR3S as [a3 Ha3].
-    destruct (TotalOrder_Total a1 a3). 
-    reflexivity.
-    destruct s; reflexivity.
-   * destruct HR2S as [a2 Ha2]. 
-  destruct R3 as [Res3 HR3].
-  destruct HR3 as [HR3E | HR3S].
-    cbn. destruct (TotalOrder_Total a1 a2).
-    cbn. reflexivity.
-    destruct s.
-    cbn. reflexivity.
-    cbn. reflexivity.
-    destruct HR3S as [a3 Ha3]. 
-     destruct (TotalOrder_Total a2 a3).
-     ** rewrite p. 
-     destruct (TotalOrder_Total a1 a3).
-     rewrite p0. 
-     destruct ( TotalOrder_Total a3 a3).
-     reflexivity.
-     destruct s; reflexivity.
-     destruct s. cbn.
-     destruct (TotalOrder_Total a1 a3).
-     reflexivity.
-     destruct s. reflexivity.
-     	assert (a1 = a3).
-	  apply TotalOrder_Antisymmetric; assumption. 
-	  rewrite X. reflexivity.
-	  cbn. destruct (TotalOrder_Total a3 a3).
-	  reflexivity.
-	  destruct s; reflexivity.
-    ** destruct s.
-    		 *** cbn. destruct (TotalOrder_Total a1 a2).
-    		 cbn. destruct (TotalOrder_Total a1 a3).
-    		  reflexivity.
-    		  destruct s. reflexivity.
-    		  rewrite <- p in r.
-    		    	assert (a1 = a3).
-	  apply TotalOrder_Antisymmetric; assumption. 
-	  rewrite X. reflexivity.
-	    destruct s. cbn.
-    	destruct (TotalOrder_Total a1 a3).
-    	reflexivity.
-    	destruct s. reflexivity.
-    	assert (R a1 a3).
-    apply (TotalOrder_Transitive a1 a2); assumption.
-    assert (a1 = a3).
-	  apply TotalOrder_Antisymmetric; assumption. 
-	  rewrite X0. reflexivity.
-    	cbn. destruct (TotalOrder_Total a2 a3).
-    	reflexivity.
-    	destruct s.
-    	reflexivity.
-    assert (a2 = a3).
-	  apply TotalOrder_Antisymmetric; assumption. 
-	  rewrite X. reflexivity.
-   *** cbn. destruct (TotalOrder_Total a1 a3).
-   rewrite p. destruct (TotalOrder_Total a3 a2).
-   cbn. destruct (TotalOrder_Total a3 a3).
-   reflexivity. destruct s; reflexivity.
-   destruct s. cbn.
-   destruct (TotalOrder_Total a3 a3).
-   reflexivity. destruct s; reflexivity.
-   cbn. destruct (TotalOrder_Total a2 a3).
-   rewrite p0.
-   reflexivity.
-   destruct s. 
-    assert (a2 = a3).
-	  apply TotalOrder_Antisymmetric; assumption. 
-	  rewrite X. reflexivity. reflexivity.
-	  destruct s.
-	  cbn.
-    destruct (TotalOrder_Total a1 a2).
-    cbn. 
-  destruct (TotalOrder_Total a1 a3).
-  reflexivity.
-  assert (a1 = a3).
-  apply TotalOrder_Antisymmetric. assumption.
-  rewrite <- p in r. assumption.
-  destruct s. reflexivity. rewrite X. reflexivity.
-  destruct s. cbn. 
-  destruct (TotalOrder_Total a1 a3). reflexivity.
-  destruct s. reflexivity.
-  assert (a1 = a3).
-  apply TotalOrder_Antisymmetric; assumption.
-  rewrite X. reflexivity.
-  cbn.  destruct  (TotalOrder_Total a2 a3).
-  rewrite p in r1.
-  assert (a2 = a1).
-  transitivity a3.
-  assumption.
-  apply TotalOrder_Antisymmetric; assumption.
-  rewrite X. reflexivity.
-  destruct s. 
-   assert (a1 = a2).
-    apply TotalOrder_Antisymmetric.
-   apply (TotalOrder_Transitive a1 a3); assumption.
-   assumption.
-  rewrite X. reflexivity.
-   assert (a1 = a3).
-    apply TotalOrder_Antisymmetric.
-    assumption.
-   apply (TotalOrder_Transitive a3 a2); assumption.
-   rewrite X. reflexivity.
-  destruct ( TotalOrder_Total a1 a2).
-  cbn.
-  destruct (TotalOrder_Total a1 a3).
-  rewrite p0.
-  reflexivity.
-  destruct s. 
-  assert (a1 = a3).
-    apply TotalOrder_Antisymmetric; assumption. 
-    rewrite X. reflexivity. reflexivity. 
-  destruct s.
-  cbn.
-  destruct (TotalOrder_Total a1 a3 ).
-  rewrite p.
-  reflexivity.
-  destruct s. 
-    assert (a1 = a3).
-    apply TotalOrder_Antisymmetric; assumption. 
-    rewrite X. reflexivity. reflexivity. 
-  cbn.
-  destruct (TotalOrder_Total a1 a3 ).
-  assert (a2 = a3).
-  rewrite p in r1.
-  apply TotalOrder_Antisymmetric; assumption. 
-	  rewrite X. destruct (TotalOrder_Total a3 a3). reflexivity.
-	  destruct s; reflexivity.
-  destruct s. 
-  destruct (TotalOrder_Total a2 a3).
-  rewrite p.
-  reflexivity.
-  destruct s.
-    assert (a2 = a3).
-	  apply TotalOrder_Antisymmetric; assumption. 
-	  rewrite X. reflexivity.
-	  reflexivity.
-   	cbn. destruct (TotalOrder_Total a2 a3).
-   	rewrite p.
-    	reflexivity.
-    	destruct s.
-    	assert (a2 = a3).
-    	  apply TotalOrder_Antisymmetric; assumption.
-    	  rewrite X. reflexivity. reflexivity.
-  - cbn. intros R1 R2. 
-  destruct R1 as [La1 HR1].
-  destruct HR1 as [HR1E | HR1S]. 
-  destruct R2 as [La2 HR2].
-  destruct HR2 as [HR2E | HR2S].
-  reflexivity.
-  reflexivity.
-  destruct R2 as [La2 HR2].
-  destruct HR2 as [HR2E | HR2S].
-  reflexivity.
-  destruct HR1S as [a1 Ha1].
-  destruct HR2S as [a2 Ha2].
-  destruct (TotalOrder_Total a1 a2).
-  rewrite p.
-  destruct (TotalOrder_Total a2 a2).
-  reflexivity.
-  destruct s; reflexivity.
-	destruct s.
-	destruct (TotalOrder_Total a2 a1).
-	rewrite p.
-	reflexivity.
-	destruct s.
-	assert (a1 = a2).
-	apply TotalOrder_Antisymmetric; assumption.
-	rewrite X.
-	reflexivity.
-	reflexivity.
-	destruct (TotalOrder_Total a2 a1).
-	rewrite p.
-	reflexivity.
-	destruct s.
-	reflexivity.
-		assert (a1 = a2).
-	apply TotalOrder_Antisymmetric; assumption.
-	rewrite X.
-	reflexivity.
-  - cbn. intro R. destruct R as [La HR].
-  destruct HR. rewrite <- p. reflexivity.
-  destruct s as [a1 H].
-  apply (path_sigma' _  H^).
-  rewrite transport_sum.
-  f_ap.
-  rewrite transport_sigma.
-  simpl.
-  simple refine (path_sigma' _ _ _ ).
-  apply transport_const.
-  apply set_path2.
-
-  - intros R. cbn. 
-  destruct R as [ R  HR].
-  destruct HR as [HE | Ha ].
-  rewrite <- HE. reflexivity.
-  destruct Ha as [a Ha].
-  apply (path_sigma' _  Ha^).
-  rewrite transport_sum.
-  f_ap.
-  rewrite transport_sigma.
-  simpl.
-  simple refine (path_sigma' _ _ _ ).
-  apply transport_const.
-  apply set_path2.
-  - cbn. intro. 
-  destruct (TotalOrder_Total x x).
-  reflexivity.
-  destruct s.
-  reflexivity.
-  reflexivity.
-Defined.
-*)

FiniteSets/prelude.v

@@ -1,8 +1,6 @@
+(** Some general prerequisities in homotopy type theory. *)
 Require Import HoTT.
 
-(* Lemmas from this file do not belong in this project. *)
-(* Some of them should probably be in the HoTT library? *)
-
 Lemma ap_inl_path_sum_inl {A B} (x y : A) (p : inl x = inl y) :
   ap inl (path_sum_inl B p) = p.
 Proof.
@@ -11,13 +9,17 @@ Proof.
   destruct (path_sum_inl B p).
   reflexivity.
 Defined.
+
 Lemma ap_equiv {A B} (f : A <~> B) {x y : A} (p : x = y) :
   ap (f^-1 o f) p = eissect f x @ p @ (eissect f y)^.
-Proof. destruct p. hott_simpl. Defined.
+Proof.
+  destruct p.
+  hott_simpl.
+Defined.
 
 Global Instance hprop_lem `{Univalence} (T : Type) (Ttrunc : IsHProp T) : IsHProp (T + ~T).
-  Proof.
+Proof.
   apply (equiv_hprop_allpath _)^-1.
   intros [x | nx] [y | ny] ; try f_ap ; try (apply Ttrunc) ; try contradiction.
   - apply equiv_hprop_allpath. apply _.
-  Defined.
+Defined.

FiniteSets/subobjects/b_finite.v

@@ -1,7 +1,6 @@
 (* Bishop-finiteness is that "default" notion of finiteness in the HoTT library *)
-Require Import HoTT HitTactics plumbing.
+Require Import HoTT HitTactics.
-Require Import Sub notation variations.k_finite.
+Require Import sub subobjects.k_finite FSets prelude.
-Require Import fsets.properties fsets.monad.
 
 Section finite_hott.
   Variable (A : Type).
@@ -322,7 +321,7 @@ Section bfin_kfin.
       apply Kf_unfold in IH.
       destruct IH as [X HX].
       apply Kf_unfold.
-      exists ((ffmap inl X) ∪ {|inr tt|}); simpl.
+      exists ((fmap FSet inl X) ∪ {|inr tt|}); simpl.
       intros [a | []]; apply tr.
       + left.
         apply fmap_isIn.
@@ -380,7 +379,6 @@ Section kfin_bfin.
         { intros HXY. rewrite HXY.
           by apply IHn. }
         apply path_forall. intro a.
-        unfold union, sub_union, lattice.max_fun.
         apply path_iff_hprop.
         * intros Ha.
           strip_truncations.

FiniteSets/subobjects/enumerated.v

@@ -1,9 +1,8 @@
 (* Enumerated finite sets *)
 Require Import HoTT HitTactics.
-Require Import disjunction Sub.
+Require Import sub prelude FSets list_representation subobjects.k_finite
-Require Import representations.cons_repr representations.definition.
+        list_representation.isomorphism
-Require Import variations.k_finite.
+        lattice_interface lattice_examples.
-From fsets Require Import operations isomorphism properties_decidable operations_decidable.
 
 Fixpoint listExt {A} (ls : list A) : Sub A := fun x =>
   match ls with

FiniteSets/subobjects/k_finite.v

@@ -1,5 +1,5 @@
 Require Import HoTT HitTactics.
-Require Import lattice representations.definition fsets.operations extensionality Sub fsets.properties fsets.monad.
+Require Import sub lattice_interface lattice_examples FSets.
 
 Section k_finite.
 
@@ -125,7 +125,7 @@ Section k_properties.
   Proof.
     intros HX. apply Kf_unfold. apply Kf_unfold in HX.
     destruct HX as [Xf HXf].
-    exists (ffmap f Xf).
+    exists (fmap FSet f Xf).
     intro y.
     pose (x' := center (merely (hfiber f y))).
     simple refine (@Trunc_rec (-1) (hfiber f y) _ _ _ x'). clear x'; intro x.
@@ -168,7 +168,7 @@ Section alternative_definition.
   Local Ltac help_solve :=
     repeat (let x := fresh in intro x ; destruct x) ; intros
     ; try (simple refine (path_sigma _ _ _ _ _)) ; try (apply path_ishprop) ; simpl
-    ; unfold union, Sub.sub_union, max_fun
+    ; unfold union, sub_union, max_fun
     ; apply path_forall
     ; intro z
     ; eauto with lattice_hints typeclass_instances.