Library UniMath.CategoryTheory.TwoSidedDisplayedCats.Examples.Comma
Require Import UniMath.Foundations.All.
Require Import UniMath.MoreFoundations.All.
Require Import UniMath.CategoryTheory.Core.Categories.
Require Import UniMath.CategoryTheory.Core.Functors.
Require Import UniMath.CategoryTheory.Core.Isos.
Require Import UniMath.CategoryTheory.TwoSidedDisplayedCats.TwoSidedDispCat.
Require Import UniMath.CategoryTheory.TwoSidedDisplayedCats.Isos.
Require Import UniMath.CategoryTheory.TwoSidedDisplayedCats.Univalence.
Require Import UniMath.CategoryTheory.TwoSidedDisplayedCats.Discrete.
Require Import UniMath.CategoryTheory.TwoSidedDisplayedCats.TwoSidedFibration.
Local Open Scope cat.
Section CommaTwoSidedDispCat.
Context {C₁ C₂ C₃ : category}
(F : C₁ ⟶ C₃)
(G : C₂ ⟶ C₃).
Require Import UniMath.MoreFoundations.All.
Require Import UniMath.CategoryTheory.Core.Categories.
Require Import UniMath.CategoryTheory.Core.Functors.
Require Import UniMath.CategoryTheory.Core.Isos.
Require Import UniMath.CategoryTheory.TwoSidedDisplayedCats.TwoSidedDispCat.
Require Import UniMath.CategoryTheory.TwoSidedDisplayedCats.Isos.
Require Import UniMath.CategoryTheory.TwoSidedDisplayedCats.Univalence.
Require Import UniMath.CategoryTheory.TwoSidedDisplayedCats.Discrete.
Require Import UniMath.CategoryTheory.TwoSidedDisplayedCats.TwoSidedFibration.
Local Open Scope cat.
Section CommaTwoSidedDispCat.
Context {C₁ C₂ C₃ : category}
(F : C₁ ⟶ C₃)
(G : C₂ ⟶ C₃).
1. Definition via two-sided displayed categories
Definition comma_twosided_disp_cat_ob_mor
: twosided_disp_cat_ob_mor C₁ C₂.
Show proof.
Definition comma_twosided_disp_cat_id_comp
: twosided_disp_cat_id_comp comma_twosided_disp_cat_ob_mor.
Show proof.
Definition comma_twosided_disp_cat_data
: twosided_disp_cat_data C₁ C₂.
Show proof.
Definition isaprop_comma_twosided_mor
{x₁ x₂ : C₁}
{y₁ y₂ : C₂}
(xy₁ : comma_twosided_disp_cat_data x₁ y₁)
(xy₂ : comma_twosided_disp_cat_data x₂ y₂)
(f : x₁ --> x₂)
(g : y₁ --> y₂)
: isaprop (xy₁ -->[ f ][ g ] xy₂).
Show proof.
Definition comma_twosided_disp_cat_axioms
: twosided_disp_cat_axioms comma_twosided_disp_cat_data.
Show proof.
Definition comma_twosided_disp_cat
: twosided_disp_cat C₁ C₂.
Show proof.
: twosided_disp_cat_ob_mor C₁ C₂.
Show proof.
simple refine (_ ,, _).
- exact (λ x y, F x --> G y).
- exact (λ x₁ x₂ y₁ y₂ h₁ h₂ f g, #F f · h₂ = h₁ · #G g).
- exact (λ x y, F x --> G y).
- exact (λ x₁ x₂ y₁ y₂ h₁ h₂ f g, #F f · h₂ = h₁ · #G g).
Definition comma_twosided_disp_cat_id_comp
: twosided_disp_cat_id_comp comma_twosided_disp_cat_ob_mor.
Show proof.
split.
- intros x y xy ; cbn.
rewrite !functor_id.
rewrite id_left, id_right.
apply idpath.
- intros x₁ x₂ x₃ y₁ y₂ y₃ h₁ h₂ h₃ f₁ f₂ g₁ g₂ hh₁ hh₂ ; cbn in *.
rewrite !functor_comp.
rewrite !assoc'.
rewrite hh₂.
rewrite !assoc.
apply maponpaths_2.
exact hh₁.
- intros x y xy ; cbn.
rewrite !functor_id.
rewrite id_left, id_right.
apply idpath.
- intros x₁ x₂ x₃ y₁ y₂ y₃ h₁ h₂ h₃ f₁ f₂ g₁ g₂ hh₁ hh₂ ; cbn in *.
rewrite !functor_comp.
rewrite !assoc'.
rewrite hh₂.
rewrite !assoc.
apply maponpaths_2.
exact hh₁.
Definition comma_twosided_disp_cat_data
: twosided_disp_cat_data C₁ C₂.
Show proof.
simple refine (_ ,, _).
- exact comma_twosided_disp_cat_ob_mor.
- exact comma_twosided_disp_cat_id_comp.
- exact comma_twosided_disp_cat_ob_mor.
- exact comma_twosided_disp_cat_id_comp.
Definition isaprop_comma_twosided_mor
{x₁ x₂ : C₁}
{y₁ y₂ : C₂}
(xy₁ : comma_twosided_disp_cat_data x₁ y₁)
(xy₂ : comma_twosided_disp_cat_data x₂ y₂)
(f : x₁ --> x₂)
(g : y₁ --> y₂)
: isaprop (xy₁ -->[ f ][ g ] xy₂).
Show proof.
Definition comma_twosided_disp_cat_axioms
: twosided_disp_cat_axioms comma_twosided_disp_cat_data.
Show proof.
repeat split.
- intro ; intros.
apply isaprop_comma_twosided_mor.
- intro ; intros.
apply isaprop_comma_twosided_mor.
- intro ; intros.
apply isaprop_comma_twosided_mor.
- intro ; intros.
apply isasetaprop.
apply isaprop_comma_twosided_mor.
- intro ; intros.
apply isaprop_comma_twosided_mor.
- intro ; intros.
apply isaprop_comma_twosided_mor.
- intro ; intros.
apply isaprop_comma_twosided_mor.
- intro ; intros.
apply isasetaprop.
apply isaprop_comma_twosided_mor.
Definition comma_twosided_disp_cat
: twosided_disp_cat C₁ C₂.
Show proof.
simple refine (_ ,, _).
- exact comma_twosided_disp_cat_data.
- exact comma_twosided_disp_cat_axioms.
- exact comma_twosided_disp_cat_data.
- exact comma_twosided_disp_cat_axioms.
2. Discreteness and univalence
Definition comma_twosided_disp_cat_is_iso
: all_disp_mor_iso comma_twosided_disp_cat.
Show proof.
Definition is_univalent_comma_twosided_disp_cat
: is_univalent_twosided_disp_cat comma_twosided_disp_cat.
Show proof.
Definition discrete_comma_twosided_disp_cat
: discrete_twosided_disp_cat comma_twosided_disp_cat.
Show proof.
: all_disp_mor_iso comma_twosided_disp_cat.
Show proof.
intro ; intros.
simple refine (_ ,, _ ,, _) ; cbn in *.
- rewrite !functor_on_inv_from_z_iso.
use z_iso_inv_on_right.
rewrite assoc.
use z_iso_inv_on_left ; cbn.
exact fg.
- apply isaprop_comma_twosided_mor.
- apply isaprop_comma_twosided_mor.
simple refine (_ ,, _ ,, _) ; cbn in *.
- rewrite !functor_on_inv_from_z_iso.
use z_iso_inv_on_right.
rewrite assoc.
use z_iso_inv_on_left ; cbn.
exact fg.
- apply isaprop_comma_twosided_mor.
- apply isaprop_comma_twosided_mor.
Definition is_univalent_comma_twosided_disp_cat
: is_univalent_twosided_disp_cat comma_twosided_disp_cat.
Show proof.
intros x₁ x₂ y₁ y₂ p₁ p₂ xy₁ xy₂.
induction p₁, p₂ ; cbn.
use isweqimplimpl.
- intros f.
pose (p := pr1 f) ; cbn in p.
rewrite !functor_id in p.
rewrite id_left, id_right in p.
exact (!p).
- apply homset_property.
- use isaproptotal2.
+ intro.
apply isaprop_is_iso_twosided_disp.
+ intros.
apply homset_property.
induction p₁, p₂ ; cbn.
use isweqimplimpl.
- intros f.
pose (p := pr1 f) ; cbn in p.
rewrite !functor_id in p.
rewrite id_left, id_right in p.
exact (!p).
- apply homset_property.
- use isaproptotal2.
+ intro.
apply isaprop_is_iso_twosided_disp.
+ intros.
apply homset_property.
Definition discrete_comma_twosided_disp_cat
: discrete_twosided_disp_cat comma_twosided_disp_cat.
Show proof.
repeat split.
- intro ; intros.
apply homset_property.
- exact comma_twosided_disp_cat_is_iso.
- exact is_univalent_comma_twosided_disp_cat.
- intro ; intros.
apply homset_property.
- exact comma_twosided_disp_cat_is_iso.
- exact is_univalent_comma_twosided_disp_cat.
3. It is a two-sided fibration
Definition comma_twosided_opcleaving
: twosided_opcleaving comma_twosided_disp_cat.
Show proof.
Definition comma_twosided_cleaving
: twosided_cleaving comma_twosided_disp_cat.
Show proof.
Definition comma_twosided_fibration
: twosided_fibration comma_twosided_disp_cat.
Show proof.
: twosided_opcleaving comma_twosided_disp_cat.
Show proof.
intros x₁ x₂ x₃ f g ; cbn in *.
simple refine (f · #G g ,, _ ,, _) ; cbn.
- rewrite functor_id.
rewrite id_left.
apply idpath.
- intros x₄ x₅ h k l p.
use iscontraprop1.
+ use invproofirrelevance.
intros φ₁ φ₂.
use subtypePath.
{
intro.
apply isaset_disp_mor.
}
apply isaprop_comma_twosided_mor.
+ cbn in *.
simple refine (_ ,, _).
* rewrite id_left, functor_comp, assoc in p.
exact p.
* apply isaprop_comma_twosided_mor.
simple refine (f · #G g ,, _ ,, _) ; cbn.
- rewrite functor_id.
rewrite id_left.
apply idpath.
- intros x₄ x₅ h k l p.
use iscontraprop1.
+ use invproofirrelevance.
intros φ₁ φ₂.
use subtypePath.
{
intro.
apply isaset_disp_mor.
}
apply isaprop_comma_twosided_mor.
+ cbn in *.
simple refine (_ ,, _).
* rewrite id_left, functor_comp, assoc in p.
exact p.
* apply isaprop_comma_twosided_mor.
Definition comma_twosided_cleaving
: twosided_cleaving comma_twosided_disp_cat.
Show proof.
intros x₁ x₂ x₃ f g ; cbn in *.
simple refine (#F g · f ,, _ ,, _) ; cbn.
- rewrite functor_id.
rewrite id_right.
apply idpath.
- intros x₄ x₅ h k l p.
use iscontraprop1.
+ use invproofirrelevance.
intros φ₁ φ₂.
use subtypePath.
{
intro.
apply isaset_disp_mor.
}
apply isaprop_comma_twosided_mor.
+ cbn in *.
simple refine (_ ,, _).
* rewrite id_right, functor_comp, assoc' in p.
exact p.
* apply isaprop_comma_twosided_mor.
simple refine (#F g · f ,, _ ,, _) ; cbn.
- rewrite functor_id.
rewrite id_right.
apply idpath.
- intros x₄ x₅ h k l p.
use iscontraprop1.
+ use invproofirrelevance.
intros φ₁ φ₂.
use subtypePath.
{
intro.
apply isaset_disp_mor.
}
apply isaprop_comma_twosided_mor.
+ cbn in *.
simple refine (_ ,, _).
* rewrite id_right, functor_comp, assoc' in p.
exact p.
* apply isaprop_comma_twosided_mor.
Definition comma_twosided_fibration
: twosided_fibration comma_twosided_disp_cat.
Show proof.
simple refine (_ ,, _ ,, _).
- exact comma_twosided_opcleaving.
- exact comma_twosided_cleaving.
- intro ; intros.
apply comma_twosided_disp_cat_is_iso.
End CommaTwoSidedDispCat.- exact comma_twosided_opcleaving.
- exact comma_twosided_cleaving.
- intro ; intros.
apply comma_twosided_disp_cat_is_iso.
4. The representable profunctors
Definition left_repr_twosided_disp_cat
{C₁ C₂ : category}
(F : C₁ ⟶ C₂)
: twosided_disp_cat C₁ C₂
:= comma_twosided_disp_cat F (functor_identity _).
Definition right_repr_twosided_disp_cat
{C₁ C₂ : category}
(F : C₁ ⟶ C₂)
: twosided_disp_cat C₂ C₁
:= comma_twosided_disp_cat (functor_identity _) F.
{C₁ C₂ : category}
(F : C₁ ⟶ C₂)
: twosided_disp_cat C₁ C₂
:= comma_twosided_disp_cat F (functor_identity _).
Definition right_repr_twosided_disp_cat
{C₁ C₂ : category}
(F : C₁ ⟶ C₂)
: twosided_disp_cat C₂ C₁
:= comma_twosided_disp_cat (functor_identity _) F.