arXiv subjects

J. Asadollahi

Publications and source records attributed to J. Asadollahi.

4 recordsLinked to original sources

arXiv2024

Strong Purity and Phantom Morphisms

Let $R$ be a commutative ring and $S \subseteq R$ be a multiplicative subset. We introduce and study the concept of $S$-purity based on the notion of $S$-strongly flat modules. The class of $S$-pure injective modules will be studied. We demonstrate that this class is enveloping and explore its closedness under extension. The concept of purity is closely connected to the existence of phantom maps. So we will delve into the study of the $S$-phantom morphisms. We will establish that the $S$-phantom ideal is a precovering ideal and examine the situations where it becomes a covering ideal. Finally, in the last section, we will investigate an ideal version of the `Optimistic Conjecture', raised by Positselski and Slávik.

math.AC↗

arXiv2022

Extending ($τ$-)tilting subcategories and (co)silting modules

Let $B$ be a finite dimensional algebra and $A=B[P_0]$ be the one-point extension algebra of $B$ with respect to the finitely generated projective $B$-module $P_0$. The categories of $B$-modules and $A$-modules are related by two adjoint functors $\mathcal{R}$ and $\mathcal{E}$, called the restriction and the extension functors, respectively. Based on the nice homological properties of these two functors, restriction and extension of some notions such as tilting and $τ$-tilting modules have been studied in the category of finitely presented modules, i.e. small mod. In this paper, we investigate the behaviour of tilting and support $τ$-tilting subcategories with respect to these two functors. Moreover, we investigate the restriction and the extension of special related modules such as finendo quasi-tilting modules, silting modules, and cosilting modules. Our studies will be done in the category of all modules, which will be called large Mod. Based on such study, in addition to the new results, classical results are extended, not only from modules to subcategories but also from small mod to large Mod.

math.RT↗

arXiv2017

Duality and Serre functor in homotopy categories

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

math.RT↗

arXiv2016

On relative derived categories

The paper is devoted to study some of the questions arises naturally in connection to the notion of relative derived categories. In particular, we study invariants of recollements involving relative derived categories, generalise two results of Happel by proving the existence of AR-triangles in Gorenstein derived categories, provide situations for which relative derived categories with respect to Gorenstein projective and Gorenstein injective modules are equivalent and finally study relations between the Gorenstein derived category of a quiver and its image under a reflection functor. Some interesting applications are provided.

math.RT↗