The derived category with respect to a generator

Abstract

Consider a Grothendieck category $\mathcal{G}$ along with a choice of generator $G$, or equivalently a generating set $\{G_i\}$. We introduce the derived category $\mathcal{D}(G)$, which kills all $G$-acyclic complexes, by putting a suitable model structure on the category of chain complexes. It follows that the category $\mathcal{D}(G)$ is always a well-generated triangulated category. It is compactly generated whenever the generating set $\{G_i\}$ has each $G_i$ finitely presented, and in this case we show that two recollement situations hold. The first is when passing from the homotopy category $K(\mathcal{G})$ to $\mathcal{D}(G)$. The second is a $G$-derived analog to the recollement of Krause. We illustrate with several examples ranging from pure and clean derived categories to quasi-coherent sheaves on the projective line $P^1(k)$.