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BEGIN:VEVENT
SUMMARY:Henning Krause (Bielefeld University)
DTSTART:20221012T113000Z
DTEND:20221012T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/1
DESCRIPTION:Title: Stratification of integral representations for finite groups
\nby Henning Krause (Bielefeld University) as part of RA Seminar\n\n\nAbst
ract\nWe consider representations of finite groups over a commutative noet
herian ring and explain a classification of thick and localising tensor id
eals via group cohomology. Some focus will be on the definition of the app
ropriate categories of representations such that the existing machinery ca
n be applied. Another crucial ingredient is the passage to the finite dime
nsional fibres for any group algebra. This is a report on joint work with
Dave Benson\, Srikanth Iyengar\, and Julia Pevtsova.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Bernhard Keller (Paris City University)
DTSTART:20221109T113000Z
DTEND:20221109T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/2
DESCRIPTION:Title: Hom-infinite Higgs categories\nby Bernhard Keller (Paris Cit
y University) as part of RA Seminar\n\n\nAbstract\nIn his thesis\, Yilin W
u has realized every Jacobi-finite ice quiver with potential as the ice qu
iver associated with a cluster-tilting object in the Higgs category\, a ce
rtain Frobenius extriangulated category which generalizes the category of
representations of a preprojective algebra. We will report on joint work w
ith Yilin Wu where we extend his results to a large class of Jacobi-infini
te ice quivers with potential.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Amnon Neeman (Australian National University)
DTSTART:20221214T113000Z
DTEND:20221214T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/3
DESCRIPTION:Title: Vanishing negative K-theory and bounded t-structures\nby Amn
on Neeman (Australian National University) as part of RA Seminar\n\n\nAbst
ract\nWe will begin with a quick reminder of algebraic K-theory\, and a fe
w classical\, vanishing results for negative K-theory. The talk will then
focus on a striking 2019 article by Antieau\, Gepner and Heller - it turns
out that there are K-theoretic obstructions to the existence of bounded t
-structures. The result suggests many questions. A few have already been a
nswered\, but many remain open. We will concentrate on the many possible d
irections for future research.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Volodymyr Mazorchuk (Uppsala University)
DTSTART:20230111T113000Z
DTEND:20230111T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/4
DESCRIPTION:Title: Homological invariants of category O\nby Volodymyr Mazorchuk
(Uppsala University) as part of RA Seminar\n\n\nAbstract\nThis will be a
survey talk about homological\nproperties of the Bernstein-Gelfand-Gelfand
\ncategory O associated with a triangular\ndecomposition of a semi-simple
complex\nfinite dimensional Lie algebra. Blocks of O\nare module categorie
s over finite dimensional\nassociative algebras having many nice propertie
s\nand symmetries\, inclduing quasi-heredity\,\nRingel self-duality\, Kosz
ul self-duality\,\nAuslander regularity etc. I will try to\npresent a numb
er of results describing\nhomological properties and invariants\nfor these
blocks and describe both methods\nand tools which are used to establish t
hese\nresults.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Karin Baur (University of Leeds)
DTSTART:20230208T113000Z
DTEND:20230208T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/5
DESCRIPTION:Title: Frieze patterns and cluster theory\nby Karin Baur (Universit
y of Leeds) as part of RA Seminar\n\n\nAbstract\nCluster categories and cl
uster algebras can be described via triangulations of surfaces or via Post
nikov diagrams. In type A\, such triangulations lead to frieze patterns or
SL_2-friezes in the sense of Conway and Coxeter. We explain how infinite
frieze patterns arise and discuss their growth behaviour. In particular\,
we show that tame module categories yield friezes with linear growth.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mike Prest (University of Manchester)
DTSTART:20230315T113000Z
DTEND:20230315T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/6
DESCRIPTION:Title: Definable categories\nby Mike Prest (University of Mancheste
r) as part of RA Seminar\n\n\nAbstract\nA definable subcategory of a modul
e category is one which is closed under direct products\, directed colimit
s and pure submodules. Many interesting categories of this kind arise in
homological algebra and representation theory. Definable categories have
a rich internal structure and the natural functors between them mirror exa
ct functors between associated small abelian categories. I will give a var
iety of examples and describe some of their features.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sophie Morier-Genoud (Université Reims Champagne Ardenne)
DTSTART:20230412T113000Z
DTEND:20230412T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/7
DESCRIPTION:Title: q-analogues of real numbers\nby Sophie Morier-Genoud (Univer
sité Reims Champagne Ardenne) as part of RA Seminar\n\n\nAbstract\nThe mo
st popular q-analogues of numbers are certainly the q-integers and the q-b
inomial coefficients of Gauss which both appear in various areas of mathem
atics and physics. Most classical sequences of integers often have interes
ting q-analogues. With Valentin Ovsienko we recently suggested a notion of
q-analogues for rational numbers. Our approach is based on combinatorial
properties and continued fraction expansions of the rationals. The definit
ion of q-rationals naturally extends the one of q-integers and leads to ra
tios of polynomials with positive integer coefficients. A surprising pheno
menon of stabilization allows us to define q-irrational numbers as formal
power series with integer coefficients. I will explain all the constructio
ns and give the main properties of these q-numbers. The subject can be dev
eloped in connections with various topics such as the enumerative combinat
orics\, cluster algebras\, homological algebra\, Burau representation\, Jo
nes polynomials... I will briefly discuss some of these connections.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yann Palu (LAMFA\, Université UPJV Amiens)
DTSTART:20230614T113000Z
DTEND:20230614T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/11
DESCRIPTION:Title: Mutation of maximal rigid objects in 0-Auslander extriangulated
categories\nby Yann Palu (LAMFA\, Université UPJV Amiens) as part of
RA Seminar\n\n\nAbstract\nWe introduce the notion of a 0-Auslander extria
ngulated categories in order to study mutations in representation theory.
Our aim in this talk is to show that many examples of known mutations can
be interpreted as mutations of maximal rigid objects in some 0-Auslander e
xtriangulated category: cluster tilting mutation\, two-term silting mutati
on\, mutation of maximal almost-rigid modules\, mutation of intermediate c
o-t-structures\, flips of dissections...\nThis is a collaboration with Mik
hail Gorsky and Hiroyuki Nakaoka.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Srikanth Iyengar (University of Utah)
DTSTART:20230712T130000Z
DTEND:20230712T140000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/12
DESCRIPTION:Title: Lattices over group algebras\nby Srikanth Iyengar (Universi
ty of Utah) as part of RA Seminar\n\n\nAbstract\nThis talk is based on an
ongoing collaboration with Barthel\, Benson\, Krause\, and Pevtsova\, conc
erning the representation theory of a finite group over an arbitrary noet
herian commutative ring. Our goal is to understand the structure of the st
able module categories of representations that arise in this context. In m
y talk I will focus mostly on the construction and basic properties of the
stable categories. This part of our story can\, and is\, developed in the
more general context of Frobenius algebras.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Karin Erdmann (Mathematical Institute\, University of Oxford)
DTSTART:20230913T113000Z
DTEND:20230913T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/13
DESCRIPTION:Title: Tame Symmetric Algebras\nby Karin Erdmann (Mathematical Ins
titute\, University of Oxford) as part of RA Seminar\n\n\nAbstract\nWe giv
e an overview of Hybrid Algebras which we introduced in joint work with An
drzej Skowro´nski. This is a large class of tame symmetric algebras\, whi
ch unifies weighted surface algebras and special biserial symmetric algebr
as and other algebras. We discuss homological properties of tame symmetric
algebras more generally\, in particular the graph structure of stable Aus
lander-Reiten components.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ralf Schiffler (University of Connecticut)
DTSTART:20231108T130000Z
DTEND:20231108T140000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/14
DESCRIPTION:Title: On Gorenstein algebras of finite Cohen-Macaulay type\nby Ra
lf Schiffler (University of Connecticut) as part of RA Seminar\n\n\nAbstra
ct\nThis is a report on joint work with Khrystyna Serhiyenko. We study the
(stable) category of Cohen-Macaulay modules over 2-Calabi-Yau tilted alge
bras\, a class of non-commutative algebras given by a quiver with potentia
l. We are particularly interested in the case where the CM category is fin
ite. We show the following.\n\n(a) For a particularly nice subclass\, whic
h we call dimer tree algebras\, the stable CM-category is a 2-cluster cate
gory of Dynkin type A.\n\n(d) Every dimer tree algebra gives rise to sever
al skew-group algebras\, and for each of these the stable CM-category is a
2-cluster category of Dynkin type D.\n\n(e) We have examples of Dynkin ty
pes E.\n\nThe dimer tree algebras are characterized by two conditions on t
he quiver. For one\, we want that every arrow lies in an oriented (chordle
ss) cycle\, and moreover\, the dual graph of the quiver is a tree. For dim
er tree algebras\, we obtain a combinatorial model for the CM category in
terms of 2-diagonals in a regular polygon. For the type D\, we have a simi
lar model on a punctured polygon.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hiroyuki Nakaoka (Nagoya University)
DTSTART:20231213T113000Z
DTEND:20231213T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/15
DESCRIPTION:Title: Localization of extriangulated categories\nby Hiroyuki Naka
oka (Nagoya University) as part of RA Seminar\n\n\nAbstract\nThis talk is
based on a joint work with Yasuaki Ogawa and Arashi Sakai.\nOur main theor
em shows that the localization of an extriangulated\ncategory by a class o
f morphisms satisfying some conditions can be\nequipped with a natural str
ucture of an extriangulated category in a\nuniversal way. This constructio
n unifies several localizations involving\nabelian/exact/triangulated cate
gories known in the literature\, the\nrelation with which is given via bir
esolving/percolating thick\nsubcategories.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Markus Reineke (RUHR Universitat Bochum)
DTSTART:20240110T113000Z
DTEND:20240110T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/16
DESCRIPTION:Title: Homological properties of universal quiver representations\
nby Markus Reineke (RUHR Universitat Bochum) as part of RA Seminar\n\n\nAb
stract\nFine moduli spaces of quiver representations carry universal repre
sentations in vector bundles. Under mild numerical conditions\, we prove t
hat these are partial tilting bundles\, and discuss applications to the ge
ometry of the moduli spaces. Joint recent work with P. Belmans\, A. Brecan
\, H. Franzen\, G. Petrella\, arXiv:2311.17003\, arXiv:2311.17004\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lidia Angeleri Hügel (University of Verona)
DTSTART:20240214T113000Z
DTEND:20240214T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/17
DESCRIPTION:Title: Torsion pairs via the Ziegler spectrum\nby Lidia Angeleri H
ügel (University of Verona) as part of RA Seminar\n\n\nAbstract\nThe tors
ion pairs in the category mod(A) of \nfinite dimensional modules over a fi
nite\ndimensional algebra A form a complete lattice tors(A) which encodes
essential information on\nA. Another important measure for the complexity
of the category mod(A) is given by the set\nbrick(A) of isomorphism classe
s of \nfinite dimensional bricks\, i.e. modules whose endomorphism\nring i
s a skew-field.\nA fundamental tool for studying tors(A) and brick(A) and
their interrelationship is provided by\nsilting theory. It was shown by Ad
achi\, Iyama and Reiten that the poset formed by the functorially\nfinite
torsion pairs is isomorphic to the poset of compact 2-term silting complex
es. Moreover\,\ncompact 2-term silting complexes can be represented by pai
rs (M\; P) formed by a $\\tau$-rigid module\nM and a projective module P.
The $\\tau$-rigid modules also provide a link to the collection of bricks:
a result by Demonet\, Iyama and Jasso establishes a bijection between the
indecomposable $\\tau$-rigid modules and the set of bricks B having the p
roperty that the smallest torsion class in mod(A) containing B is functori
ally \nfinite. The aim of my talk is to lift these finiteness conditions a
nd describe the whole lattice tors(A) and the entire collection brick(A) i
n terms of large silting theory. It is more convenient\, however\, to work
with the dual concept of a cosilting complex\, since we can then take adv
antage of the fact that cosilting complexes are pure-injective and work in
the Ziegler spectrum\, a topological space associated to A. We will see t
hat the lattice tors(A) is isomorphic to a lattice given by pairs (Z\; I)
where Z is a closed and rigid set in the Ziegler spectrum of Mod(A) and I
is a set of indecomposable injective modules. Furthermore\, we will presen
t a large counterpart to the brick-$\\tau$-rigid correspondence mentioned
above.\n\nThis is a report on joint work with Rosanna Laking and Francesco
Sentieri.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Pauksztello (Lancaster University)
DTSTART:20240313T113000Z
DTEND:20240313T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/18
DESCRIPTION:Title: Tilting\, reduction and mutation for simple-minded objects\
nby David Pauksztello (Lancaster University) as part of RA Seminar\n\n\nAb
stract\nModule categories have two important types of generators: projecti
ve modules and simple modules. Morita theory describes equivalences of mod
ule categories in terms of images of projective modules. Tilting theory is
the generalisation of Morita theory to derived categories describing equi
valences of derived categories in terms of tilting objects. Tilting\, silt
ing and cluster-tilting objects\, can be thought of as ‘projective-minde
d objects’. \n\n\n‘Simple-minded objects’ are generalisations of sim
ple modules. They satisfy Schur’s lemma and a version of the Jordan-Hold
er theorem\, depending on context. Although the theory of simple-minded ob
jects shows many parallels with that of projective-minded objects\, it rem
ains relatively undeveloped and is technically more challenging. It remain
s important to develop this theory because many natural classes of example
s\, for instance\, stable module categories\, have no projective-minded ob
jects but do have simple-minded objects. In this talk\, I will explain asp
ects of the theory of simple-minded objects\, including mutation and reduc
tion. I will explain how this gives a conceptual understanding of why tilt
ing algebraic hearts at torsion pairs generated by simple modules always y
ields an algebraic heart\, which has applications for spaces of stability
conditions. This talk will be based on various joint works with Nathan Bro
omhead\, Raquel Coelho Simoes\, David Ploog and Jon Woolf.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aslak Bakke Buan (Norwegian University of Science and Technology)
DTSTART:20240508T113000Z
DTEND:20240508T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/19
DESCRIPTION:Title: Mutation of $\\tau$-exceptional sequences\nby Aslak Bakke B
uan (Norwegian University of Science and Technology) as part of RA Seminar
\n\n\nAbstract\nWe first recall classical notions of exceptional sequences
and their mutations for module categories of hereditary algebras (e.g. pa
th algebras). Next\, we discuss a generalization to all finite dimensional
algebras\, motivated by $\\tau$-tilting theory\, by Adachi-Iyama-Reiten\;
by Jasso's reduction techniques for such modules and corresponding torsio
n pairs\; and by the introduction of signed exceptional sequences by Igusa
-Todorov.\nThe interplay between theories for $\\tau$-rigid modules\, tors
ion pairs and\nwide subcategories are central to our discussions.\nThis ta
lk is based on joint work with Eric Hanson and Bethany Marsh.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Thomas Brustle (Bishop's University and Université de Sherbrooke)
DTSTART:20240612T113000Z
DTEND:20240612T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/20
DESCRIPTION:Title: Homological algebra in persistence theory\nby Thomas Brustl
e (Bishop's University and Université de Sherbrooke) as part of RA Semina
r\n\n\nAbstract\nMultiparameter persistence modules appear in topological
data analysis when dealing with noisy data. They are defined over a wild p
oset algebra and therefore one cannot give a complete description of their
indecomposables. The aim of persistence theory is to roughly describe the
se modules by linear invariants\, i.e. additive functions which are consta
nt on isomorphism classes. We discuss several examples of such invariants
that can be obtained from order embeddings\, or by using relative homologi
cal algebra. \nThis is a report on joint work with Claire Amiot and Eric
Hanson. No prior knowledge of topological data analysis is required.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hugh Thomas (Université du Québec à Montréal)
DTSTART:20240710T123000Z
DTEND:20240710T133000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/21
DESCRIPTION:Title: Flow polytopes and gentle algebras\nby Hugh Thomas (Univers
ité du Québec à Montréal) as part of RA Seminar\n\n\nAbstract\nA recen
t paper by von Bell\, Braun\, Bruegge\, Hanely\, Peterson\, Serhiyenko and
Yip (arXiv:2203.01896) made an important connection between the tau-tilti
ng theory of (some) gentle algebras and the flow polytopes of (some) orien
ted graphs. We deepen the connection and relax the conditions on the orien
ted graphs. This is joint work with Abram\, Bastidas\, Brauner\, Dequêne\
, Morales\, and Park.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jan Stovicek (Charles University in Prague)
DTSTART:20240814T113000Z
DTEND:20240814T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/22
DESCRIPTION:Title: Semiorthogonal decompositions for bounded derived categories of
gentle algebras\nby Jan Stovicek (Charles University in Prague) as pa
rt of RA Seminar\n\n\nAbstract\nThe class of gentle algebras attracted a l
ot of attention in recent years. It is a relatively special class of algeb
ras\, yet appearing naturally in various contexts and serving as a good te
st class. In recent work with Jakub Kopřiva (arXiv:2209.14496)\, we study
semiorthogonal decompositions of bounded derived categories of gentle alg
ebras. It turns out that they have a very nice interpretation in terms of
a geometric model of bounded derived categories as constructed by Opper\,
Plamondon and Schroll (arXiv:1801.09659) - they simply correspond to suita
ble cuts of the marked surface underlying the geometric model. Moreover\,
both parts of such a semiorthogonal decomposition are again bounded derive
d categories of (graded) gentle algebras and their geometric models corres
pond to the parts of the surface. Our main tool is the characterization of
basis morphisms between indecomposable objects due to Arnesen\, Laking an
d Pauksztello.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yu Qiu (Yau Mathematical Sciences Center\, Tsinghua University)
DTSTART:20240911T113000Z
DTEND:20240911T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/23
DESCRIPTION:Title: Deformed 3-Calabi-Yau categories and partial compactifications
with orbifolding\nby Yu Qiu (Yau Mathematical Sciences Center\, Tsingh
ua University) as part of RA Seminar\n\n\nAbstract\nWe introduce a new fam
ily of quivers with potential for triangulated marked surfaces with punctu
res. We show that the deformation of the associated 3-Calabi-Yau categorie
s corresponds to the partial compactification (with orbifolding) of the as
sociated moduli spaces. As an application\, we calculate the fundamental g
roups of these moduli spaces (of framed quadratic differentials)\, which i
n particular produces Euclidean Artin braid groups of type A\, B\, C and D
.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sibylle Schroll (University of Cologne)
DTSTART:20241009T123000Z
DTEND:20241009T133000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/24
DESCRIPTION:by Sibylle Schroll (University of Cologne) as part of RA Semin
ar\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fan Qin (Beijing Normal University)
DTSTART:20241113T113000Z
DTEND:20241113T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/25
DESCRIPTION:Title: Analogs of dual canonical bases for cluster algebras from Lie t
heory\nby Fan Qin (Beijing Normal University) as part of RA Seminar\n\
n\nAbstract\nThe (quantized) coordinate rings of many interesting varietie
s from Lie theory are (quantum) cluster algebras. We construct the common
triangular bases for these algebras. Such bases provide analogs of the dua
l canonical bases\, whose existence has been long expected in cluster theo
ry. For symmetric Cartan matrices\, they are positive and admit monoidal c
ategorification after base change.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ivo Herzog (The Ohio State University)
DTSTART:20241211T113000Z
DTEND:20241211T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/26
DESCRIPTION:Title: The Generalized Generating Hypothesis\nby Ivo Herzog (The O
hio State University) as part of RA Seminar\n\n\nAbstract\nGhost morphisms
of various kinds will be unified under a notion of Ext-orthogonality for
maps\, which allows us to formulate a transfinite version of the generatin
g hypothesis. An ideal version of Eklof's Lemma\, together with the work o
f Enochs and Stovicek on bounds of filtrations\, establishes the Generaliz
ed Generating Hypothesis for certain ordinals. \n\nA corollary of the GGH
is that if the left pure projective modules over a ring R are closed under
extension\, then every FP-projective module is pure projective. This is t
he dual of a result by Xu which states that if the pure injective modules
are closed under extension\, then every cotorsion module is pure injective
. This talk is based on joint work with Sergio Estrada\, Xianhui Fu and Si
nem Odabasi.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Claire Amiot (University of Grenoble Alpes)
DTSTART:20250108T113000Z
DTEND:20250108T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/27
DESCRIPTION:Title: Tilting objects for gentle and skew-gentle algebras using the g
eometric model.\nby Claire Amiot (University of Grenoble Alpes) as par
t of RA Seminar\n\n\nAbstract\nGentle algebras have been introduced in the
80’s by Assem and Skwronski. This class of algebras have been recently
linked with graded surfaces via the work of Haiden Katzarkov and Kontsevic
h and Opper\, Plamondon and Schroll. In this talk I will explain how to de
tect tilting objects for gentle algebras using this geometric model. This
is a joint work with Plamondon and Schroll. If time permits\, I will expla
in how to generalize these results for skew-gentle algebras. This is a col
laboration with Plamondon.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniel Labardini Fragoso (University of Padova)
DTSTART:20250212T113000Z
DTEND:20250212T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/28
DESCRIPTION:Title: Mutations of infinite-dimensional representations\nby Danie
l Labardini Fragoso (University of Padova) as part of RA Seminar\n\n\nAbst
ract\nI will report on an ongoing joint project with Rosie Laking and Lang
Mou devoted to extending Derksen-Weyman-Zelevinsky's mutations of represe
ntations of quivers with potential from the finite-dimensional setting to
the possibly infinite-dimensional one and establishing the good mutation b
ehavior of several classes of infinite-dimensional representations.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andrea Solotar (University of Buenos Aires)
DTSTART:20250312T113000Z
DTEND:20250312T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/29
DESCRIPTION:by Andrea Solotar (University of Buenos Aires) as part of RA S
eminar\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jeremy Rickard (University of Bristol)
DTSTART:20250409T113000Z
DTEND:20250409T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/30
DESCRIPTION:Title: Are finiteness conditions derived invariant?\nby Jeremy Ric
kard (University of Bristol) as part of RA Seminar\n\n\nAbstract\nTwo ring
s are "Morita equivalent" if they have equivalent module categories\, and\
nif a property of rings depends only on the module category\, then it is c
alled\n"Morita invariant". More generally\, two rings are "derived equival
ent" if they\nhave equivalent derived categories\, and if a property of ri
ngs depends only on\nthe derived category\, then it is called "derived inv
ariant".\n\nFairly recently\, Manuel Saorin asked me if I knew whether rig
ht coherence was a\nderived invariant property. I didn't\, but when my lon
g term memory kicked in\, I\nrealised that an example hidden in my 36 year
old PhD thesis could be used to\ngive a counterexample.\n\nMost of the ta
lk will be an introduction to the background to this question and\nvariant
s\, but it will finish with some fun examples of rings with strange\nprope
rties.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rosanna Laking (Università degli Studi di Verona)
DTSTART:20250514T113000Z
DTEND:20250514T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/31
DESCRIPTION:Title: Wide intervals and closed rigid sets\nby Rosanna Laking (Un
iversità degli Studi di Verona) as part of RA Seminar\n\n\nAbstract\nAn o
ld result of Ringel states that semibricks (i.e.\, sets of pairwise Hom-or
thogonal bricks) in the category modA of finite-dimensional modules over a
finite-dimensional algebra are in bijection with the wide subcategories o
f modA (i.e. subcategories that are closed under kernels\, cokernels and e
xtensions). These subcategories are interesting abelian length subcategor
ies of modA that arise naturally in various contexts throughout the repres
entation theory of A.\n\nIn this talk we will be focusing on one such cont
ext: when non-trivial wide subcategories arise as intersections of a torsi
on class T and a torsion-free class V in modA. Such a pair T and V corres
ponds to an interval in the lattice of torsion pairs in modA that Asai and
Pfeifer call wide intervals. We will report on joint work with Lidia Ang
eleri Hügel and Francesco Sentieri in which we show that wide intervals a
re parametrised by certain closed sets of the Ziegler spectrum of the unbo
unded derived module category of A.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pu Zhang (Shanghai Jiao Tong University)
DTSTART:20250709T113000Z
DTEND:20250709T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/32
DESCRIPTION:Title: Homological dimension and model structures\nby Pu Zhang (Sh
anghai Jiao Tong University) as part of RA Seminar\n\n\nAbstract\nFor any
integer n ≥ 0 and any ring R\, $(PGF_n \,P_n^⊥∩ PGF^⊥)$ proves to
be a complete hereditary cotorsion pair in R-Mod\, where $PGF$ is the cla
ss of $PGF$ modules\, introduced by J.Šaroch and J. Št́ovíček\, and $
PGF_n$ is the class of R-modules of PGF dimension ≤ n. For any Artin alg
ebra R\, $(GP_n\, P_n^⊥∩ GP^⊥)$ proves to be a complete and heredita
ry cotorsion pair in R-Mod\, where $GP_n$ is the class of modules of Goren
stein projective dimension ≤ n. These cotorsion pairs induce two chains
of hereditary Hovey triples $(PGF_n\,P_n^⊥ \,PGF^⊥)$ and $(GP_n\, P_n
^⊥\, GP^⊥)$\, and the corresponding homotopy categories in the same ch
ain are the same. It is observed that some complete cotorsion pairs in R-M
od can induce complete cotorsion pairs in some special extension closed su
bcategories of R-Mod. Then corresponding results in exact categories $PGF_
n\, GP_n\, GF_n\,PGF^{<∞}\,GP^{<∞}$ and $GF^{<∞}$\, are also obtaine
d. As a byproduct\, $PGF= GP$ for a ring R if and only if $PGF^⊥ ∩ GP
_n= P_n$ for some $n$.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gustavo Jasso (University of Cologne)
DTSTART:20250910T113000Z
DTEND:20250910T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/33
DESCRIPTION:Title: The Calabi-Yau Auslander-Iyama Correspondence\nby Gustavo J
asso (University of Cologne) as part of RA Seminar\n\n\nAbstract\nThis tal
k reports on joint work with Fernando Muro (Sevilla).\nLet d be a positive
integer. In previous work we established\na bijective correspondence betw
een the following classes of objects\,\nconsidered up to the appropriate n
otion of equivalence: differential\ngraded algebras with finite-dimensiona
l 0-th cohomology such that the\ncanonical generator of their perfect deri
ved category is a basic\ndZ-cluster tilting object\, and basic Frobenius a
lgebras that are twisted\n(d+2)-periodic as bimodules. For d=1 this corres
pondence specialises to\nprevious work of the second-named author on algeb
raic triangulated\ncategories of finite type. In this talk\, I will explai
n a variant of our\ngeneral correspondence for bimodule right Calabi–Yau
dg algebras. A\nnovel ingredient is a new cohomology theory that we call
bimodule\nHochschild–Massey cohomology and which contains obstructions t
o the\nexistence and uniqueness of minimal A∞-bimodule structures on a g
raded\nbimodule.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Khrystyna Serhiyenko (University of Kentucky)
DTSTART:20250611T113000Z
DTEND:20250611T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/34
DESCRIPTION:Title: Classical tilting and tau-tilting theory\nby Khrystyna Serh
iyenko (University of Kentucky) as part of RA Seminar\n\n\nAbstract\nTau-t
ilting theory can be thought of as a generalization of the classical tilti
ng theory\, which allows mutations at any indecomposable summand of a supp
ort tau-tilting module. Indeed\, tilting modules are tau-tilting modules
and they form a subposet of the support tau-tilting poset. Conversely\,
we show that the tau-tilting theory of an algebra can be naturally identif
ied with the classical tilting theory of its duplicated algebra. This ext
ends the results of Assem-Brüstle-Schiffler-Todorov in the case of heredi
tary algebras.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/34/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sondre Kvamme (Norwegian University of Science and Technology)
DTSTART:20250813T113000Z
DTEND:20250813T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/35
DESCRIPTION:Title: The reconstruction problem for d-cluster tilting subcategories
of exact categories\nby Sondre Kvamme (Norwegian University of Science
and Technology) as part of RA Seminar\n\n\nAbstract\nWe explain how any w
eakly idempotent complete d-exact category is equivalent to a d-cluster ti
lting subcategory of a weakly idempotent complete exact category\, and tha
t the exact category must be unique up to exact equivalence. We explain ho
w this gives an answer to the reconstruction problem for d-cluster tilting
subcategories of exact categories.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/35/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yuya Mizuno (Osaka Metropolitan University)
DTSTART:20251112T113000Z
DTEND:20251112T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/36
DESCRIPTION:Title: On the d-polynomial for preprojective algebras\nby Yuya Miz
uno (Osaka Metropolitan University) as part of RA Seminar\n\n\nAbstract\nI
n recent years\, $\\tau$-tilting theory and its related theories have been
the subject of very active research. In this talk\, we will introduce a n
ew concept\, the "d-polynomial\," which is determined from $\\tau$-rigid m
odules\, and discuss its properties. \nIn short\, this polynomial represen
ts an enumeration of the dimensions of $\\tau$-rigid modules and can be re
garded as a measure of homological quantities. I will particularly focus o
n the preprojective algebra of type A\, and explain the close relationship
between the d-polynomial and the Eulerian polynomial in that case. This i
s based on joint work with Toshitaka Aoki.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/36/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Charles Paquette (Royal Military College of Canada)
DTSTART:20251008T113000Z
DTEND:20251008T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/37
DESCRIPTION:Title: Brick-directed torsion classes and the notion of brick-splittin
g\nby Charles Paquette (Royal Military College of Canada) as part of R
A Seminar\n\n\nAbstract\nBricks are playing a fundamental role in modern r
epresentation theory of algebras. Based on the successful use of represent
ation-directed algebras in classification problems\, we introduce the bric
k-analogue version which is that of brick-directed algebra. We show that b
rick-directed algebras can be characterized by many different algebraic an
d geometric aspects of the algebra. In particular\, we show that a brick-f
inite algebra A is brick-directed if and only if its lattice of torsion cl
asses is modular (equivalently\, extremal). This is based on joint work wi
th Sota Asai\, Kaveh Mousavand and Osamu Iyama.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/37/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eleonore Faber (University of Graz)
DTSTART:20251210T113000Z
DTEND:20251210T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/38
DESCRIPTION:Title: From additive friezes to associahedra\nby Eleonore Faber (U
niversity of Graz) as part of RA Seminar\n\n\nAbstract\nFrieze patterns of
integers were first studied by Coxeter and Conway-Coxeter in the 1970s fr
om a combinatorial perspective. Since the 2000s they had a remarkable rena
issance in cluster theory\, in particular\, in connection with cluster cat
egories of type A.\nIn this talk\, we consider the variant of nonnegative
additive frieze patterns. Our goal is to find a representation theoretic i
nterpretation of these friezes through a root category as well as a way to
enumerate them. Therefore we consider associahedra coming from the cluste
r category\, which lead us to a construction of an associahedron for our r
oot category.\nThis is joint work with Asilata Bapat\, Véronique Bazier-M
atte\, Kunda Kambaso\, Bethany Marsh\, and Yadira Valdivieso.\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/38/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nicholas Williams (University of Cambridge)
DTSTART:20260114T113000Z
DTEND:20260114T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/39
DESCRIPTION:Title: The talk has been postponed to 8 April.\nby Nicholas Willia
ms (University of Cambridge) as part of RA Seminar\n\n\nAbstract\nA well-k
nown result of Fomin and Zelevinsky states that clusters in the type A clu
ster algebra are in bijection with triangulations of a convex polygon. In
previous work\, I showed a three-dimensional version of this bijection\, n
amely that equivalence classes of maximal green sequences of linearly orie
nted type A are in bijection with triangulations of a three-dimensional cy
clic polytope. It is natural to wonder whether there exist analogous resul
ts for other orientations of the type A Dynkin diagram. Namely\, given suc
h an orientation\, is there a polytope whose triangulations correspond to
equivalence classes of maximal green sequences? In this talk I will explai
n recent work which goes some way towards asking this question. Namely\, I
show that\, given a cluster-tilting object T in the type A cluster catego
ry\, there is an oriented matroid whose stackable triangulations correspon
d to equivalence classes of maximal green sequences of End(T).\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/39/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jorge Vitoria (University of Padova)
DTSTART:20260211T113000Z
DTEND:20260211T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/40
DESCRIPTION:Title: The talk has been postponed to 13 May.\nby Jorge Vitoria (U
niversity of Padova) as part of RA Seminar\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/40/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rene Marczinzic (University of Bonn)
DTSTART:20260311T113000Z
DTEND:20260311T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/41
DESCRIPTION:by Rene Marczinzic (University of Bonn) as part of RA Seminar\
n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/41/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nicholas Williams (University of Cambridge)
DTSTART:20260408T113000Z
DTEND:20260408T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/42
DESCRIPTION:Title: Oriented matroids and maximal green sequences of type A cluster
algebras\nby Nicholas Williams (University of Cambridge) as part of R
A Seminar\n\n\nAbstract\nA well-known result of Fomin and Zelevinsky state
s that clusters in the type A cluster algebra are in bijection with triang
ulations of a convex polygon. In previous work\, I showed a three-dimensio
nal version of this bijection\, namely that equivalence classes of maximal
green sequences of linearly oriented type A are in bijection with triangu
lations of a three-dimensional cyclic polytope. It is natural to wonder wh
ether there exist analogous results for other orientations of the type A D
ynkin diagram. Namely\, given such an orientation\, is there a polytope wh
ose triangulations correspond to equivalence classes of maximal green sequ
ences? In this talk I will explain recent work which goes some way towards
asking this question. Namely\, I show that\, given a cluster-tilting obje
ct T in the type A cluster category\, there is an oriented matroid whose s
tackable triangulations correspond to equivalence classes of maximal green
sequences of End(T).\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/42/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jorge Vitoria (University of Padova)
DTSTART:20260513T113000Z
DTEND:20260513T123000Z
DTSTAMP:20260404T025028Z
UID:RA-Seminar/43
DESCRIPTION:by Jorge Vitoria (University of Padova) as part of RA Seminar\
n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/RA-Seminar/43/
END:VEVENT
END:VCALENDAR