Library UniMath.CategoryTheory.categories.setwith2binops

Category of setswith2binops

Contents

  • setwith2binops precategory
  • setwith2binops category

Require Import UniMath.Foundations.PartD.
Require Import UniMath.Foundations.Propositions.
Require Import UniMath.Foundations.Sets.
Require Import UniMath.Foundations.UnivalenceAxiom.

Require Import UniMath.Algebra.BinaryOperations.

Require Import UniMath.CategoryTheory.Core.Categories.
Require Import UniMath.CategoryTheory.Core.Isos.
Require Import UniMath.CategoryTheory.Core.Univalence.
Local Open Scope cat.

Precategory of setwith2binops

Section def_setwith2binop_precategory.

  Definition setwith2binop_fun_space (A B : setwith2binop) : hSet :=
    hSetpair (twobinopfun A B) (isasettwobinopfun A B).

  Definition setwith2binop_precategory_ob_mor : precategory_ob_mor :=
    tpair (λ ob : UU, ob -> ob -> UU) setwith2binop
          (λ A B : setwith2binop, setwith2binop_fun_space A B).

  Definition setwith2binop_precategory_data : precategory_data :=
    precategory_data_pair
      setwith2binop_precategory_ob_mor
      (λ (X : setwith2binop), ((idtwobinopiso X) : twobinopfun X X))
      (fun (X Y Z : setwith2binop) (f : twobinopfun X Y) (g : twobinopfun Y Z)
       => twobinopfuncomp f g).

  Local Lemma setwith2binop_id_left (X Y : setwith2binop) (f : twobinopfun X Y) :
    twobinopfuncomp (idtwobinopiso X) f = f.
  Show proof.
    use twobinopfun_paths. use idpath.
  Opaque setwith2binop_id_left.

  Local Lemma setwith2binop_id_right (X Y : setwith2binop) (f : twobinopfun X Y) :
    twobinopfuncomp f (idtwobinopiso Y) = f.
  Show proof.
    use twobinopfun_paths. use idpath.
  Opaque setwith2binop_id_right.

  Local Lemma setwith2binop_assoc (X Y Z W : setwith2binop) (f : twobinopfun X Y)
             (g : twobinopfun Y Z) (h : twobinopfun Z W) :
    twobinopfuncomp f (twobinopfuncomp g h) = twobinopfuncomp (twobinopfuncomp f g) h.
  Show proof.
    use twobinopfun_paths. use idpath.
  Opaque setwith2binop_assoc.

  Lemma is_precategory_setwith2binop_precategory_data :
    is_precategory setwith2binop_precategory_data.
  Show proof.
    use mk_is_precategory.
    - intros a b f. use setwith2binop_id_left.
    - intros a b f. use setwith2binop_id_right.
    - intros a b c d f g h. use setwith2binop_assoc.
    - intros a b c d f g h. apply pathsinv0, setwith2binop_assoc.

  Definition setwith2binop_precategory : precategory :=
    mk_precategory setwith2binop_precategory_data is_precategory_setwith2binop_precategory_data.

  Lemma has_homsets_setwith2binop_precategory : has_homsets setwith2binop_precategory.
  Show proof.
    intros X Y. use isasettwobinopfun.

End def_setwith2binop_precategory.

Category of setwith2binops

Section def_setwith2binop_category.

(twobinopiso X Y) ≃ (iso X Y)


  Lemma setwith2binop_iso_is_equiv (A B : ob setwith2binop_precategory) (f : iso A B) :
    isweq (pr1 (pr1 f)).
  Show proof.
    use isweq_iso.
    - exact (pr1twobinopfun _ _ (inv_from_iso f)).
    - intros x.
      use (toforallpaths _ _ _ (subtypeInjectivity _ _ _ _ (iso_inv_after_iso f)) x).
      intros x0. use isapropistwobinopfun.
    - intros x.
      use (toforallpaths _ _ _ (subtypeInjectivity _ _ _ _ (iso_after_iso_inv f)) x).
      intros x0. use isapropistwobinopfun.
  Opaque setwith2binop_iso_is_equiv.

  Lemma setwith2binop_iso_equiv (X Y : ob setwith2binop_precategory) : iso X Y -> twobinopiso X Y.
  Show proof.
    intro f.
    use twobinopisopair.
    - exact (weqpair (pr1 (pr1 f)) (setwith2binop_iso_is_equiv X Y f)).
    - exact (pr2 (pr1 f)).

  Lemma setwith2binop_equiv_is_iso (X Y : ob setwith2binop_precategory) (f : twobinopiso X Y) :
    @is_iso setwith2binop_precategory X Y (twobinopfunpair (pr1 (pr1 f)) (pr2 f)).
  Show proof.
    use is_iso_qinv.
    - exact (twobinopfunpair (pr1 (pr1 (invtwobinopiso f))) (pr2 (invtwobinopiso f))).
    - use mk_is_inverse_in_precat.
      + use twobinopfun_paths. use funextfun. intros x. use homotinvweqweq.
      + use twobinopfun_paths. use funextfun. intros y. use homotweqinvweq.
  Opaque setwith2binop_equiv_is_iso.

  Lemma setwith2binop_equiv_iso (X Y : ob setwith2binop_precategory) : twobinopiso X Y -> iso X Y.
  Show proof.
    intros f. exact (@isopair setwith2binop_precategory X Y (twobinopfunpair (pr1 (pr1 f)) (pr2 f))
                              (setwith2binop_equiv_is_iso X Y f)).

  Lemma setwith2binop_iso_equiv_is_equiv (X Y : setwith2binop_precategory) :
    isweq (setwith2binop_iso_equiv X Y).
  Show proof.
    use isweq_iso.
    - exact (setwith2binop_equiv_iso X Y).
    - intros x. use eq_iso. use twobinopfun_paths. use idpath.
    - intros y. use twobinopiso_paths. use subtypeEquality.
      + intros x0. use isapropisweq.
      + use idpath.
  Opaque setwith2binop_iso_equiv_is_equiv.

  Definition setwith2binop_iso_equiv_weq (X Y : ob setwith2binop_precategory) :
    (iso X Y) ≃ (twobinopiso X Y).
  Show proof.
    use weqpair.
    - exact (setwith2binop_iso_equiv X Y).
    - exact (setwith2binop_iso_equiv_is_equiv X Y).

  Lemma setwith2binop_equiv_iso_is_equiv (X Y : ob setwith2binop_precategory) :
    isweq (setwith2binop_equiv_iso X Y).
  Show proof.
    use isweq_iso.
    - exact (setwith2binop_iso_equiv X Y).
    - intros y. use twobinopiso_paths. use subtypeEquality.
      + intros x0. use isapropisweq.
      + use idpath.
    - intros x. use eq_iso. use twobinopfun_paths. use idpath.
  Opaque setwith2binop_equiv_iso_is_equiv.

  Definition setwith2binop_equiv_weq_iso (X Y : ob setwith2binop_precategory) :
    (twobinopiso X Y) ≃ (iso X Y).
  Show proof.
    use weqpair.
    - exact (setwith2binop_equiv_iso X Y).
    - exact (setwith2binop_equiv_iso_is_equiv X Y).

Category of setwith2binops


  Definition setwith2binop_precategory_isweq (X Y : ob setwith2binop_precategory) :
    isweq (λ p : X = Y, idtoiso p).
  Show proof.
    use (@isweqhomot
           (X = Y) (iso X Y)
           (pr1weq (weqcomp (setwith2binop_univalence X Y) (setwith2binop_equiv_weq_iso X Y)))
           _ _ (weqproperty (weqcomp (setwith2binop_univalence X Y)
                                     (setwith2binop_equiv_weq_iso X Y)))).
    intros e. induction e.
    use (pathscomp0 weqcomp_to_funcomp_app).
    use total2_paths_f.
    - use idpath.
    - use proofirrelevance. use isaprop_is_iso.
  Opaque setwith2binop_precategory_isweq.

  Definition setwith2binop_precategory_is_univalent : is_univalent setwith2binop_precategory.
  Show proof.
    use mk_is_univalent.
    - intros X Y. exact (setwith2binop_precategory_isweq X Y).
    - exact has_homsets_setwith2binop_precategory.

  Definition setwith2binop_category : univalent_category :=
    mk_category setwith2binop_precategory setwith2binop_precategory_is_univalent.

End def_setwith2binop_category.