BEGIN:VCALENDAR
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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:20260422T212928Z
UID:AlBicocca/1
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/1/
 ">(Strong) isomorphism of p-groups and orbit counting</a>\nby Mima Stanojk
 ovski (Max Planck Institut fur Mathematik) as part of Al@Bicocca take-away
 \n\n\nAbstract\nThe strong isomorphism classes of extensions of finite gro
 ups are parametrized by orbits of a prescribed action on the second cohomo
 logy group. We will look at these orbits in the case of extensions of a fi
 nite abelian p-group by a cyclic factor of order p. As an application\, we
  will compute number and sizes of these orbits when the initial p-group is
  generated by at most 3 elements. This is joint work with Oihana Garaialde
  Ocaña.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Carmine Monetta (University of Salerno)
DTSTART:20201022T120000Z
DTEND:20201022T130000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/2
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/2/
 ">On the exponent of the non-abelian tensor square and related constructio
 ns of finite p-groups</a>\nby Carmine Monetta (University of Salerno) as p
 art of Al@Bicocca take-away\n\n\nAbstract\nAbstract: If $F$ is an operator
  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 the expon
 ent of G only\, where G is a finite group. In 1991\, N. Rocco introduced t
 he operator $\\nu$ which associates to every group G a certain extension o
 f the non-abelian tensor square $G\\otimes G$ by $G\\times G$.\n\nIn this 
 talk we will give an exposition of a joint work with Raimundo Bastos\, Eme
 rson de Melo and Nathalia Goncalves\, where we deal with the restriction o
 f $\\nu$ to the class of finite p-groups\, for p a prime. More precisely\,
  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 improv
 e some existing ones and depend on the exponent of $G$ and either on the n
 ilpotency class or on the coclass of the finite p-group $G$.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Scott Harper (University of Bristol)
DTSTART:20201105T130000Z
DTEND:20201105T140000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/5
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/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 and surp
 rising results have arisen from studying generating sets for groups. For e
 xample\, every finite simple group has a generating pair\, and moreover Gu
 ralnick and Kantor proved that in a finite simple group every nontrivial e
 lement is contained in a generating pair. This talk will focus on recent w
 ork with Burness and Guralnick\, that completely classifies the finite gro
 ups where every nontrivial element is contained in a generating pair and t
 hus settles a 2008 conjecture of Breuer\, Guralnick and Kantor. I will als
 o give a graph theoretic interpretation of the topic\, highlight how our w
 ork answers a 1975 question of Brenner and Wiegold and discuss what is kno
 wn for infinite groups.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Francesco Noseda (Federal University of Rio de Janeiro)
DTSTART:20201119T130000Z
DTEND:20201119T140000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/6
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/6/
 ">On self-similarity of p-adic analytic pro-p groups</a>\nby Francesco Nos
 eda (Federal University of Rio de Janeiro) as part of Al@Bicocca take-away
 \n\n\nAbstract\nA group is said to be self-similar if it admits a suitable
  kind of action on a regular rooted tree. Albeit it is a natural question\
 , the study of self-similarity of $p$-adic analytic pro-$p$ groups is an u
 ncharted territory. In this talk\, after recalling the basic notions\, we 
 will report on results in this direction obtained in collaboration with Il
 ir Snopce.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nicola Grittini (University of Florence)
DTSTART:20201203T143000Z
DTEND:20201203T153000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/7
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/7/
 ">Problems on character theory when we restrict the field of values</a>\nb
 y Nicola Grittini (University of Florence) as part of Al@Bicocca take-away
 \n\n\nAbstract\nIrreducible characters of rational and real values have al
 ways attracted the attention of researchers in Character theory of finite 
 groups. One of the questions which naturally arise when these characters a
 re studied\, among the others\, is whether some of the most famous results
  in character theory have variants involving rational or real valued chara
 cters. In fact\, some of these results have such variants and\, maybe not 
 surprisingly\, the variants often involve the prime number 2. An example o
 f this fact is a theorem proved in 2007 by Dolfi\, Navarro and Tiep. The t
 heorem is a real-valued version of Ito-Michler Theorem and says that\, 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 hand\, 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 we want 
 to find variants of some classical results involving character fields of v
 alues and an odd prime number $p$\, we may not consider as fields $\\mathb
 b{Q}$ and $\\mathbb{R}$ but some other fields\, whose definition involves 
 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 generalization
  is possible\,one involving rational valued and one involving real valued 
 characters. The part involving real-valued characters has been published i
 n a preprint and has to be considered as a work in progress\, nevertheless
  the approach followed in the study of the problem could be interesting fo
 r many researchers in character theory.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eduardo Martinez-Pedroza (Memorial University of Newfoundland)
DTSTART:20201217T130000Z
DTEND:20201217T140000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/8
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/8/
 ">Quasi-isometric rigidity of subgroups</a>\nby Eduardo Martinez-Pedroza (
 Memorial University of Newfoundland) as part of Al@Bicocca take-away\n\n\n
 Abstract\nA central theme in geometric group theory: what are the relation
 s between the algebraic and geometric properties of a finitely generated g
 roup. Finitely generated groups with "equivalent" geometries are called qu
 asi-isometric. Let $G$ and $H$ be quasi-isometric finitely generated group
 s and let $P$ be a subgroup of $G$. Is there a subgroup $Q$ (or a collecti
 on of subgroups) of $H$ whose left cosets coarsely reflect the geometry of
  the left cosets of $P$ in $G$? We explore sufficient conditions on the pa
 ir $(G\,P)$ for a positive answer. In the talk\, we introduce notions of q
 uasi-isometric pairs\, and quasi-isometrically characteristic collection o
 f subgroups. Distinct classes of qi-characteristic collections of subgroup
 s have been studied in the literature on quasi-isometric rigidity\, we wil
 l describe some of them. The talk will focus on putting context to our mai
 n result and illustrate it with some applications: If $G$ and $H$ are fini
 tely generated quasi-isometric groups and $P$ is a qi-characteristic colle
 ction 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.\nThis is
  joint work with Jorge Luis Sanchez (UNAM\, Mexico).\n
LOCATION:https://researchseminars.org/talk/AlBicocca/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sabino di Trani (University of Florence)
DTSTART:20210114T130000Z
DTEND:20210114T140000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/9
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/9/
 ">Combinatorics of Exterior Algebra\, Graded Multiplicities and Generalize
 d Exponents of Small Representations</a>\nby Sabino di Trani (University o
 f Florence) as part of Al@Bicocca take-away\n\n\nAbstract\nLet $\\mathfrak
 {g}$ be a simple Lie algebra over $\\mathbb{C}$\, and consider the exterio
 r algebra $\\wedge\\mathfrak{g}$ as $\\mathfrak{g}$-representations. In th
 e talk we will give an overview of some conjectures and of many elegant re
 sults proved in the past century about the irreducible decomposition of $\
 \wedge\\mathfrak{g}$. We will focus on a Conjecture due by Reeder that gen
 eralizes the classical result about invariants in $\\wedge\\mathfrak{g}$ t
 o a special class of representations\, called "small". Reeder conjectured 
 that it is possible to compute the graded multiplicities in $\\wedge\\math
 frak{g}$ of this special class of representations reducing to a "Weyl grou
 p representation" problem. We will give an idea of the strategy we used to
  prove the conjecture in the classical case\, introducing the most relevan
 t instruments we used and we will outline the difficulties we faced with. 
 Finally\, we will expose how our formulae can be rearranged involving the 
 Generalized Exponents of small representations\, obtaining a generalizatio
 n of some classical formulae for graded multiplicities in the adjoint and 
 little adjoint case.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Albert Garreta (University of the basque Country)
DTSTART:20210128T130000Z
DTEND:20210128T140000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/10
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/10
 /">The Diophantine problem in commutative rings and solvable groups</a>\nb
 y Albert Garreta (University of the basque Country) as part of Al@Bicocca 
 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 equa
 tions with coefficients in $G$ decides whether or not the system has a sol
 ution in $G$. I will overview recent developments that have been made in r
 egards to this problem in the area of commutative rings and solvable group
 s. For large classes of such rings and groups the situation is completely 
 clarified modulo a big conjecture in number theory. This includes the clas
 s of all finitely generated commutative rings (with or without unit)\, all
  finitely generated nilpotent groups\, several polycyclic groups\, and sev
 eral matrix groups.\nThe talk is based on joint results with Alexei Miasni
 kov and Denis Ovchinnikov .\n
LOCATION:https://researchseminars.org/talk/AlBicocca/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yash Lodha (EPFL Losanna)
DTSTART:20210211T130000Z
DTEND:20210211T140000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/11
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/11
 /">Spaces of enumerated orderable groups</a>\nby Yash Lodha (EPFL Losanna)
  as part of Al@Bicocca take-away\n\n\nAbstract\nAn enumerated group is a g
 roup structure on the natural numbers.\nGiven one among various notions of
  orderability of countable groups\,\nwe endow the class of orderable enume
 rated groups with a Polish\ntopology.\nIn this setting\, we establish a pl
 ethora of genericity results using\nelementary tools from Baire category t
 heory and the Grigorchuk space\nof marked groups.\nIn this talk I will des
 cribe these spaces and some of their striking features.\nThis is ongoing j
 oint work with Srivatsav Kunnawalkam Elayavalli and\nIssac Goldbring.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Charles Cox (University of Bristol)
DTSTART:20210225T130000Z
DTEND:20210225T140000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/12
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/12
 /">Spread and infinite groups</a>\nby Charles Cox (University of Bristol) 
 as part of Al@Bicocca take-away\n\n\nAbstract\nMy recent work has involved
  taking questions asked for finite groups and considering them for infinit
 e groups. There are many natural directions with this. In finite group the
 ory\, there exist\nmany beautiful results regarding generation properties.
  One such notion is that of spread\, which Scott Harper recently talked ab
 out at this seminar (and mentioned several interesting questions that he a
 nd Casey Donoven posed for infinite groups in arxiv:1907.05498. A group $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 spread.\
 nIn the finite world there is then the astounding result - which is the\nw
 ork of many authors - that this condition on proper quotients is not\njust
  a necessary condition for positive spread: it is also a sufficient one.\n
 But is this the case for infinite groups? Well\, no. But that’s for the\
 ntrivial reason that we have infinite simple groups that are not 2-generat
 ed. So what if we restrict ourselves to 2-generated groups? In this talk w
 e’ll see the answer to this question. The arguments will be concrete -at
  the risk of ruining the punchline\, we will find a 2-generated group\ntha
 t has every proper quotient cyclic but that has spread zero- and accessibl
 e to a general audience.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Maria Pia Moscatello (Alma Mater Studiorum - Bologna)
DTSTART:20210311T130000Z
DTEND:20210311T140000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/13
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/13
 /">Bases for primitive permutation groups</a>\nby Maria Pia Moscatello (Al
 ma Mater Studiorum - Bologna) as part of Al@Bicocca take-away\n\n\nAbstrac
 t\nThe notion of a base for a permutation group is a fundamental concept i
 n permutation group theory.  The minimal cardinality of a base is called t
 he base size of the group. Determining this invariant is a fundamental pro
 blem in permutation groups\, with a long history stretching back to the ni
 neteenth century. We will introduce the main motivations to study the base
  size\, and we will recall some key results about this invariant. We will 
 define the concepts of irredundant bases and we will explain the connectio
 n between these bases and the bases of minimal cardinality. We will also r
 eview some results about primitive permutation groups having all irredunda
 nt bases ofthe same size.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Slobodan Tanushevski (Fluminense Federal University)
DTSTART:20210325T130000Z
DTEND:20210325T140000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/14
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/14
 /">Frattini injective pro-$p$ groups</a>\nby Slobodan Tanushevski (Flumine
 nse Federal University) as part of Al@Bicocca take-away\n\n\nAbstract\nA p
 ro-p group $G$ is said to be Frattini-injective if distinct finitely gener
 ated subgroups of $G$ have distinct Frattinis. Examples of Frattini-inject
 ive groups are provided by the maximal pro-$p$ Galois groups of fields tha
 t contain a primitive $p$th root of unity. I will discuss a joint work wit
 h Ilir Snopche in which we make a first attempt to systematically study Fr
 attini-injectivity.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Antonio Ioppolo 🇪🇺 (University of Milano-Bicocca)
DTSTART:20210408T120000Z
DTEND:20210408T130000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/15
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/15
 /">Polynomial identities in associative algebras</a>\nby Antonio Ioppolo 
 🇪🇺 (University of Milano-Bicocca) as part of Al@Bicocca take-away\n\
 n\nAbstract\nThe main goal of this talk is to introduce the basic definiti
 ons and to present some of the most important results of the theory of pol
 ynomial identities (PI-theory) for associative algebras. When an algebra s
 atisfies a non-trivial polynomial identity we call it a PI-algebra.  \n\nL
 et $A$ be an associative algebra over a field $F$ of characteristic zero a
 nd let $c_n(A)$ be its sequence of codimensions. Such a sequence was intro
 duced by Regev in '72 and it provide an effective way of measuring the gro
 wth of the polynomial identities satisfied by a given algebra. He proved t
 hat any PI-algebra has codimension sequence exponentially bounded.\nFrom t
 hat moment\, the sequence of codimensions became a powerful tool in PI-the
 ory and it has been extensively studied by several authors. In this direct
 ion\, I shall present two celebrated results. The first one\, proved by Ke
 mer\, characterizes those algebras having a polynomial growth of the codim
 ension sequence. The second one is a theorem of Giambruno and Zaicev\, sol
 ving in the affirmative a conjecture of Amitsur.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eirini Chavli 🇪🇺 (University of Stuttgart)
DTSTART:20210422T120000Z
DTEND:20210422T130000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/16
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/16
 /">Real properties of generic Hecke algebras</a>\nby Eirini Chavli 🇪
 🇺 (University of Stuttgart) as part of Al@Bicocca take-away\n\n\nAbstra
 ct\nIwahori  Hecke  algebras  associated  with  real  reflection groups  a
 ppear  in  the  study  of  finite  reductive  groups.  In  1998  Broué\, 
 Malle  and  Rouquier  generalised  in  a  natural  way  the  definition  o
 f these algebras to complex case\, known now as generic Hecke algebras. Ho
 wever\,  some  basic  properties  of  the  real  case  were  conjectured  
 for generic  Hecke  algebras.  In  this  talk  we  will  talk  about  thes
 e conjectures and their state of the art.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gareth Tracey 🇬🇧 (University of Oxford)
DTSTART:20210506T120000Z
DTEND:20210506T130000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/17
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/17
 /">Primitive amalgams the Goldschmidt-Sims conjecture</a>\nby Gareth Trace
 y 🇬🇧 (University of Oxford) as part of Al@Bicocca take-away\n\n\nAbs
 tract\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 subgroup
  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$N_H(B) =M$. Primitive ama
 lgams arise naturally in many different  contexts across algebra\, from Tu
 tte’s study of vertex-transitive groups of automorphisms of finite\, con
 nected\, trivalent graphs\; to Thompson’s classification of simple N-gro
 ups\; to Sims’ study of point stabilizers inprimitive permutation groups
 \, and beyond. In this talk\, we will discuss some recent progresson the c
 entral conjecture from the theory of primitive amalgams\, called the Golds
 chmidt-Sims conjecture. Joint work with Laszlo Pyber.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Federico A. Rossi 🇪🇺 (University of Milano-Bicocca)
DTSTART:20210528T090000Z
DTEND:20210528T100000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/18
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/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://researchseminars.org/talk/AlBicocca/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Francesco Fumagalli 🇪🇺 (Unifersity of Florence)
DTSTART:20210603T120000Z
DTEND:20210603T130000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/19
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/19
 /">An upper bound for the nonsolvable length of a finite group in terms of
  its shortest law</a>\nby Francesco Fumagalli 🇪🇺 (Unifersity of Flor
 ence) as part of Al@Bicocca take-away\n\n\nAbstract\nEvery finite group $G
 $ has a normal series each of whose factors is either a solvable group or 
 a direct product of non-abelian simple groups. The minimum number of nonso
 lvable factors\, attained on all possible such series in $G$\, is called t
 he nonsolvable length $\\lambda(G)$ of $G$. In recent years several author
 s have investigated this invariant and its relation to other relevant para
 meters. E.g. it has been conjectured by Khukhro and Shumyatsky (as a parti
 cular case of a more general conjecture about non-$p$-solvable length) and
  Larsen that\, if $\\nu(G)$ is the length of  the  shortest  law  holding 
 in the finite group $G$\, the nonsolvable length of $G$ can be bounded abo
 ve by some function of $\\nu(G)$. In a joint work with Felix Leinen and Or
 azio Puglisi we have confirmed  this conjecture proving that the inequalit
 y $\\lambda(G)<\\nu(G)$ holds in every finite group $G$.  This result is o
 btained as a consequence of a result about permutation representations of 
 finite groups of fixed nonsolvable length. In this talk I will outline the
  main ideas behind the proof of our result.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Giulia Dal Verme 🇪🇺 (University of Bergamo)
DTSTART:20210617T120000Z
DTEND:20210617T130000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/20
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/20
 /">Groupoid actions on topological spaces and Bass-Serre theory</a>\nby Gi
 ulia Dal Verme 🇪🇺 (University of Bergamo) as part of Al@Bicocca take
 -away\n\n\nAbstract\nThe  so-called  Bass-Serre  theory  gives  a  complet
 e  and satisfactory  description  of  groups  acting  on  trees  via  the 
  structure theorem. We construct a Bass-Serre theory in the groupoid setti
 ng and prove a structure theorem. Groupoids are algebraic objects that beh
 ave like a group (i.e.\, they satisfy conditions of associativity\, left a
 nd right identities and inverses) except that the multiplication operation
  is only partially defined. Any groupoid action without inversion of edges
  on a forest induces a graph of groupoids\, while  any  graph  of  groupoi
 ds satisfying  certain hypothesis has a canonical associated groupoid\, ca
 lled  the  fundamental  groupoid\,  and a forest\, called the  Bass–Serr
 e forest\, such that the fundamental  groupoid  acts  on  the Bass–Serre
  forest. The structure  theorem says that these processes are  mutually in
 verse\,  so  that  graphs  of  groupoids "encode" groupoid actions on fore
 sts. One  of  the  main  differences  between the classical  setting  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 action\; in t
 he groupoid context\, there is not a canonical graph associated to the act
 ion of a groupoid on a graph. Hence\, we need to resort to the difficult n
 otion of desingularization of a groupoid action on a graph.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Martino Garonzi (University of Brasilia 🇧🇷)
DTSTART:20211015T120000Z
DTEND:20211015T130000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/21
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/21
 /">Generating graphs and primary coverings</a>\nby Martino Garonzi (Univer
 sity of Brasilia 🇧🇷) as part of Al@Bicocca take-away\n\n\nAbstract\n
 I will talk about generating graphs and their connection with group coveri
 ngs. I will discuss some recent results and work in progress with Fumagall
 i\, Maróti\, Gheri\, Almeida. Then\, I will specialize the discussion on 
 primary coverings\, i.e.\, coverings of elements of prime power order.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniele Garzoni (University of Tel Aviv 🇮🇱)
DTSTART:20211029T120000Z
DTEND:20211029T130000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/22
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/22
 /">On the number of conjugacy classes of a permutation group</a>\nby Danie
 le Garzoni (University of Tel Aviv 🇮🇱) as part of Al@Bicocca take-aw
 ay\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 review many 
 results from the literature and give examples. I will then present an uppe
 r bound for the case where $G$ is primitive with nonabelian socle. This st
 ates that either $G$ belongs to explicit families of examples\, or the num
 ber of conjugacy classes is smaller than $n/2$\, and in fact\, it is $o(n)
 $. I will finish with a few questions. Joint work with Nick Gill.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ilaria Colazzo 🇬🇧 (University of Exeter)
DTSTART:20211112T130000Z
DTEND:20211112T140000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/23
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/23
 /">Bijective set-theoretic solutions of the Pentagon Equation</a>\nby Ilar
 ia Colazzo 🇬🇧 (University of Exeter) as part of Al@Bicocca take-away
 \n\n\nAbstract\nThe pentagon equation appears in various contexts: for exa
 mple\, any finite-dimensional Hopf algebra is characterised by an invertib
 le solution of the Pentagon Equation\, or an arrow is a fusion operator fo
 r a fixed braided monoidal category if it satisfies the Pentagon Equation.
  This talk\, based on joint work with E. Jespers and Ł. Kubat\, will intr
 oduce the basic properties of set-theoretic solutions of the Pentagon Equa
 tion\, present a complete description of all involutive solutions\, and di
 scuss when two involutive solutions are isomorphic.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sandro Mattarei 🇬🇧 (University of Lincoln 🇬🇧)
DTSTART:20211126T130000Z
DTEND:20211126T140000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/24
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/24
 /">Graded lie algebras of maximal class</a>\nby Sandro Mattarei 🇬🇧 (
 University of Lincoln 🇬🇧) as part of Al@Bicocca take-away\n\n\nAbstr
 act\nThe very same talk delivered 20 hours before at the «GOThIC series»
 .\n
LOCATION:https://researchseminars.org/talk/AlBicocca/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Davide Spriano 🇬🇧 (University of Oxford 🇬🇧)
DTSTART:20211210T130000Z
DTEND:20211210T140000Z
DTSTAMP:20260422T212928Z
UID:AlBicocca/25
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/AlBicocca/25
 /">Detecting hyperbolicity in CAT(0) spaces: from cube complexes to rank r
 igidity</a>\nby Davide Spriano 🇬🇧 (University of Oxford 🇬🇧) as
  part of Al@Bicocca take-away\n\n\nAbstract\nCAT(0) spaces form a classica
 l and well-studied class of spaces exhibiting non-positive curvature behav
 iour. An important subclass of CAT(0) spaces are CAT(0) cube complexes\, i
 .e. spaces obtained by gluing Euclidean n-cubes along faces\, satisfying s
 ome additional combinatorial conditions. Given a CAT(0) cube complex\, the
 re are several techniques to construct spaces that "detect the hyperbolic 
 behaviour" of the cube complex\, but all of those techniques rely on the c
 ombinatorial structure coming from the cubes. In this talk we will present
  a new approach to construct such spaces that works for general CAT(0) spa
 ces\, allowing us to make progress towards the rank-rigidity conjecture fo
 r CAT(0) spaces. This is joint work with H. Petyt and A. Zalloum.\n
LOCATION:https://researchseminars.org/talk/AlBicocca/25/
END:VEVENT
END:VCALENDAR