arXiv subjects

Alexandra Zvonareva

Publications and source records attributed to Alexandra Zvonareva.

At least 19 recordsLinked to original sources

arXiv2026

Limits and colimits in silting theory with applications to the wall and chamber structure of an algebra

In this paper we consider a family of nested t-structures given by silting objects and construct a silting object corresponding to the intersection of aisles of these t-structures as a homotopy colimit. The dual construction for the cosilting case is given as a homotopy limit. The results are applied to construct two-term large silting objects corresponding to the numerical torsion pairs and the limiting walls in the wall and chamber structure of the real Grothendieck group of a finite dimensional algebra. In particular, in case the algebra is tame we can describe any numerical torsion pair in this way by combining our results with results of Plamondon and Yurikusa.

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arXiv2026

The shift-homological spectrum and parametrising kernels of rank functions

For any compactly generated triangulated category we introduce two topological spaces, the shift-spectrum and the shift-homological spectrum. We use them to parametrise a family of thick subcategories of the compact objects, which we call radical. These spaces can be viewed as non-monoidal analogues of the Balmer and homological spectra arising in tensor-triangular geometry: we prove that for monogenic tensor-triangulated categories the Balmer spectrum is a subspace of the shift-spectrum. To construct these analogues we utilise quotients of the module category, rather than the lattice theoretic methods which have been adopted in other approaches. We characterise radical thick subcategories and show in certain cases, such as the perfect derived categories of tame hereditary algebras or monogenic tensor-triangulated categories, that every thick subcategory is radical. We establish a close relationship between the shift-homological spectrum and the set of irreducible integral rank functions, and provide necessary and sufficient conditions for every radical thick subcategory to be given by an intersection of kernels of rank functions. In order to facilitate these results, we prove that both spaces we introduce may equivalently be described in terms of the Ziegler spectrum.

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arXiv2024

Derived equivalences of Brauer graph algebras

The aim of this short survey is to trace back the ingredients going into the derived equivalence classification of Brauer graph algebras and into the proof of the fact that these algebras are closed under derived equivalence.

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arXiv2023

A functorial approach to rank functions on triangulated categories

We study rank functions on a triangulated category $\mathcal{C}$ via its abelianisation $\operatorname{mod}\mathcal{C}$. We prove that every rank function on $\mathcal{C}$ can be interpreted as an additive function on $\operatorname{mod}\mathcal{C}$. As a consequence, every integral rank function has a unique decomposition into irreducible ones. Furthermore, we relate integral rank functions to a number of important concepts in the functor category $\operatorname{Mod}\mathcal{C}$. We study the connection between rank functions and functors from $\mathcal{C}$ to locally finite triangulated categories, generalising results by Chuang and Lazarev. In the special case $\mathcal{C}=\mathcal{T}^c$ for a compactly generated triangulated category $\mathcal{T}$, this connection becomes particularly nice, providing a link between rank functions on $\mathcal{C}$ and smashing localisations of $\mathcal{T}$. In this context, any integral rank function can be described using the composition length with respect to certain endofinite objects in $\mathcal{T}$. Finally, if $\mathcal{C}=\operatorname{per}(A)$ for a differential graded algebra $A$, we classify homological epimorphisms $A\to B$ with $\operatorname{per}(B)$ locally finite via special rank functions which we call idempotent.

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arXiv2022

Lattices of t-structures and thick subcategories for discrete cluster categories

We classify t-structures and thick subcategories in discrete cluster categories $\mathcal{C}(\mathcal{Z})$ of Dynkin type $A$, and show that the set of all t-structures on $\mathcal{C}(\mathcal{Z})$ is a lattice under inclusion of aisles, with meet given by their intersection. We show that both the lattice of t-structures on $\mathcal{C}(\mathcal{Z})$ obtained in this way and the lattice of thick subcategories of $\mathcal{C}(\mathcal{Z})$ are intimately related to the lattice of non-crossing partitions of type $A$. In particular, the lattice of equivalence classes of non-degenerate t-structures on such a category is isomorphic to the lattice of non-crossing partitions of a finite linearly ordered set.

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arXiv2022

Lifting and restricting t-structures

We explore the interplay between t-structures in the bounded derived category of finitely presented modules and the unbounded derived category of all modules over a coherent ring $A$ using homotopy colimits. More precisely, we show that every intermediate t-structure in $D^b(\operatorname{mod}(A))$ can be lifted to a compactly generated t-structure in $D(\operatorname{Mod}(A))$, by closing the aisle and the coaisle of the t-structure under directed homotopy colimits. Conversely, we provide necessary and sufficient conditions for a compactly generated t-structure in $D(\operatorname{Mod}(A))$ to restrict to an intermediate t-structure in $D^b(\operatorname{mod}(A))$, thus describing which t-structures can be obtained via lifting. We apply our results to the special case of HRS-t-structures. Finally, we discuss various applications to silting theory in the context of finite dimensional algebras.

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arXiv2022

Derived equivalence classification of Brauer graph algebras

We classify Brauer graph algebras up to derived equivalence by showing that the set of derived invariants introduced by Antipov is complete. These algebras first appeared in representation theory of finite groups and can be defined for any suitably decorated graph on an oriented surface. Motivated by the connection between Brauer graph algebras and gentle algebras we consider $A_{\infty}$-trivial extensions of partially wrapped Fukaya categories associated to surfaces with boundary. This construction naturally enlarges the class of Brauer graph algebras and provides a way to construct derived equivalences between Brauer graph algebras with the same derived invariants. As part of the proof we provide an interpretation of derived invariants of Brauer graph algebras as orbit invariants of line fields under the action of the mapping class group.

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arXiv2021

Brauer graph algebras are closed under derived equivalence

In this paper the class of Brauer graph algebras is proved to be closed under derived equivalence. For that we use the rank of the maximal torus of the identity component $Out^0(A)$ of the group of outer automorphisms of a symmetric stably biserial algebra $A$.

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arXiv2021

Functorially finite hearts, simple-minded systems in negative cluster categories, and noncrossing partitions

Let $Q$ be an acyclic quiver and $w \geq 1$ be an integer. Let $\mathsf{C}_{-w} (\mathbf{k} Q)$ be the $(-w)$-cluster category of $\mathbf{k} Q$. We show that there is a bijection between simple-minded collections in $\mathsf{D}^b (\mathbf{k} Q)$ lying in a fundamental domain of $\mathsf{C}_{-w} (\mathbf{k} Q)$ and $w$-simple-minded systems in $\mathsf{C}_{-w} (\mathbf{k} Q)$. This generalises the same result of Iyama-Jin in the case that $Q$ is Dynkin. A key step in our proof is the observation that the heart $\mathsf{H}$ of a bounded t-structure in a Hom-finite, Krull-Schmidt, $\mathbf{k}$-linear saturated triangulated category $\mathsf{D}$ is functorially finite in $\mathsf{D}$ if and only if $\mathsf{H}$ has enough injectives and enough projectives. We then establish a bijection between $w$-simple-minded systems in $\mathsf{C}_{-w} (\mathbf{k} Q)$ and positive $w$-noncrossing partitions of the corresponding Weyl group $W_Q$.

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arXiv2021

Lifting of recollements and gluing of partial silting sets

This paper focuses on recollements and silting theory in triangulated categories. It consists of two main parts. In the first part a criterion for a recollement of triangulated subcategories to lift to a torsion torsion-free triple (TTF triple) of ambient triangulated categories with coproducts is proved. As a consequence, lifting of TTF triples is possible for recollements of stable categories of repetitive algebras or self-injective finite length algebras and recollements of bounded derived categories of separated Noetherian schemes. When, in addition, the outer subcategories in the recollement are derived categories of small linear categories the conditions from the criterion are sufficient to lift the recollement to a recollement of ambient triangulated categories up to equivalence. In the second part we use these results to study the problem of constructing silting sets in the central category of a recollement generating the t-structure glued from the silting t-structures in the outer categories. In the case of a recollement of bounded derived categories of Artin algebras we provide an explicit construction for gluing classical silting objects.

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arXiv2020

Co-t-structures, cotilting and cotorsion pairs

Let $\mathsf{T}$ be a triangulated category with shift functor $Σ\colon \mathsf{T} \to \mathsf{T}$. Suppose $(\mathsf{A},\mathsf{B})$ is a co-t-structure with coheart $\mathsf{S} = Σ\mathsf{A} \cap \mathsf{B}$ and extended coheart $\mathsf{C} = Σ^2 \mathsf{A} \cap \mathsf{B} = \mathsf{S} * Σ\mathsf{S}$, which is an extriangulated category. We show that there is a bijection between co-t-structures $(\mathsf{A}',\mathsf{B}')$ in $\mathsf{T}$ such that $\mathsf{A} \subseteq \mathsf{A}' \subseteq Σ\mathsf{A}$ and complete cotorsion pairs in the extended coheart $\mathsf{C}$. In the case that $\mathsf{T}$ is Hom-finite, $\mathbf{k}$-linear and Krull-Schmidt, we show further that there is a bijection between complete cotorsion pairs in $\mathsf{C}$ and functorially finite torsion pairs in $\mathsf{mod}\, \mathsf{S}$.

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arXiv2018

Silting Theory in triangulated categories with coproducts

We introduce the notion of noncompact (partial) silting and (partial) tilting sets and objects in any triangulated category D with arbitrary (set-indexed) coproducts. We show that equivalence classes of partial silting sets are in bijection with t-structures generated by their co-heart whose heart has a generator, and in case D is compactly generated, this bijection restricts to one between equivalence classes of self-small partially silting objects and left nondegenerate t-structures in D whose heart is a module category and whose associated cohomological functor preserves products. We describe the objects in the aisle of the t-structure associated to a partial silting set T as the Milnor (aka homotopy) colimit of sequences of morphisms with succesive cones in Sum(T)[n]. We use this fact to develop a theory of tilting objects in very general AB3 abelian categories, a setting and its dual on which we show the validity of several well-known results of tilting and cotilting theory of modules. Finally, we show that if T is a bounded tilting set in a compactly generated algebraic triangulated category D and H is the heart of the associated t-structure, then the inclusion of H in D extends to a triangulated equivalence between the derived category D(H) of H and the ambient triangulated category D which restricts to bounded levels.

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arXiv2017

On stably biserial algebras and the Auslander-Reiten conjecture for special biserial algebras

By a result claimed by Pogorzały selfinjective special biserial algebras can be stably equivalent only to stably biserial algebras and these two classes coincide. By an example of Ariki, Iijima and Park the classes of stably biserial and selfinjective special biserial algebras do not coincide. In these notes we provide a detailed proof of the fact that a selfinjective special biserial algebra can be stably equivalent only to a stably biserial algebra following some ideas from the paper by Pogorzały. We will analyse the structure of symmetric stably biserial algebras and show that in characteristic $\neq 2$ the classes of symmetric special biserial (Brauer graph) algebras and symmetric stably biserial algebras indeed coincide. Also, we provide a proof of the Auslander-Reiten conjecture for special biserial algebras.

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arXiv2017

Contractibility of the stability manifold for silting-discrete algebras

We show that any bounded t-structure in the bounded derived category of a silting-discrete algebra is algebraic, i.e. has a length heart with finitely many simple objects. As a corollary, we obtain that the space of Bridgeland stability conditions for a silting-discrete algebra is contractible.

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arXiv2017

Külshammer ideals of graded categories and Hochschild cohomology

We generalize the notion of Külshammer ideals to the setting of a graded category. This allows us to define and study some properties of Külshammer type ideals in the graded center of a triangulated category and in the Hochschild cohomology of an algebra, providing new derived invariants. Further properties of Külshammer ideals are studied in the case where the category is $d$-Calabi-Yau.

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arXiv2015

Derived Picard groups of selfinjective Nakayama algebras

In our proceeding paper a generating set of the derived Picard group of a selfinjective Nakayama algebra was constructed combining some previous results for Brauer tree algebras and the technique of orbit categories developed there. In this paper we finish the computation of the derived Picard group of a selfinjective Nakayama algebra.

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arXiv2015

On the derived Picard group of the Brauer star algebra

In this paper we show that the derived Picard group $TrPic(A)$ of the Brauer star algebra of type $(n,t)$ is generated by shift, $Pic(A)$ and equivalences $\{H_i\}_{i=1}^n$ in the case $t>1$, where $H_i$ were shown to satisfy the relations of the braid group on the affine diagram $\widetilde{A}_{n-1}$ by Schaps and Zakay-Illouz. In the multiplicity free case we show that $TrPic(A)$ is generated by a slightly bigger set.

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arXiv2015

On standard derived equivalences of orbit categories

Let $\kk$ be a commutative ring, $\AAA$ and $\BB$ -- two $\kk$-linear categories with an action of a group $G$. We introduce the notion of a standard $G$-equivalence from $\Kb\BB$ to $\Kb\AAA$. We construct a map from the set of standard $G$-equivalences to the set of standard equivalences from $\Kb\BB$ to $\Kb\AAA$ and a map from the set of standard $G$-equivalences from $\Kb\BB$ to $\Kb\AAA$ to the set of standard equivalences from $\Kb(\BB/G)$ to $\Kb(\AAA/G)$. We investigate the properties of these maps and apply our results to the case where $\AAA=\BB=R$ is a Frobenius $\kk$-algebra and $G$ is the cyclic group generated by its Nakayama automorphism $ν$. We apply this technique to obtain the generating set of the derived Picard group of a Frobenius Nakayama algebra over an algebraically closed field.

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