model category, model $\infty$-category
Definitions
Morphisms
Universal constructions
Refinements
Producing new model structures
Presentation of $(\infty,1)$-categories
Model structures
for $\infty$-groupoids
on chain complexes/model structure on cosimplicial abelian groups
related by the Dold-Kan correspondence
for equivariant $\infty$-groupoids
for rational $\infty$-groupoids
for rational equivariant $\infty$-groupoids
for $n$-groupoids
for $\infty$-groups
for $\infty$-algebras
general $\infty$-algebras
specific $\infty$-algebras
for stable/spectrum objects
for $(\infty,1)$-categories
for stable $(\infty,1)$-categories
for $(\infty,1)$-operads
for $(n,r)$-categories
for $(\infty,1)$-sheaves / $\infty$-stacks
The global model structure on simplicial presheaves $[C^{op}, sSet_{Quillen}]$ on a small category $C$ is the global model structure on functors on $C$ with values in $sSet_{Quillen}$, the standard model structure on simplicial sets.
It presented the (∞,1)-category of (∞,1)-functors from $C^{op}$ to ∞Grpd, hence the (∞,1)-category of (∞,1)-presheaves on $C$.
The left Bousfield localizations of $[C^{op}, sSet]_{proj}$ are, up to Quillen equivalence, precisely the combinatorial model categories.
In particular, if $C$ carries the structure of a site, then
the left Bousfield localization of $[C^{op}, sSet_{Quillen}]$ at Cech covers is the Cech model structure on simplicial presheaves;
the left Bousfield localization at hypercovers is the local model structure on simplicial presheaves.
These localizations present the topological localization and hypercompletion of the (∞,1)-topos of $(\infty,1)$-presheaves on $C$ to the corresponding (∞,1)-topos of (∞,1)-sheaves/∞-stacks on $C$.
In every global model structure on simplicial presheaves on $C$ the weak equivalences are objectwise those with respect to the standard model structure on simplicial sets.
A morphism $f : A \to B$ in $[C^{op}, SSet]$ is, thus, a weak equivalence with respect to a global model structure precisely if for all $U \in Obj(C)$ the morphism
is a weak equivalence of simplicial set (i.e. a morphism inducing isomorphisms of simplicial homotopy groups).
There are several choices for how to extend this notion of weak equivalences to an entire model category structure. The two common extreme choices are
the global projective model structure has as fibrations the objectwise fibrations of the standard model structure on simplicial sets (i.e. the Kan fibrations);
the global injective model structure has as cofibrations the objectwise cofibrations with respect to the standard model structure on simplicial sets (i.e. the monomorphisms).
The other class of morphisms (cofibrations / fibrations) is in each case fixed by the corresponding lifting property.
See also model structure on simplicial presheaves.
The global projective model structure is originally due to
The fact that the global injective model structure yields a proper simplicial cofibrantly generated model category is originally due to
The fact that the global projective structure yields a proper simplicial cellular model category is due to Hirschhorn-Bousfield-Kan-Quillen
A quick review of these facts is on the first few pages of
Details on the projective global model structure is in
Last revised on August 23, 2023 at 17:18:44. See the history of this page for a list of all contributions to it.