on chain complexes/model structure on cosimplicial abelian groups
related by the Dold-Kan correspondence
on algebras over an operad, on modules over an algebra over an operad
on dendroidal sets, for dendroidal complete Segal spaces, for dendroidal Cartesian fibrations
equivalences in/of -categories
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 shifted up by 1:
there is a model structure on -enriched categories whose fibrant objects are ∞-groupoid/Kan complex-enriched categories and which models (∞,1)-categories;
there is another model structure on sSet-categories whose fibrant objects are (∞,1)-category/quasi-category-enriched categories, and which model (∞,2)-categories.
Both are special cases of a model structure on enriched 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 between sSet-categories is called a weak equivalence precisely if
it is essentially surjective in that the induced functor of homotopy categories is an ordinary essentially surjective functor;
it is an -full and faithful functor in that for all objects the morphism
is a weak equivalence in the standard model structure on simplicial sets.
Such a morphism is also called a Dwyer-Kan weak equivalence after the work by Dwyer-Kan on simplicial localization.
Propositon A Quillen equivalence between model categories induces a Dwyer-Kan-equivalence between their simplicial localizations.
Proposition The category SSet Cat of small simplicially enriched categories carries the structure of a model category with
weak equivalences the Dwyer-Kan equivalences;
fibrations those sSet-enriched functors such that
for all the morphism is a fibration in the standard model structure on simplicial sets;
the induced functor on homotopy categories is an isofibration.
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 -monoidal (∞,1)-categories (fourth table).
A model category structure on the category of -categories with a fixed set of objects was first given in
Dywer, Spalinski and later Rezk then pointed out that there ought to exist a model category structure on the collection of all -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
for the moment see (∞,2)-category for more on this
Section A.3 of
Also