nLab
model structure on sSet-categories

Context

Model category theory

model category

Definitions

Morphisms

Universal constructions

Refinements

Producing new model structures

Presentation of (,1)-categories

Model structures

for -groupoids

for ∞-groupoids

for n-groupoids

for -groups

for -algebras

general

specific

for stable/spectrum objects

for (,1)-categories

for stable (,1)-categories

for (,1)-operads

for (n,r)-categories

for (,1)-sheaves / -stacks

(,1)-Category theory

Contents

Idea

Depending on the chosen model category structure, the category sSet of simplicial sets may model ∞-groupoids (for the standard model structure on simplicial sets) or (∞,1)-categories in the form of quasi-categories (for the Joyal model structure) on SSet.

Accordingly, there are model category structures on sSet-categories that similarly model (n,r)-categories with r shifted up by 1:

Both are special cases of a model structure on enriched categories.

Model for (,1)-categories

Here we describe the model category structure on SSet Cat that makes it a model for the (∞,1)-category of (∞,1)-categories.

Definition An sSet-enriched functor F:CD between sSet-categories is called a weak equivalence precisely if

Such a morphism is also called a Dwyer-Kan weak equivalence after the work by Dwyer-Kan on simplicial localization.

Propositon A Quillen equivalence CD between model categories induces a Dwyer-Kan-equivalence LCLD between their simplicial localizations.

Proposition The category SSet Cat of small simplicially enriched categories carries the structure of a model category with

In particualar, the fibrant objects in this structure are the Kan complex-enriched categories, i.e. the strictly ∞-groupoid-enriched ones (see (n,r)-category).

The entries of the following table display models, model categories, and Quillen equivalences between these that present the (∞,1)-category of (∞,1)-categories (second table), of (∞,1)-operads (third table) and of 𝒪-monoidal (∞,1)-categories (fourth table).

general pattern
strict enrichment(∞,1)-category/(∞,1)-operad
enriched (∞,1)-categoryinternal (∞,1)-category
(∞,1)Cat
SimplicialCategorieshomotopy coherent nerveSimplicialSets/quasi-categoriesRelativeSimplicialSets
simplicial nerve
SegalCategoriesCompleteSegalSpaces
(∞,1)Operad
SimplicialOperadshomotopy coherent dendroidal nerveDendroidalSetsRelativeDendroidalSets
dendroidal nerve
SegalOperadsDendroidalCompleteSegalSpaces
𝒪Mon(∞,1)Cat
DendroidalCartesianFibrations

References

A model category structure on the category of sSet-categories with a fixed set of objects was first given in

  • William Dwyer, Dan Kan, Simplicial localization of categories , J. Pure and Applied Algebra 17 (3) (1980),

Dywer, Spalinski and later Rezk then pointed out that there ought to exist a model category structure on the collection of all sSet-categories that models the (∞,1)-category of (∞,1)-categories. This was then constructed in

A survey is in section 3 of

See also section A.3.2 of

Model for (,2)-categories

for the moment see (∞,2)-category for more on this

References

Section A.3 of

Also

Revised on June 8, 2013 14:47:52 by Urs Schreiber (66.46.90.198)