The Augmented simplex category #
This file defines the AugmentedSimplexCategory
as the category obtained by adding an initial
object to SimplexCategory
(using CategoryTheory.WithInitial
).
This definition provides a canonical full and faithful inclusion functor
inclusion : SimplexCategory ⥤ AugmentedSimplexCategory
.
We prove that functors out of AugmentedSimplexCategory
are equivalent to augmented cosimplicial
objects and that functors out of AugmentedSimplexCategoryᵒᵖ
are equivalent to augmented simplicial
objects, and we provide a translation of the main constrcutions on augmented (co)simplicial objects
(i.e drop
, point
and toArrow
) in terms of these equivalences.
TODOs #
- Define a monoidal structure on
AugmentedSimplexCategory
.
The AugmentedSimplexCategory
is the category obtained from SimplexCategory
by adjoining an
initial object.
Equations
Instances For
The canonical inclusion from SimplexCategory
to AugmentedSimplexCategory
.
Equations
Instances For
The equivalence between functors out of AugmentedSimplexCategory
and augmented
cosimplicial objects.
Equations
Instances For
Through the equivalence (AugmentedSimplexCategory ⥤ C) ≌ CosimplicialObject.Augmented C
,
dropping the augmentation corresponds to precomposition with
inclusion : SimplexCategory ⥤ AugmentedSimplexCategory
.
Equations
Instances For
Through the equivalence (AugmentedSimplexCategory ⥤ C) ≌ CosimplicialObject.Augmented C
,
taking the point of the augmentation corresponds to evaluation at the initial object.
Equations
Instances For
Through the equivalence (AugmentedSimplexCategory ⥤ C) ≌ CosimplicialObject.Augmented C
,
the arrow attached to the cosimplicial object is the one obtained by evaluation at the unique arrow
star ⟶ of [0]
.
Equations
Instances For
The equivalence between functors out of AugmentedSimplexCategory
and augmented simplicial
objects.
Equations
Instances For
Through the equivalence (AugmentedSimplexCategoryᵒᵖ ⥤ C) ≌ SimplicialObject.Augmented C
,
dropping the augmentation corresponds to precomposition with
inclusionᵒᵖ : SimplexCategoryᵒᵖ ⥤ AugmentedSimplexCategoryᵒᵖ
.
Equations
Instances For
Through the equivalence (AugmentedSimplexCategory ⥤ C) ≌ CosimplicialObject.Augmented C
,
taking the point of the augmentation corresponds to evaluation at the initial object.
Equations
Instances For
Through the equivalence (AugmentedSimplexCategory ⥤ C) ≌ CosimplicialObject.Augmented C
,
the arrow attached to the cosimplicial object is the one obtained by evaluation at the unique arrow
star ⟶ of [0]
.