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BEGIN:VEVENT
SUMMARY:Henning Krause (Bielefeld University)
DTSTART:20221012T113000Z
DTEND:20221012T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/1
DESCRIPTION:Title: Stratification of integral representations for finite groups\nby He
nning Krause (Bielefeld University) as part of RA Seminar\n\n\nAbstract\nW
e consider representations of finite groups over a commutative noetherian
ring and explain a classification of thick and localising tensor ideals vi
a group cohomology. Some focus will be on the definition of the appropriat
e categories of representations such that the existing machinery can be ap
plied. Another crucial ingredient is the passage to the finite dimensional
fibres for any group algebra. This is a report on joint work with Dave Be
nson\, Srikanth Iyengar\, and Julia Pevtsova.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Bernhard Keller (Paris City University)
DTSTART:20221109T113000Z
DTEND:20221109T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/2
DESCRIPTION:Title: Hom-infinite Higgs categories\nby Bernhard Keller (Paris City Unive
rsity) as part of RA Seminar\n\n\nAbstract\nIn his thesis\, Yilin Wu has r
ealized every Jacobi-finite ice quiver with potential as the ice quiver as
sociated with a cluster-tilting object in the Higgs category\, a certain F
robenius extriangulated category which generalizes the category of represe
ntations of a preprojective algebra. We will report on joint work with Yil
in Wu where we extend his results to a large class of Jacobi-infinite ice
quivers with potential.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Amnon Neeman (Australian National University)
DTSTART:20221214T113000Z
DTEND:20221214T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/3
DESCRIPTION:Title: Vanishing negative K-theory and bounded t-structures\nby Amnon Neem
an (Australian National University) as part of RA Seminar\n\n\nAbstract\nW
e will begin with a quick reminder of algebraic K-theory\, and a few class
ical\, vanishing results for negative K-theory. The talk will then focus o
n a striking 2019 article by Antieau\, Gepner and Heller - it turns out th
at there are K-theoretic obstructions to the existence of bounded t-struct
ures. The result suggests many questions. A few have already been answered
\, but many remain open. We will concentrate on the many possible directio
ns for future research.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Volodymyr Mazorchuk (Uppsala University)
DTSTART:20230111T113000Z
DTEND:20230111T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/4
DESCRIPTION:Title: Homological invariants of category O\nby Volodymyr Mazorchuk (Uppsa
la University) as part of RA Seminar\n\n\nAbstract\nThis will be a survey
talk about homological\nproperties of the Bernstein-Gelfand-Gelfand\ncateg
ory O associated with a triangular\ndecomposition of a semi-simple complex
\nfinite dimensional Lie algebra. Blocks of O\nare module categories over
finite dimensional\nassociative algebras having many nice properties\nand
symmetries\, inclduing quasi-heredity\,\nRingel self-duality\, Koszul self
-duality\,\nAuslander regularity etc. I will try to\npresent a number of r
esults describing\nhomological properties and invariants\nfor these blocks
and describe both methods\nand tools which are used to establish these\nr
esults.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Karin Baur (University of Leeds)
DTSTART:20230208T113000Z
DTEND:20230208T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/5
DESCRIPTION:Title: Frieze patterns and cluster theory\nby Karin Baur (University of Le
eds) as part of RA Seminar\n\n\nAbstract\nCluster categories and cluster a
lgebras can be described via triangulations of surfaces or via Postnikov d
iagrams. In type A\, such triangulations lead to frieze patterns or SL_2-f
riezes 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://researchseminars.org/talk/RA-Seminar/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mike Prest (University of Manchester)
DTSTART:20230315T113000Z
DTEND:20230315T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/6
DESCRIPTION:Title: Definable categories\nby Mike Prest (University of Manchester) as p
art of RA Seminar\n\n\nAbstract\nA definable subcategory of a module categ
ory is one which is closed under direct products\, directed colimits and p
ure submodules. Many interesting categories of this kind arise in homolog
ical algebra and representation theory. Definable categories have a rich
internal structure and the natural functors between them mirror exact func
tors between associated small abelian categories. I will give a variety of
examples and describe some of their features.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sophie Morier-Genoud (Université Reims Champagne Ardenne)
DTSTART:20230412T113000Z
DTEND:20230412T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/7
DESCRIPTION:Title: q-analogues of real numbers\nby Sophie Morier-Genoud (Université R
eims Champagne Ardenne) as part of RA Seminar\n\n\nAbstract\nThe most popu
lar q-analogues of numbers are certainly the q-integers and the q-binomial
coefficients of Gauss which both appear in various areas of mathematics a
nd physics. Most classical sequences of integers often have interesting q-
analogues. With Valentin Ovsienko we recently suggested a notion of q-anal
ogues for rational numbers. Our approach is based on combinatorial propert
ies and continued fraction expansions of the rationals. The definition of
q-rationals naturally extends the one of q-integers and leads to ratios of
polynomials with positive integer coefficients. A surprising phenomenon o
f stabilization allows us to define q-irrational numbers as formal power s
eries with integer coefficients. I will explain all the constructions and
give the main properties of these q-numbers. The subject can be developed
in connections with various topics such as the enumerative combinatorics\,
cluster algebras\, homological algebra\, Burau representation\, Jones pol
ynomials... I will briefly discuss some of these connections.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yann Palu (LAMFA\, Université UPJV Amiens)
DTSTART:20230614T113000Z
DTEND:20230614T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/11
DESCRIPTION:Title: Mutation of maximal rigid objects in 0-Auslander extriangulated catego
ries\nby Yann Palu (LAMFA\, Université UPJV Amiens) as part of RA Sem
inar\n\n\nAbstract\nWe introduce the notion of a 0-Auslander extriangulate
d 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 inte
rpreted as mutations of maximal rigid objects in some 0-Auslander extriang
ulated category: cluster tilting mutation\, two-term silting mutation\, mu
tation of maximal almost-rigid modules\, mutation of intermediate co-t-str
uctures\, flips of dissections...\nThis is a collaboration with Mikhail Go
rsky and Hiroyuki Nakaoka.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Srikanth Iyengar (University of Utah)
DTSTART:20230712T130000Z
DTEND:20230712T140000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/12
DESCRIPTION:Title: Lattices over group algebras\nby Srikanth Iyengar (University of U
tah) as part of RA Seminar\n\n\nAbstract\nThis talk is based on an ongoing
collaboration with Barthel\, Benson\, Krause\, and Pevtsova\, concerning
the representation theory of a finite group over an arbitrary noetherian
commutative ring. Our goal is to understand the structure of the stable mo
dule categories of representations that arise in this context. In my 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 g
eneral context of Frobenius algebras.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Karin Erdmann (Mathematical Institute\, University of Oxford)
DTSTART:20230913T113000Z
DTEND:20230913T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/13
DESCRIPTION:Title: Tame Symmetric Algebras\nby Karin Erdmann (Mathematical Institute\
, University of Oxford) as part of RA Seminar\n\n\nAbstract\nWe give an ov
erview of Hybrid Algebras which we introduced in joint work with Andrzej S
kowro´nski. This is a large class of tame symmetric algebras\, which unif
ies weighted surface algebras and special biserial symmetric algebras and
other algebras. We discuss homological properties of tame symmetric algebr
as more generally\, in particular the graph structure of stable Auslander-
Reiten components.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ralf Schiffler (University of Connecticut)
DTSTART:20231108T130000Z
DTEND:20231108T140000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/14
DESCRIPTION:Title: On Gorenstein algebras of finite Cohen-Macaulay type\nby Ralf Schi
ffler (University of Connecticut) as part of RA Seminar\n\n\nAbstract\nThi
s is a report on joint work with Khrystyna Serhiyenko. We study the (stabl
e) category of Cohen-Macaulay modules over 2-Calabi-Yau tilted algebras\,
a class of non-commutative algebras given by a quiver with potential. We a
re particularly interested in the case where the CM category is finite. We
show the following.\n\n(a) For a particularly nice subclass\, which we ca
ll dimer tree algebras\, the stable CM-category is a 2-cluster category of
Dynkin type A.\n\n(d) Every dimer tree algebra gives rise to several skew
-group algebras\, and for each of these the stable CM-category is a 2-clus
ter category of Dynkin type D.\n\n(e) We have examples of Dynkin types E.\
n\nThe dimer tree algebras are characterized by two conditions on the quiv
er. For one\, we want that every arrow lies in an oriented (chordless) cyc
le\, and moreover\, the dual graph of the quiver is a tree. For dimer tree
algebras\, we obtain a combinatorial model for the CM category in terms o
f 2-diagonals in a regular polygon. For the type D\, we have a similar mod
el on a punctured polygon.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hiroyuki Nakaoka (Nagoya University)
DTSTART:20231213T113000Z
DTEND:20231213T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/15
DESCRIPTION:Title: Localization of extriangulated categories\nby Hiroyuki Nakaoka (Na
goya University) as part of RA Seminar\n\n\nAbstract\nThis talk is based o
n a joint work with Yasuaki Ogawa and Arashi Sakai.\nOur main theorem show
s that the localization of an extriangulated\ncategory by a class of morph
isms satisfying some conditions can be\nequipped with a natural structure
of an extriangulated category in a\nuniversal way. This construction unifi
es several localizations involving\nabelian/exact/triangulated categories
known in the literature\, the\nrelation with which is given via biresolvin
g/percolating thick\nsubcategories.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Markus Reineke (RUHR Universitat Bochum)
DTSTART:20240110T113000Z
DTEND:20240110T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/16
DESCRIPTION:Title: Homological properties of universal quiver representations\nby Mar
kus Reineke (RUHR Universitat Bochum) as part of RA Seminar\n\n\nAbstract\
nFine moduli spaces of quiver representations carry universal representati
ons in vector bundles. Under mild numerical conditions\, we prove that the
se are partial tilting bundles\, and discuss applications to the geometry
of the moduli spaces. Joint recent work with P. Belmans\, A. Brecan\, H. F
ranzen\, G. Petrella\, arXiv:2311.17003\, arXiv:2311.17004\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lidia Angeleri Hügel (University of Verona)
DTSTART:20240214T113000Z
DTEND:20240214T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/17
DESCRIPTION:Title: Torsion pairs via the Ziegler spectrum\nby Lidia Angeleri Hügel (
University of Verona) as part of RA Seminar\n\n\nAbstract\nThe torsion pai
rs in the category mod(A) of \nfinite dimensional modules over a finite\nd
imensional algebra A form a complete lattice tors(A) which encodes essenti
al information on\nA. Another important measure for the complexity of the
category mod(A) is given by the set\nbrick(A) of isomorphism classes of \n
finite dimensional bricks\, i.e. modules whose endomorphism\nring is a ske
w-field.\nA fundamental tool for studying tors(A) and brick(A) and their i
nterrelationship is provided by\nsilting theory. It was shown by Adachi\,
Iyama and Reiten that the poset formed by the functorially\nfinite torsion
pairs is isomorphic to the poset of compact 2-term silting complexes. Mor
eover\,\ncompact 2-term silting complexes can be represented by pairs (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 resu
lt by Demonet\, Iyama and Jasso establishes a bijection between the indeco
mposable $\\tau$-rigid modules and the set of bricks B having the property
that the smallest torsion class in mod(A) containing B is functorially \n
finite. The aim of my talk is to lift these finiteness conditions and desc
ribe the whole lattice tors(A) and the entire collection brick(A) in terms
of large silting theory. It is more convenient\, however\, to work with t
he dual concept of a cosilting complex\, since we can then take advantage
of the fact that cosilting complexes are pure-injective and work in the Zi
egler spectrum\, a topological space associated to A. We will see that 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 se
t of indecomposable injective modules. Furthermore\, we will present a lar
ge counterpart to the brick-$\\tau$-rigid correspondence mentioned above.\
n\nThis is a report on joint work with Rosanna Laking and Francesco Sentie
ri.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Pauksztello (Lancaster University)
DTSTART:20240313T113000Z
DTEND:20240313T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/18
DESCRIPTION:Title: Tilting\, reduction and mutation for simple-minded objects\nby Dav
id Pauksztello (Lancaster University) as part of RA Seminar\n\n\nAbstract\
nModule categories have two important types of generators: projective modu
les and simple modules. Morita theory describes equivalences of module cat
egories in terms of images of projective modules. Tilting theory is the ge
neralisation of Morita theory to derived categories describing equivalence
s of derived categories in terms of tilting objects. Tilting\, silting and
cluster-tilting objects\, can be thought of as ‘projective-minded objec
ts’. \n\n\n‘Simple-minded objects’ are generalisations of simple mod
ules. They satisfy Schur’s lemma and a version of the Jordan-Holder theo
rem\, depending on context. Although the theory of simple-minded objects s
hows many parallels with that of projective-minded objects\, it remains re
latively undeveloped and is technically more challenging. It remains impor
tant to develop this theory because many natural classes of examples\, for
instance\, stable module categories\, have no projective-minded objects b
ut do have simple-minded objects. In this talk\, I will explain aspects of
the theory of simple-minded objects\, including mutation and reduction. I
will explain how this gives a conceptual understanding of why tilting alg
ebraic hearts at torsion pairs generated by simple modules always yields a
n algebraic heart\, which has applications for spaces of stability conditi
ons. This talk will be based on various joint works with Nathan Broomhead\
, Raquel Coelho Simoes\, David Ploog and Jon Woolf.\n
LOCATION:https://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:20260315T023108Z
UID:RA-Seminar/19
DESCRIPTION:Title: Mutation of $\\tau$-exceptional sequences\nby Aslak Bakke Buan (No
rwegian University of Science and Technology) as part of RA Seminar\n\n\nA
bstract\nWe first recall classical notions of exceptional sequences and th
eir mutations for module categories of hereditary algebras (e.g. path alge
bras). Next\, we discuss a generalization to all finite dimensional algebr
as\, motivated by $\\tau$-tilting theory\, by Adachi-Iyama-Reiten\; by Jas
so's reduction techniques for such modules and corresponding torsion pairs
\; and by the introduction of signed exceptional sequences by Igusa-Todoro
v.\nThe interplay between theories for $\\tau$-rigid modules\, torsion pai
rs and\nwide subcategories are central to our discussions.\nThis talk is b
ased on joint work with Eric Hanson and Bethany Marsh.\n
LOCATION:https://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:20260315T023108Z
UID:RA-Seminar/20
DESCRIPTION:Title: Homological algebra in persistence theory\nby Thomas Brustle (Bish
op's University and Université de Sherbrooke) as part of RA Seminar\n\n\n
Abstract\nMultiparameter persistence modules appear in topological data an
alysis when dealing with noisy data. They are defined over a wild poset al
gebra and therefore one cannot give a complete description of their indeco
mposables. The aim of persistence theory is to roughly describe these modu
les by linear invariants\, i.e. additive functions which are constant on i
somorphism classes. We discuss several examples of such invariants that ca
n be obtained from order embeddings\, or by using relative homological al
gebra. \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://researchseminars.org/talk/RA-Seminar/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hugh Thomas (Université du Québec à Montréal)
DTSTART:20240710T123000Z
DTEND:20240710T133000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/21
DESCRIPTION:Title: Flow polytopes and gentle algebras\nby Hugh Thomas (Université du
Québec à Montréal) as part of RA Seminar\n\n\nAbstract\nA recent paper
by von Bell\, Braun\, Bruegge\, Hanely\, Peterson\, Serhiyenko and Yip (a
rXiv:2203.01896) made an important connection between the tau-tilting theo
ry of (some) gentle algebras and the flow polytopes of (some) oriented gra
phs. We deepen the connection and relax the conditions on the oriented gra
phs. This is joint work with Abram\, Bastidas\, Brauner\, Dequêne\, Moral
es\, and Park.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jan Stovicek (Charles University in Prague)
DTSTART:20240814T113000Z
DTEND:20240814T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/22
DESCRIPTION:Title: Semiorthogonal decompositions for bounded derived categories of gentle
algebras\nby Jan Stovicek (Charles University in Prague) as part of R
A Seminar\n\n\nAbstract\nThe class of gentle algebras attracted a lot of a
ttention in recent years. It is a relatively special class of algebras\, y
et appearing naturally in various contexts and serving as a good test clas
s. In recent work with Jakub Kopřiva (arXiv:2209.14496)\, we study semior
thogonal decompositions of bounded derived categories of gentle algebras.
It turns out that they have a very nice interpretation in terms of a geome
tric model of bounded derived categories as constructed by Opper\, Plamond
on and Schroll (arXiv:1801.09659) - they simply correspond to suitable cut
s of the marked surface underlying the geometric model. Moreover\, both pa
rts of such a semiorthogonal decomposition are again bounded derived categ
ories of (graded) gentle algebras and their geometric models correspond to
the parts of the surface. Our main tool is the characterization of basis
morphisms between indecomposable objects due to Arnesen\, Laking and Pauks
ztello.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yu Qiu (Yau Mathematical Sciences Center\, Tsinghua University)
DTSTART:20240911T113000Z
DTEND:20240911T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/23
DESCRIPTION:Title: Deformed 3-Calabi-Yau categories and partial compactifications with or
bifolding\nby Yu Qiu (Yau Mathematical Sciences Center\, Tsinghua Univ
ersity) as part of RA Seminar\n\n\nAbstract\nWe introduce a new family of
quivers with potential for triangulated marked surfaces with punctures. We
show that the deformation of the associated 3-Calabi-Yau categories corre
sponds to the partial compactification (with orbifolding) of the associate
d moduli spaces. As an application\, we calculate the fundamental groups o
f these moduli spaces (of framed quadratic differentials)\, which in parti
cular produces Euclidean Artin braid groups of type A\, B\, C and D.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sibylle Schroll (University of Cologne)
DTSTART:20241009T123000Z
DTEND:20241009T133000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/24
DESCRIPTION:by Sibylle Schroll (University of Cologne) as part of RA Semin
ar\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fan Qin (Beijing Normal University)
DTSTART:20241113T113000Z
DTEND:20241113T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/25
DESCRIPTION:Title: Analogs of dual canonical bases for cluster algebras from Lie theory\nby Fan Qin (Beijing Normal University) as part of RA Seminar\n\n\nAbst
ract\nThe (quantized) coordinate rings of many interesting varieties from
Lie theory are (quantum) cluster algebras. We construct the common triangu
lar bases for these algebras. Such bases provide analogs of the dual canon
ical bases\, whose existence has been long expected in cluster theory. For
symmetric Cartan matrices\, they are positive and admit monoidal categori
fication after base change.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ivo Herzog (The Ohio State University)
DTSTART:20241211T113000Z
DTEND:20241211T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/26
DESCRIPTION:Title: The Generalized Generating Hypothesis\nby Ivo Herzog (The Ohio Sta
te University) as part of RA Seminar\n\n\nAbstract\nGhost morphisms of var
ious kinds will be unified under a notion of Ext-orthogonality for maps\,
which allows us to formulate a transfinite version of the generating hypot
hesis. An ideal version of Eklof's Lemma\, together with the work of Enoch
s and Stovicek on bounds of filtrations\, establishes the Generalized Gene
rating 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 extens
ion\, then every FP-projective module is pure projective. This is the dual
of a result by Xu which states that if the pure injective modules are clo
sed under extension\, then every cotorsion module is pure injective. This
talk is based on joint work with Sergio Estrada\, Xianhui Fu and Sinem Oda
basi.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Claire Amiot (University of Grenoble Alpes)
DTSTART:20250108T113000Z
DTEND:20250108T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/27
DESCRIPTION:Title: Tilting objects for gentle and skew-gentle algebras using the geometri
c model.\nby Claire Amiot (University of Grenoble Alpes) as part 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 Kontsevich and O
pper\, Plamondon and Schroll. In this talk I will explain how to detect ti
lting objects for gentle algebras using this geometric model. This is a jo
int work with Plamondon and Schroll. If time permits\, I will explain how
to generalize these results for skew-gentle algebras. This is a collaborat
ion with Plamondon.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniel Labardini Fragoso (University of Padova)
DTSTART:20250212T113000Z
DTEND:20250212T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/28
DESCRIPTION:Title: Mutations of infinite-dimensional representations\nby Daniel Labar
dini Fragoso (University of Padova) as part of RA Seminar\n\n\nAbstract\nI
will report on an ongoing joint project with Rosie Laking and Lang Mou de
voted to extending Derksen-Weyman-Zelevinsky's mutations of representation
s of quivers with potential from the finite-dimensional setting to the pos
sibly infinite-dimensional one and establishing the good mutation behavior
of several classes of infinite-dimensional representations.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andrea Solotar (University of Buenos Aires)
DTSTART:20250312T113000Z
DTEND:20250312T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/29
DESCRIPTION:by Andrea Solotar (University of Buenos Aires) as part of RA S
eminar\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jeremy Rickard (University of Bristol)
DTSTART:20250409T113000Z
DTEND:20250409T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/30
DESCRIPTION:Title: Are finiteness conditions derived invariant?\nby Jeremy Rickard (U
niversity of Bristol) as part of RA Seminar\n\n\nAbstract\nTwo rings are "
Morita equivalent" if they have equivalent module categories\, and\nif a p
roperty of rings depends only on the module category\, then it is called\n
"Morita invariant". More generally\, two rings are "derived equivalent" if
they\nhave equivalent derived categories\, and if a property of rings dep
ends only on\nthe derived category\, then it is called "derived invariant"
.\n\nFairly recently\, Manuel Saorin asked me if I knew whether right cohe
rence was a\nderived invariant property. I didn't\, but when my long term
memory kicked in\, I\nrealised that an example hidden in my 36 year old Ph
D thesis could be used to\ngive a counterexample.\n\nMost of the talk will
be an introduction to the background to this question and\nvariants\, but
it will finish with some fun examples of rings with strange\nproperties.\
n
LOCATION:https://researchseminars.org/talk/RA-Seminar/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rosanna Laking (Università degli Studi di Verona)
DTSTART:20250514T113000Z
DTEND:20250514T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/31
DESCRIPTION:Title: Wide intervals and closed rigid sets\nby Rosanna Laking (Universit
à degli Studi di Verona) as part of RA Seminar\n\n\nAbstract\nAn old resu
lt of Ringel states that semibricks (i.e.\, sets of pairwise Hom-orthogona
l bricks) in the category modA of finite-dimensional modules over a finite
-dimensional algebra are in bijection with the wide subcategories of modA
(i.e. subcategories that are closed under kernels\, cokernels and extensio
ns). These subcategories are interesting abelian length subcategories of
modA that arise naturally in various contexts throughout the representatio
n theory of A.\n\nIn this talk we will be focusing on one such context: wh
en non-trivial wide subcategories arise as intersections of a torsion clas
s T and a torsion-free class V in modA. Such a pair T and V corresponds t
o an interval in the lattice of torsion pairs in modA that Asai and Pfeife
r call wide intervals. We will report on joint work with Lidia Angeleri H
ügel and Francesco Sentieri in which we show that wide intervals are para
metrised by certain closed sets of the Ziegler spectrum of the unbounded d
erived module category of A.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pu Zhang (Shanghai Jiao Tong University)
DTSTART:20250709T113000Z
DTEND:20250709T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/32
DESCRIPTION:Title: Homological dimension and model structures\nby Pu Zhang (Shanghai
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 c
omplete hereditary cotorsion pair in R-Mod\, where $PGF$ is the class 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 algebra R\
, $(GP_n\, P_n^⊥∩ GP^⊥)$ proves to be a complete and hereditary coto
rsion pair in R-Mod\, where $GP_n$ is the class of modules of Gorenstein p
rojective dimension ≤ n. These cotorsion pairs induce two chains of here
ditary Hovey triples $(PGF_n\,P_n^⊥ \,PGF^⊥)$ and $(GP_n\, P_n^⊥\,
GP^⊥)$\, and the corresponding homotopy categories in the same chain are
the same. It is observed that some complete cotorsion pairs in R-Mod can
induce complete cotorsion pairs in some special extension closed subcatego
ries of R-Mod. Then corresponding results in exact categories $PGF_n\, GP_
n\, GF_n\,PGF^{<∞}\,GP^{<∞}$ and $GF^{<∞}$\, are also obtained. As a
byproduct\, $PGF= GP$ for a ring R if and only if $PGF^⊥ ∩ GP_n= P_n
$ for some $n$.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gustavo Jasso (University of Cologne)
DTSTART:20250910T113000Z
DTEND:20250910T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/33
DESCRIPTION:Title: The Calabi-Yau Auslander-Iyama Correspondence\nby Gustavo Jasso (U
niversity of Cologne) as part of RA Seminar\n\n\nAbstract\nThis talk repor
ts on joint work with Fernando Muro (Sevilla).\nLet d be a positive intege
r. In previous work we established\na bijective correspondence between the
following classes of objects\,\nconsidered up to the appropriate notion o
f equivalence: differential\ngraded algebras with finite-dimensional 0-th
cohomology such that the\ncanonical generator of their perfect derived cat
egory is a basic\ndZ-cluster tilting object\, and basic Frobenius algebras
that are twisted\n(d+2)-periodic as bimodules. For d=1 this correspondenc
e specialises to\nprevious work of the second-named author on algebraic tr
iangulated\ncategories of finite type. In this talk\, I will explain a var
iant of our\ngeneral correspondence for bimodule right Calabi–Yau dg alg
ebras. A\nnovel ingredient is a new cohomology theory that we call bimodul
e\nHochschild–Massey cohomology and which contains obstructions to the\n
existence and uniqueness of minimal A∞-bimodule structures on a graded\n
bimodule.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Khrystyna Serhiyenko (University of Kentucky)
DTSTART:20250611T113000Z
DTEND:20250611T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/34
DESCRIPTION:Title: Classical tilting and tau-tilting theory\nby Khrystyna Serhiyenko
(University of Kentucky) as part of RA Seminar\n\n\nAbstract\nTau-tilting
theory can be thought of as a generalization of the classical tilting theo
ry\, which allows mutations at any indecomposable summand of a support tau
-tilting module. Indeed\, tilting modules are tau-tilting modules and the
y form a subposet of the support tau-tilting poset. Conversely\, we show
that the tau-tilting theory of an algebra can be naturally identified wit
h the classical tilting theory of its duplicated algebra. This extends th
e results of Assem-Brüstle-Schiffler-Todorov in the case of hereditary al
gebras.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/34/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sondre Kvamme (Norwegian University of Science and Technology)
DTSTART:20250813T113000Z
DTEND:20250813T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/35
DESCRIPTION:Title: The reconstruction problem for d-cluster tilting subcategories of exac
t categories\nby Sondre Kvamme (Norwegian University of Science and Te
chnology) as part of RA Seminar\n\n\nAbstract\nWe explain how any weakly i
dempotent complete d-exact category is equivalent to a d-cluster tilting s
ubcategory of a weakly idempotent complete exact category\, and that the e
xact category must be unique up to exact equivalence. We explain how this
gives an answer to the reconstruction problem for d-cluster tilting subcat
egories of exact categories.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/35/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yuya Mizuno (Osaka Metropolitan University)
DTSTART:20251112T113000Z
DTEND:20251112T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/36
DESCRIPTION:Title: On the d-polynomial for preprojective algebras\nby Yuya Mizuno (Os
aka Metropolitan University) as part of RA Seminar\n\n\nAbstract\nIn recen
t years\, $\\tau$-tilting theory and its related theories have been the su
bject of very active research. In this talk\, we will introduce a new conc
ept\, the "d-polynomial\," which is determined from $\\tau$-rigid modules\
, and discuss its properties. \nIn short\, this polynomial represents an e
numeration of the dimensions of $\\tau$-rigid modules and can be regarded
as a measure of homological quantities. I will particularly focus on the p
reprojective algebra of type A\, and explain the close relationship betwee
n the d-polynomial and the Eulerian polynomial in that case. This is based
on joint work with Toshitaka Aoki.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/36/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Charles Paquette (Royal Military College of Canada)
DTSTART:20251008T113000Z
DTEND:20251008T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/37
DESCRIPTION:Title: Brick-directed torsion classes and the notion of brick-splitting\n
by Charles Paquette (Royal Military College of Canada) as part of RA Semin
ar\n\n\nAbstract\nBricks are playing a fundamental role in modern represen
tation theory of algebras. Based on the successful use of representation-d
irected algebras in classification problems\, we introduce the brick-analo
gue version which is that of brick-directed algebra. We show that brick-di
rected algebras can be characterized by many different algebraic and geome
tric aspects of the algebra. In particular\, we show that a brick-finite a
lgebra A is brick-directed if and only if its lattice of torsion classes i
s modular (equivalently\, extremal). This is based on joint work with Sota
Asai\, Kaveh Mousavand and Osamu Iyama.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/37/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eleonore Faber (University of Graz)
DTSTART:20251210T113000Z
DTEND:20251210T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/38
DESCRIPTION:Title: From additive friezes to associahedra\nby Eleonore Faber (Universi
ty of Graz) as part of RA Seminar\n\n\nAbstract\nFrieze patterns of intege
rs were first studied by Coxeter and Conway-Coxeter in the 1970s from a co
mbinatorial perspective. Since the 2000s they had a remarkable renaissance
in cluster theory\, in particular\, in connection with cluster categories
of type A.\nIn this talk\, we consider the variant of nonnegative additiv
e frieze patterns. Our goal is to find a representation theoretic interpre
tation of these friezes through a root category as well as a way to enumer
ate them. Therefore we consider associahedra coming from the cluster categ
ory\, which lead us to a construction of an associahedron for our root cat
egory.\nThis is joint work with Asilata Bapat\, Véronique Bazier-Matte\,
Kunda Kambaso\, Bethany Marsh\, and Yadira Valdivieso.\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/38/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nicholas Williams (University of Cambridge)
DTSTART:20260114T113000Z
DTEND:20260114T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/39
DESCRIPTION:Title: The talk has been postponed to 8 April.\nby Nicholas Williams (Uni
versity of Cambridge) as part of RA Seminar\n\n\nAbstract\nA well-known re
sult of Fomin and Zelevinsky states that clusters in the type A cluster al
gebra are in bijection with triangulations of a convex polygon. In previou
s work\, I showed a three-dimensional version of this bijection\, namely t
hat equivalence classes of maximal green sequences of linearly oriented ty
pe A are in bijection with triangulations of a three-dimensional cyclic po
lytope. It is natural to wonder whether there exist analogous results for
other orientations of the type A Dynkin diagram. Namely\, given such an or
ientation\, is there a polytope whose triangulations correspond to equival
ence classes of maximal green sequences? In this talk I will explain recen
t work which goes some way towards asking this question. Namely\, I show t
hat\, given a cluster-tilting object T in the type A cluster category\, th
ere is an oriented matroid whose stackable triangulations correspond to eq
uivalence classes of maximal green sequences of End(T).\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/39/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jorge Vitoria (University of Padova)
DTSTART:20260211T113000Z
DTEND:20260211T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/40
DESCRIPTION:Title: The talk has been postponed to 13 May.\nby Jorge Vitoria (Universi
ty of Padova) as part of RA Seminar\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/40/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rene Marczinzic (University of Bonn)
DTSTART:20260311T113000Z
DTEND:20260311T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/41
DESCRIPTION:by Rene Marczinzic (University of Bonn) as part of RA Seminar\
n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/41/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nicholas Williams (University of Cambridge)
DTSTART:20260408T113000Z
DTEND:20260408T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/42
DESCRIPTION:Title: Oriented matroids and maximal green sequences of type A cluster algebr
as\nby Nicholas Williams (University of Cambridge) as part of RA Semin
ar\n\n\nAbstract\nA well-known result of Fomin and Zelevinsky states that
clusters in the type A cluster algebra are in bijection with triangulation
s of a convex polygon. In previous work\, I showed a three-dimensional ver
sion of this bijection\, namely that equivalence classes of maximal green
sequences of linearly oriented type A are in bijection with triangulations
of a three-dimensional cyclic polytope. It is natural to wonder whether t
here exist analogous results for other orientations of the type A Dynkin d
iagram. Namely\, given such an orientation\, is there a polytope whose tri
angulations correspond to equivalence classes of maximal green sequences?
In this talk I will explain 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 category\, there is an oriented matroid whose stackabl
e triangulations correspond to equivalence classes of maximal green sequen
ces of End(T).\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/42/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jorge Vitoria (University of Padova)
DTSTART:20260513T113000Z
DTEND:20260513T123000Z
DTSTAMP:20260315T023108Z
UID:RA-Seminar/43
DESCRIPTION:by Jorge Vitoria (University of Padova) as part of RA Seminar\
n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/RA-Seminar/43/
END:VEVENT
END:VCALENDAR