Relative Higher Homology and Representation Theory

Higher homological algebra, basically done in the framework of an $n$-cluster tilting subcategory $\mathcal{M}$ of an abelian category $\mathcal{A}$, has been the topic of several recent researches. In this paper, we study a relative version, in the sense of Auslander-Solberg, of the higher homological algebra. To this end, we consider an additive sub-bifunctor $F$ of $\mathrm{Ext}^n_{\mathcal{M}}( -,-)$ as the basis of our relative theory. This, in turn, specifies a collection of $n$-exact sequences in $\mathcal{M}$, which allows us to delve into the relative higher homological algebra. Our results include a proof of the relative $n$-Auslander-Reiten duality formula, as well as an exploration of relative Grothendieck groups, among other results. As an application, we provide necessary and sufficient conditions for $\mathcal{M}$ to be of finite type.