Change of Enrichment for Monoidal Model Categories

Abstract

A classical theorem of category theory says that given an adjunction between monoidal categories with lax monoidal right adjoint, there is an induced adjunction between categories of enriched categories. We extend this result to monoidal model categories (with some model categorical assumptions), improving on previous theorems which required the derived left adjoint to be strong monoidal. As an application, we consider the category of chain complexes over a varying groupoid of operators, equipped with two different monoidal structures: the standard tensor product, and the cartesian product. We show that both of these products yield monoidal model categories, and use our theorems to reproduce the square-zero extensions adjunction for augmented dg-categories.