Model category structures on simplicial objects

Abstract

A general method for lifting weak factorization systems in a category S to model category structures on simplicial objects in S is described, analogously to the lifting of cotorsion pairs in Abelian categories to model category structures on chain complexes. This generalizes Quillen's original treatment of (projective) model category structures on simplicial objects. As a new application we show that there is always a model category structure on simplicial objects in the coproduct completion of any (even large) category S with finite limits, which - if S is small - defines the same homotopy theory as any global model category of simplicial pre-sheaves on S. If S is, in addition, extensive, a similar model category structure exists on simplicial objects in S itself. In any case the associated left derivator exists on all diagrams despite the lack of colimits in the original category.