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CALSCALE:GREGORIAN
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BEGIN:VEVENT
SUMMARY:Mima Stanojkovski (Max Planck Institut fur Mathematik)
DTSTART:20201008T120000Z
DTEND:20201008T130000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/1
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/1/">(Strong) isomorphism of p-groups and orbit counting</a>\nby Mima 
 Stanojkovski (Max Planck Institut fur Mathematik) as part of Al@Bicocca ta
 ke-away\n\n\nAbstract\nThe strong isomorphism classes of extensions of fin
 ite groups are parametrized by orbits of a prescribed action on the second
  cohomology group. We will look at these orbits in the case of extensions 
 of a finite abelian p-group by a cyclic factor of order p. As an applicati
 on\, we will compute number and sizes of these orbits when the initial p-g
 roup is generated by at most 3 elements. This is joint work with Oihana Ga
 raialde Ocaña.\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Carmine Monetta (University of Salerno)
DTSTART:20201022T120000Z
DTEND:20201022T130000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/2
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/2/">On the exponent of the non-abelian tensor square and related cons
 tructions of finite p-groups</a>\nby Carmine Monetta (University of Salern
 o) as part of Al@Bicocca take-away\n\n\nAbstract\nAbstract: If $F$ is an o
 perator in the class of finite groups\, it is quite natural to ask whether
  or not it is then possible to bound the exponent of $F(G)$ in terms of th
 e exponent of G only\, where G is a finite group. In 1991\, N. Rocco intro
 duced the operator $\\nu$ which associates to every group G a certain exte
 nsion of the non-abelian tensor square $G\\otimes G$ by $G\\times G$.\n\nI
 n this talk we will give an exposition of a joint work with Raimundo Basto
 s\, Emerson de Melo and Nathalia Goncalves\, where we deal with the restri
 ction of $\\nu$ to the class of finite p-groups\, for p a prime. More prec
 isely\, we address the problem to determine bounds for the exponent of $\\
 nu(G)$ and $G\\otimes G$ when $G$ is a finite p-group. The obtained bounds
  improve some existing ones and depend on the exponent of $G$ and either o
 n the nilpotency class or on the coclass of the finite p-group $G$.\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Scott Harper (University of Bristol)
DTSTART:20201105T130000Z
DTEND:20201105T140000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/5
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/5/">The spread of a finite group</a>\nby Scott Harper (University of 
 Bristol) as part of Al@Bicocca take-away\n\n\nAbstract\nMany interesting a
 nd surprising results have arisen from studying generating sets for groups
 . For example\, every finite simple group has a generating pair\, and more
 over Guralnick and Kantor proved that in a finite simple group every nontr
 ivial element is contained in a generating pair. This talk will focus on r
 ecent work with Burness and Guralnick\, that completely classifies the fin
 ite groups where every nontrivial element is contained in a generating pai
 r and thus settles a 2008 conjecture of Breuer\, Guralnick and Kantor. I w
 ill also give a graph theoretic interpretation of the topic\, highlight ho
 w our work answers a 1975 question of Brenner and Wiegold and discuss what
  is known for infinite groups.\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Francesco Noseda (Federal University of Rio de Janeiro)
DTSTART:20201119T130000Z
DTEND:20201119T140000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/6
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/6/">On self-similarity of p-adic analytic pro-p groups</a>\nby France
 sco Noseda (Federal University of Rio de Janeiro) as part of Al@Bicocca ta
 ke-away\n\n\nAbstract\nA group is said to be self-similar if it admits a s
 uitable kind of action on a regular rooted tree. Albeit it is a natural qu
 estion\, the study of self-similarity of $p$-adic analytic pro-$p$ groups 
 is an uncharted territory. In this talk\, after recalling the basic notion
 s\, we will report on results in this direction obtained in collaboration 
 with Ilir Snopce.\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nicola Grittini (University of Florence)
DTSTART:20201203T143000Z
DTEND:20201203T153000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/7
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/7/">Problems on character theory when we restrict the field of values
 </a>\nby Nicola Grittini (University of Florence) as part of Al@Bicocca ta
 ke-away\n\n\nAbstract\nIrreducible characters of rational and real values 
 have always attracted the attention of researchers in Character theory of 
 finite groups. One of the questions which naturally arise when these chara
 cters are studied\, among the others\, is whether some of the most famous 
 results in character theory have variants involving rational or real value
 d characters. In fact\, some of these results have such variants and\, may
 be not surprisingly\, the variants often involve the prime number 2. An ex
 ample of this fact is a theorem proved in 2007 by Dolfi\, Navarro and Tiep
 . The theorem is a real-valued version of Ito-Michler Theorem and says tha
 t\, if no real-valued irreducible character of a finite group $G$ has even
  order\, then the group has a normal Sylow 2-subgroup.\n\nOn the other han
 d\, it is quite difficult to work with rational and real valued characters
  if we consider a prime number different from 2. This suggests that\, if w
 e want to find variants of some classical results involving character fiel
 ds of values and an odd prime number $p$\, we may not consider as fields $
 \\mathbb{Q}$ and $\\mathbb{R}$ but some other fields\, whose definition in
 volves the prime $p$ and which are equal to $\\mathbb{Q}$ or $\\mathbb{R}$
  when $p= 2$. \n\nIn this talk we will see two cases in which this general
 ization is possible\,one involving rational valued and one involving real 
 valued characters. The part involving real-valued characters has been publ
 ished in a preprint and has to be considered as a work in progress\, never
 theless the approach followed in the study of the problem could be interes
 ting for many researchers in character theory.\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eduardo Martinez-Pedroza (Memorial University of Newfoundland)
DTSTART:20201217T130000Z
DTEND:20201217T140000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/8
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/8/">Quasi-isometric rigidity of subgroups</a>\nby Eduardo Martinez-Pe
 droza (Memorial University of Newfoundland) as part of Al@Bicocca take-awa
 y\n\n\nAbstract\nA central theme in geometric group theory: what are the r
 elations between the algebraic and geometric properties of a finitely gene
 rated group. Finitely generated groups with "equivalent" geometries are ca
 lled quasi-isometric. Let $G$ and $H$ be quasi-isometric finitely generate
 d groups and let $P$ be a subgroup of $G$. Is there a subgroup $Q$ (or a c
 ollection of subgroups) of $H$ whose left cosets coarsely reflect the geom
 etry of the left cosets of $P$ in $G$? We explore sufficient conditions on
  the pair $(G\,P)$ for a positive answer. In the talk\, we introduce notio
 ns of quasi-isometric pairs\, and quasi-isometrically characteristic colle
 ction of subgroups. Distinct classes of qi-characteristic collections of s
 ubgroups have been studied in the literature on quasi-isometric rigidity\,
  we will describe some of them. The talk will focus on putting context to 
 our main result and illustrate it with some applications: If $G$ and $H$ a
 re finitely generated quasi-isometric groups and $P$ is a qi-characteristi
 c collection of subgroups of $G$\, then there is a collection of subgroups
  $Q$ of $H$ such that $(G\, P)$ and $(H\, Q)$ are quasi-isometric pairs.\n
 This is joint work with Jorge Luis Sanchez (UNAM\, Mexico).\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sabino di Trani (University of Florence)
DTSTART:20210114T130000Z
DTEND:20210114T140000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/9
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/9/">Combinatorics of Exterior Algebra\, Graded Multiplicities and Gen
 eralized Exponents of Small Representations</a>\nby Sabino di Trani (Unive
 rsity of Florence) as part of Al@Bicocca take-away\n\n\nAbstract\nLet $\\m
 athfrak{g}$ be a simple Lie algebra over $\\mathbb{C}$\, and consider the 
 exterior algebra $\\wedge\\mathfrak{g}$ as $\\mathfrak{g}$-representations
 . In the talk we will give an overview of some conjectures and of many ele
 gant results proved in the past century about the irreducible decompositio
 n of $\\wedge\\mathfrak{g}$. We will focus on a Conjecture due by Reeder t
 hat generalizes the classical result about invariants in $\\wedge\\mathfra
 k{g}$ to a special class of representations\, called "small". Reeder conje
 ctured that it is possible to compute the graded multiplicities in $\\wedg
 e\\mathfrak{g}$ of this special class of representations reducing to a "We
 yl group representation" problem. We will give an idea of the strategy we 
 used to prove the conjecture in the classical case\, introducing the most 
 relevant instruments we used and we will outline the difficulties we faced
  with. Finally\, we will expose how our formulae can be rearranged involvi
 ng the Generalized Exponents of small representations\, obtaining a genera
 lization of some classical formulae for graded multiplicities in the adjoi
 nt and little adjoint case.\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Albert Garreta (University of the basque Country)
DTSTART:20210128T130000Z
DTEND:20210128T140000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/10
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/10/">The Diophantine problem in commutative rings and solvable groups
 </a>\nby Albert Garreta (University of the basque Country) as part of Al@B
 icocca take-away\n\n\nAbstract\nThe Diophantine problem in a group or ring
  $G$ is decidable if there exists an algorithm that given a finite system 
 of equations with coefficients in $G$ decides whether or not the system ha
 s a solution in $G$. I will overview recent developments that have been ma
 de in regards to this problem in the area of commutative rings and solvabl
 e groups. For large classes of such rings and groups the situation is comp
 letely clarified modulo a big conjecture in number theory. This includes t
 he class of all finitely generated commutative rings (with or without unit
 )\, all finitely generated nilpotent groups\, several polycyclic groups\, 
 and several matrix groups.\nThe talk is based on joint results with Alexei
  Miasnikov and Denis Ovchinnikov .\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yash Lodha (EPFL Losanna)
DTSTART:20210211T130000Z
DTEND:20210211T140000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/11
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/11/">Spaces of enumerated orderable groups</a>\nby Yash Lodha (EPFL L
 osanna) as part of Al@Bicocca take-away\n\n\nAbstract\nAn enumerated group
  is a group structure on the natural numbers.\nGiven one among various not
 ions of orderability of countable groups\,\nwe endow the class of orderabl
 e enumerated groups with a Polish\ntopology.\nIn this setting\, we establi
 sh a plethora of genericity results using\nelementary tools from Baire cat
 egory theory and the Grigorchuk space\nof marked groups.\nIn this talk I w
 ill describe these spaces and some of their striking features.\nThis is on
 going joint work with Srivatsav Kunnawalkam Elayavalli and\nIssac Goldbrin
 g.\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Charles Cox (University of Bristol)
DTSTART:20210225T130000Z
DTEND:20210225T140000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/12
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/12/">Spread and infinite groups</a>\nby Charles Cox (University of Br
 istol) as part of Al@Bicocca take-away\n\n\nAbstract\nMy recent work has i
 nvolved taking questions asked for finite groups and considering them for 
 infinite groups. There are many natural directions with this. In finite gr
 oup theory\, there exist\nmany beautiful results regarding generation prop
 erties. One such notion is that of spread\, which Scott Harper recently ta
 lked about at this seminar (and mentioned several interesting questions th
 at he and Casey Donoven posed for infinite groups in arxiv:1907.05498. A g
 roup $G$ has spread $f$ if for every $g_1\,\\ldots\,g_k$ we can find an $h
 $ in $G$ such that $ G = < g_i\,h > $. For any group we can say that if it
  has a proper quotient that is non-cyclic\, then it cannot have positive s
 pread.\nIn the finite world there is then the astounding result - which is
  the\nwork of many authors - that this condition on proper quotients is no
 t\njust a necessary condition for positive spread: it is also a sufficient
  one.\nBut is this the case for infinite groups? Well\, no. But that’s f
 or the\ntrivial reason that we have infinite simple groups that are not 2-
 generated. So what if we restrict ourselves to 2-generated groups? In this
  talk we’ll see the answer to this question. The arguments will be concr
 ete -at the risk of ruining the punchline\, we will find a 2-generated gro
 up\nthat has every proper quotient cyclic but that has spread zero- and ac
 cessible to a general audience.\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Maria Pia Moscatello (Alma Mater Studiorum - Bologna)
DTSTART:20210311T130000Z
DTEND:20210311T140000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/13
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/13/">Bases for primitive permutation groups</a>\nby Maria Pia Moscate
 llo (Alma Mater Studiorum - Bologna) as part of Al@Bicocca take-away\n\n\n
 Abstract\nThe notion of a base for a permutation group is a fundamental co
 ncept in permutation group theory.  The minimal cardinality of a base is c
 alled the base size of the group. Determining this invariant is a fundamen
 tal problem in permutation groups\, with a long history stretching back to
  the nineteenth century. We will introduce the main motivations to study t
 he base size\, and we will recall some key results about this invariant. W
 e will define the concepts of irredundant bases and we will explain the co
 nnection between these bases and the bases of minimal cardinality. We will
  also review some results about primitive permutation groups having all ir
 redundant bases ofthe same size.\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Slobodan Tanushevski (Fluminense Federal University)
DTSTART:20210325T130000Z
DTEND:20210325T140000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/14
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/14/">Frattini injective pro-$p$ groups</a>\nby Slobodan Tanushevski (
 Fluminense Federal University) as part of Al@Bicocca take-away\n\n\nAbstra
 ct\nA pro-p group $G$ is said to be Frattini-injective if distinct finitel
 y generated subgroups of $G$ have distinct Frattinis. Examples of Frattini
 -injective groups are provided by the maximal pro-$p$ Galois groups of fie
 lds that contain a primitive $p$th root of unity. I will discuss a joint w
 ork with Ilir Snopche in which we make a first attempt to systematically s
 tudy Frattini-injectivity.\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Antonio Ioppolo 🇪🇺 (University of Milano-Bicocca)
DTSTART:20210408T120000Z
DTEND:20210408T130000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/15
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/15/">Polynomial identities in associative algebras</a>\nby Antonio Io
 ppolo 🇪🇺 (University of Milano-Bicocca) as part of Al@Bicocca take-a
 way\n\n\nAbstract\nThe main goal of this talk is to introduce the basic de
 finitions and to present some of the most important results of the theory 
 of polynomial identities (PI-theory) for associative algebras. When an alg
 ebra satisfies a non-trivial polynomial identity we call it a PI-algebra. 
  \n\nLet $A$ be an associative algebra over a field $F$ of characteristic 
 zero and let $c_n(A)$ be its sequence of codimensions. Such a sequence was
  introduced by Regev in '72 and it provide an effective way of measuring t
 he growth of the polynomial identities satisfied by a given algebra. He pr
 oved that any PI-algebra has codimension sequence exponentially bounded.\n
 From that moment\, the sequence of codimensions became a powerful tool in 
 PI-theory and it has been extensively studied by several authors. In this 
 direction\, I shall present two celebrated results. The first one\, proved
  by Kemer\, characterizes those algebras having a polynomial growth of the
  codimension sequence. The second one is a theorem of Giambruno and Zaicev
 \, solving in the affirmative a conjecture of Amitsur.\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eirini Chavli 🇪🇺 (University of Stuttgart)
DTSTART:20210422T120000Z
DTEND:20210422T130000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/16
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/16/">Real properties of generic Hecke algebras</a>\nby Eirini Chavli 
 🇪🇺 (University of Stuttgart) as part of Al@Bicocca take-away\n\n\nAb
 stract\nIwahori  Hecke  algebras  associated  with  real  reflection group
 s  appear  in  the  study  of  finite  reductive  groups.  In  1998  Brou
 é\, Malle  and  Rouquier  generalised  in  a  natural  way  the  definiti
 on  of these algebras to complex case\, known now as generic Hecke algebra
 s. However\,  some  basic  properties  of  the  real  case  were  conjectu
 red  for generic  Hecke  algebras.  In  this  talk  we  will  talk  about 
  these conjectures and their state of the art.\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gareth Tracey 🇬🇧 (University of Oxford)
DTSTART:20210506T120000Z
DTEND:20210506T130000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/17
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/17/">Primitive amalgams the Goldschmidt-Sims conjecture</a>\nby Garet
 h Tracey 🇬🇧 (University of Oxford) as part of Al@Bicocca take-away\n
 \n\nAbstract\nA triple of finite groups $(H\, M\, K)$\, usually written $H
  > M < K$\, is called a primitive amalgam if $M$ is a subgroup of both $H$
  and $K$\, and each of the following holds: (i) whenever $A$ is a normal s
 ubgroup of $H$ contained in $M$\, we have $N_K(A) =M$\; and (ii) whenever 
 $B$ is a normal subgroup of$K$contained in$M$\, we have$N_H(B) =M$. Primit
 ive amalgams arise naturally in many different  contexts across algebra\, 
 from Tutte’s study of vertex-transitive groups of automorphisms of finit
 e\, connected\, trivalent graphs\; to Thompson’s classification of simpl
 e N-groups\; to Sims’ study of point stabilizers inprimitive permutation
  groups\, and beyond. In this talk\, we will discuss some recent progresso
 n the central conjecture from the theory of primitive amalgams\, called th
 e Goldschmidt-Sims conjecture. Joint work with Laszlo Pyber.\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Federico A. Rossi 🇪🇺 (University of Milano-Bicocca)
DTSTART:20210528T090000Z
DTEND:20210528T100000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/18
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/18/">Uniquiness of ad-invariant metrics</a>\nby Federico A. Rossi 
 🇪🇺 (University of Milano-Bicocca) as part of Al@Bicocca take-away\n\
 nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Francesco Fumagalli 🇪🇺 (Unifersity of Florence)
DTSTART:20210603T120000Z
DTEND:20210603T130000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/19
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/19/">An upper bound for the nonsolvable length of a finite group in t
 erms of its shortest law</a>\nby Francesco Fumagalli 🇪🇺 (Unifersity 
 of Florence) as part of Al@Bicocca take-away\n\n\nAbstract\nEvery finite g
 roup $G$ has a normal series each of whose factors is either a solvable gr
 oup or a direct product of non-abelian simple groups. The minimum number o
 f nonsolvable factors\, attained on all possible such series in $G$\, is c
 alled the nonsolvable length $\\lambda(G)$ of $G$. In recent years several
  authors have investigated this invariant and its relation to other releva
 nt parameters. E.g. it has been conjectured by Khukhro and Shumyatsky (as 
 a particular case of a more general conjecture about non-$p$-solvable leng
 th) and Larsen that\, if $\\nu(G)$ is the length of  the  shortest  law  h
 olding in the finite group $G$\, the nonsolvable length of $G$ can be boun
 ded above by some function of $\\nu(G)$. In a joint work with Felix Leinen
  and Orazio Puglisi we have confirmed  this conjecture proving that the in
 equality $\\lambda(G)<\\nu(G)$ holds in every finite group $G$.  This resu
 lt is obtained as a consequence of a result about permutation representati
 ons of finite groups of fixed nonsolvable length. In this talk I will outl
 ine the main ideas behind the proof of our result.\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Giulia Dal Verme 🇪🇺 (University of Bergamo)
DTSTART:20210617T120000Z
DTEND:20210617T130000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/20
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/20/">Groupoid actions on topological spaces and Bass-Serre theory</a>
 \nby Giulia Dal Verme 🇪🇺 (University of Bergamo) as part of Al@Bicoc
 ca take-away\n\n\nAbstract\nThe  so-called  Bass-Serre  theory  gives  a  
 complete  and satisfactory  description  of  groups  acting  on  trees  vi
 a  the  structure theorem. We construct a Bass-Serre theory in the groupoi
 d setting and prove a structure theorem. Groupoids are algebraic objects t
 hat behave like a group (i.e.\, they satisfy conditions of associativity\,
  left and right identities and inverses) except that the multiplication op
 eration is only partially defined. Any groupoid action without inversion o
 f edges on a forest induces a graph of groupoids\, while  any  graph  of  
 groupoids satisfying  certain hypothesis has a canonical associated groupo
 id\, called  the  fundamental  groupoid\,  and a forest\, called the  Bass
 –Serre forest\, such that the fundamental  groupoid  acts  on  the Bass
 –Serre forest. The structure  theorem says that these processes are  mut
 ually inverse\,  so  that  graphs  of  groupoids "encode" groupoid actions
  on forests. One  of  the  main  differences  between the classical  setti
 ng  and the groupoid one  is the following: in  the  classical  setting\, 
 given a group action without inversion on a graph\, one of the ingredients
  used to build a graph of groups is the quotient graph given by such actio
 n\; in the groupoid context\, there is not a canonical graph associated to
  the action of a groupoid on a graph. Hence\, we need to resort to the dif
 ficult notion of desingularization of a groupoid action on a graph.\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Martino Garonzi (University of Brasilia 🇧🇷)
DTSTART:20211015T120000Z
DTEND:20211015T130000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/21
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/21/">Generating graphs and primary coverings</a>\nby Martino Garonzi 
 (University of Brasilia 🇧🇷) as part of Al@Bicocca take-away\n\n\nAbs
 tract\nI will talk about generating graphs and their connection with group
  coverings. I will discuss some recent results and work in progress with F
 umagalli\, Maróti\, Gheri\, Almeida. Then\, I will specialize the discuss
 ion on primary coverings\, i.e.\, coverings of elements of prime power ord
 er.\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniele Garzoni (University of Tel Aviv 🇮🇱)
DTSTART:20211029T120000Z
DTEND:20211029T130000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/22
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/22/">On the number of conjugacy classes of a permutation group</a>\nb
 y Daniele Garzoni (University of Tel Aviv 🇮🇱) as part of Al@Bicocca 
 take-away\n\n\nAbstract\nLet $G$ be a subgroup of $S_n$. What can be said 
 on the number of conjugacy classes of $G$\, in terms of $n$?\nI will revie
 w many results from the literature and give examples. I will then present 
 an upper bound for the case where $G$ is primitive with nonabelian socle. 
 This states that either $G$ belongs to explicit families of examples\, or 
 the number of conjugacy classes is smaller than $n/2$\, and in fact\, it i
 s $o(n)$. I will finish with a few questions. Joint work with Nick Gill.\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ilaria Colazzo 🇬🇧 (University of Exeter)
DTSTART:20211112T130000Z
DTEND:20211112T140000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/23
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/23/">Bijective set-theoretic solutions of the Pentagon Equation</a>\n
 by Ilaria Colazzo 🇬🇧 (University of Exeter) as part of Al@Bicocca ta
 ke-away\n\n\nAbstract\nThe pentagon equation appears in various contexts: 
 for example\, any finite-dimensional Hopf algebra is characterised by an i
 nvertible solution of the Pentagon Equation\, or an arrow is a fusion oper
 ator for a fixed braided monoidal category if it satisfies the Pentagon Eq
 uation. This talk\, based on joint work with E. Jespers and Ł. Kubat\, wi
 ll introduce the basic properties of set-theoretic solutions of the Pentag
 on Equation\, present a complete description of all involutive solutions\,
  and discuss when two involutive solutions are isomorphic.\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sandro Mattarei 🇬🇧 (University of Lincoln 🇬🇧)
DTSTART:20211126T130000Z
DTEND:20211126T140000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/24
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/24/">Graded lie algebras of maximal class</a>\nby Sandro Mattarei 
 🇬🇧 (University of Lincoln 🇬🇧) as part of Al@Bicocca take-away\
 n\n\nAbstract\nThe very same talk delivered 20 hours before at the «GOThI
 C series».\n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Davide Spriano 🇬🇧 (University of Oxford 🇬🇧)
DTSTART:20211210T130000Z
DTEND:20211210T140000Z
DTSTAMP:20260404T095423Z
UID:AlBicocca/25
DESCRIPTION:Title: <a href="https://stable.researchseminars.org/talk/AlBic
 occa/25/">Detecting hyperbolicity in CAT(0) spaces: from cube complexes to
  rank rigidity</a>\nby Davide Spriano 🇬🇧 (University of Oxford 🇬
 🇧) as part of Al@Bicocca take-away\n\n\nAbstract\nCAT(0) spaces form a 
 classical and well-studied class of spaces exhibiting non-positive curvatu
 re behaviour. An important subclass of CAT(0) spaces are CAT(0) cube compl
 exes\, i.e. spaces obtained by gluing Euclidean n-cubes along faces\, sati
 sfying some additional combinatorial conditions. Given a CAT(0) cube compl
 ex\, there are several techniques to construct spaces that "detect the hyp
 erbolic behaviour" of the cube complex\, but all of those techniques rely 
 on the combinatorial structure coming from the cubes. In this talk we will
  present a new approach to construct such spaces that works for general CA
 T(0) spaces\, allowing us to make progress towards the rank-rigidity conje
 cture for CAT(0) spaces. This is joint work with H. Petyt and A. Zalloum.\
 n
LOCATION:https://stable.researchseminars.org/talk/AlBicocca/25/
END:VEVENT
END:VCALENDAR