Some adjoints in homotopy categories

Abstract

Let $R$ be a ring. In a previous paper [11] we found a new description for the category $\mathbf{K}(R\text{-Proj})$; it is equivalent to the Verdier quotient $\mathbf{K}(R\text{-Flat})/{\mathscr S}$, for some suitable $\mathscr{S}\subset\mathbf{K}(R\text{-Flat})$. In this article we show that the quotient map from $\mathbf{K}(R\text{-Flat})$ to $\mathbf{K}(R\text{-Flat})/\mathscr{S}$ always has a right adjoint. This gives a new, fully faithful embedding of $\mathbf{K}(R\text{-Proj})$ into $\mathbf{K}(R\text{-Flat})$. Its virtue is that it generalizes to nonaffine schemes.

Authors

Amnon Neeman

Centre for Mathematics and its Applications
Mathematical Sciences Institute
John Dedman Building
The Australian National University
Canberra, ACT 0200
AUSTRALIA