# Duality and Serre functor in homotopy categories

## TL;DR

This paper establishes a duality between certain homotopy categories of modules over coherent rings and artin algebras, leading to the existence of Serre functors and Auslander-Reiten triangles in these categories.

## Contribution

It introduces a duality between homotopy categories of modules over coherent rings and artin algebras, and shows the existence of Serre functors in these categories.

## Key findings

- Duality between homotopy categories for coherent rings and artin algebras.
- Existence of Serre functor in the category of acyclic complexes.
- Presence of Auslander-Reiten triangles in these categories.

## Abstract

For a (right and left) coherent ring $A$, we show that there exists a duality between homotopy categories ${\mathbb{K}}^{{\rm{b}}}({\rm mod}{\mbox{-}}A^{{\rm op}})$ and ${\mathbb{K}}^{{\rm{b}}}({\rm mod}{\mbox{-}}A)$. If $A=\Lambda$ is an artin algebra of finite global dimension, this duality restricts to a duality between their subcategories of acyclic complexes, ${\mathbb{K}}^{{\rm{b}}}_{\rm ac}({\rm mod}{\mbox{-}}\Lambda^{\rm op})$ and ${\mathbb{K}}^{{\rm{b}}}_{\rm ac}({\rm mod}{\mbox{-}}\Lambda).$ As a result, it will be shown that, in this case, ${\mathbb{K}}_{\rm ac}^{{\rm{b}}}({\rm mod}{\mbox{-}}\Lambda)$ admits a Serre functor and hence has Auslander-Reiten triangles.