Library UniMath.SubstitutionSystems.LamHSET

Instantiate the hypotheses of InitialHSS with Lam for HSET.

Written by: Anders Mörtberg, 2016

Require Import UniMath.Foundations.PartD.

Require Import UniMath.CategoryTheory.Core.Categories.
Require Import UniMath.CategoryTheory.Core.Functors.
Local Open Scope cat.
Require Import UniMath.CategoryTheory.FunctorCategory.
Require Import UniMath.CategoryTheory.whiskering.
Require Import UniMath.CategoryTheory.limits.binproducts.
Require Import UniMath.CategoryTheory.limits.bincoproducts.
Require Import UniMath.CategoryTheory.limits.terminal.
Require Import UniMath.CategoryTheory.limits.initial.
Require Import UniMath.CategoryTheory.FunctorAlgebras.
Require Import UniMath.CategoryTheory.PointedFunctors.
Require Import UniMath.CategoryTheory.PrecategoryBinProduct.
Require Import UniMath.SubstitutionSystems.Signatures.
Require Import UniMath.CategoryTheory.UnitorsAndAssociatorsForEndofunctors.
Require Import UniMath.CategoryTheory.Monads.Monads.
Require Import UniMath.SubstitutionSystems.BinSumOfSignatures.
Require Import UniMath.SubstitutionSystems.SubstitutionSystems.
Require Import UniMath.SubstitutionSystems.LamSignature.
Require Import UniMath.SubstitutionSystems.LiftingInitial_alt.
Require Import UniMath.SubstitutionSystems.MonadsFromSubstitutionSystems.
Require Import UniMath.SubstitutionSystems.Notation.
Local Open Scope subsys.

Require Import UniMath.CategoryTheory.limits.graphs.colimits.
Require Import UniMath.CategoryTheory.exponentials.
Require Import UniMath.CategoryTheory.categories.HSET.Core.
Require Import UniMath.CategoryTheory.categories.HSET.Limits.
Require Import UniMath.CategoryTheory.categories.HSET.Colimits.
Require Import UniMath.CategoryTheory.categories.HSET.Structures.
Require Import UniMath.CategoryTheory.Chains.All.

Section LamHSET.

Let Lam_S : Signature HSET has_homsets_HSET _ _ _ _ :=
  Lam_Sig HSET has_homsets_HSET TerminalHSET BinCoproductsHSET BinProductsHSET.

Local Notation "'EndHSET'":= ([HSET , HSET , has_homsets_HSET ]) .

Let hsEndC : has_homsets EndHSET := functor_category_has_homsets _ _ has_homsets_HSET.

Local Lemma is_omega_cocont_Lam_S : is_omega_cocont Lam_S.
Proof.
apply is_omega_cocont_Lam.
× apply is_omega_cocont_constprod_functor1.
  apply functor_category_has_homsets.
  apply (Exponentials_functor_HSET _ has_homsets_HSET).
× apply ColimsHSET_of_shape.
Defined.

Lemma Lam_Initial_HSET : Initial (precategory_FunctorAlg (Id_H _ _ BinCoproductsHSET Lam_S) hsEndC).
Proof.
use colimAlgInitial.
- apply (Initial_functor_precat _ _ InitialHSET).
- unfold Id_H, Const_plus_H.
  apply is_omega_cocont_BinCoproduct_of_functors.
  + apply functor_category_has_homsets.
  + apply is_omega_cocont_constant_functor; apply functor_category_has_homsets.
  + apply is_omega_cocont_Lam_S.
- apply ColimsFunctorCategory_of_shape; apply ColimsHSET_of_shape.
Defined.

Definition LamHSS_Initial_HSET : Initial (hss_precategory BinCoproductsHSET Lam_S).
Proof.
apply InitialHSS.
- apply InitialHSET.
- apply ColimsHSET_of_shape.
- apply is_omega_cocont_Lam_S.
Defined.

Definition LamMonad : Monad HSET.
Proof.
use Monad_from_hss.
- apply has_homsets_HSET.
- apply BinCoproductsHSET.
- apply Lam_S.
- apply LamHSS_Initial_HSET.
Defined.

End LamHSET.