Suppose that S is a space. There is an injective and a projective model structure for the resulting category of spaces with S-action, and both are easily derived. These model structures are special cases of model structures for presheaf-valued diagrams $X$ defined on a fixed presheaf of categories E which is enriched in simplicial sets.

Varying the parameter category object E (or parameter space S) along with the diagrams X up to weak equivalence requires model structures for E-diagrams having weak equivalences defined by homotopy colimits, and a generalization of Thomason's model structure for small categories to a model structure for presheaves of simplicial categories.

Keywords: model structures, presheaves of categories, diagrams

2010 MSC: Primary 18F20; Secondary 18G30, 55U35

*Theory and Applications of Categories,*
Vol. 28, 2013,
No. 11, pp 269-303.

Published 2013-05-16.

http://www.tac.mta.ca/tac/volumes/28/11/28-11.dvi

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