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BEGIN:VEVENT
SUMMARY:Alessandro Sisto (Heriot-Watt U.)
DTSTART:20200930T190000Z
DTEND:20200930T200000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/1
DESCRIPTION:Title: (Hierarchically) hyperbolic quotients of mapping class groups\nby
Alessandro Sisto (Heriot-Watt U.) as part of Heriot-Watt algebra\, geometr
y and topology seminar (MAXIMALS)\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jean Pierre Mutanguha (Max Planck Institute\, Bonn)
DTSTART:20201007T140000Z
DTEND:20201007T150000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/6
DESCRIPTION:Title: Finding relative immersions of free groups\nby Jean Pierre Mutangu
ha (Max Planck Institute\, Bonn) as part of Heriot-Watt algebra\, geometry
and topology seminar (MAXIMALS)\n\n\nAbstract\nThe overarching goal of tr
ain track theory of free group automorphism is finding the "best" ways to
represent an automorphism so as to read off its dynamical properties. In t
his talk I will describe the progress I made in developing the theory for
injective endomorphisms. To some degree\, it turns out nonsurjective endom
orphisms have simpler dynamics -- a result that I found surprising.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Naomi Andrew (Southampton)
DTSTART:20201028T150000Z
DTEND:20201028T160000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/7
DESCRIPTION:Title: Free-by-cyclic groups and their automorphisms\nby Naomi Andrew (So
uthampton) as part of Heriot-Watt algebra\, geometry and topology seminar
(MAXIMALS)\n\n\nAbstract\nFree-by-cyclic groups are\, on the face of it\,
a fairly nice kind of semidirect product. They are determined by an automo
rphism of a free group\, though\, so perhaps it shouldn't be a surprise th
at they can be hard to understand. We'll see how properties of the definin
g automorphism (for example\, how lengths of words grow as it is iterated)
determine properties of these groups\, and in particular we'll look at th
eir outer automorphism groups\, by investigating their actions on trees. (
This is joint work with Armando Martino.)\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nicolaus Heuer (Oxford)
DTSTART:20201104T150000Z
DTEND:20201104T160000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/8
DESCRIPTION:Title: Stable commutator length on RAAGs\nby Nicolaus Heuer (Oxford) as p
art of Heriot-Watt algebra\, geometry and topology seminar (MAXIMALS)\n\n\
nAbstract\nThe stable commutator length scl(g) of an element g in a group
G measures the least complexity of a surface to “fill” g. Stable commu
tator length on non-abelian free groups is now fairly well understood but
some questions remain open: Which rational numbers arise as scls? What is
the distribution of scl for random elements? What is the gap for chains of
scl?\n\nI will give a partial answer to all of these questions for right-
angled Artin groups (RAAGs). If time permits\, I will also show that compu
ting scl in RAAGs is (unlike in free groups) NP-hard.\n\nThis is joint wor
k with Lvzhou Chen.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Davide Spriano (Oxford)
DTSTART:20201118T150000Z
DTEND:20201118T160000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/9
DESCRIPTION:Title: Generalizing hyperbolicity via local-to-global behaviour\nby Da
vide Spriano (Oxford) as part of Heriot-Watt algebra\, geometry and topolo
gy seminar (MAXIMALS)\n\n\nAbstract\nAn important property of a Gromov hyp
erbolic space is that every path that is locally a quasi-geodesic is gl
obally a quasi-geodesic. A theorem of Gromov states that this is a char
acterization of hyperbolicity\, which means that all the properties of hyp
erbolic spaces and groups can be traced back to this simple fact. In this
talk we generalize this property by considering only Morse quasi-geodes
ic. We show that not only this allows to consider a much larger class of
examples\, such as CAT(0) spaces\, hierarchically hyperbolic spaces and fu
ndamental groups of 3-manifolds\, but also to effortlessly generalize s
everal results from the theory of hyperbolic groups that were previously u
nknown in this generality.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jean Fromentin (Université du Littoral Côte d'Opale)
DTSTART:20201209T150000Z
DTEND:20201209T160000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/10
DESCRIPTION:Title: Experimentation on growth series of braids groups\nby Jean Fromen
tin (Université du Littoral Côte d'Opale) as part of Heriot-Watt algebra
\, geometry and topology seminar (MAXIMALS)\n\n\nAbstract\nWe introduce a
new algorithmic framework to investigate spherical and geodesic growth ser
ies of braid groups relatively to the Artin's or Birman--Ko--Lee's generat
ors. Our experimentations in the case of three and four strands allow us t
o conjecture rational expressions for the spherical growth series with res
pect to the Birman--Ko--Lee's generators.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Laurent Bartholdi (Göttingen)
DTSTART:20201125T150000Z
DTEND:20201125T160000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/12
DESCRIPTION:Title: Dimension series and homotopy groups of spheres\nby Laurent Barth
oldi (Göttingen) as part of Heriot-Watt algebra\, geometry and topology s
eminar (MAXIMALS)\n\n\nAbstract\nThe lower central series of a group $G$ i
s defined by $\\gamma_1=G$ and $\\gamma_n = [G\,\\gamma_{n-1}]$. The "dime
nsion series"\, introduced by Magnus\, is defined using the group algebra
over the integers: $\\delta_n = \\{g: g-1\\text{ belongs to the $n$-th pow
er of the augmentation ideal}\\}$.\n\nIt has been\, for the last 80 years\
, a fundamental problem of group theory to relate these two series. One al
ways has $\\delta_n\\ge\\gamma_n$\, and a conjecture by Magnus\, with fals
e proofs by Cohn\, Losey\, etc.\, claims that they coincide\; but Rips con
structed an example with $\\delta_4/\\gamma_4$ cyclic of order 2. On the p
ositive side\, Sjogren showed that $\\delta_n/\\gamma_n$ is always a torsi
on group\, of exponent bounded by a function of $n$. Furthermore\, it was
believed (and falsely proven by Gupta) that only $2$-torsion may occur.\n\
nIn joint work with Roman Mikhailov\, we prove however that for every prim
e $p$ there is a group with $p$-torsion in some quotient $\\delta_n/\\gamm
a_n$.\n\nEven more interestingly\, I will show that the dimension quotient
$\\delta_n/gamma_n$ is related to the difference between homotopy and hom
ology: our construction is fundamentally based on the order-$p$ element in
the homotopy group $\\pi_{2p}(S^2)$ due to Serre.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nicolas Vaskou (Heriot-Watt)
DTSTART:20201202T150000Z
DTEND:20201202T160000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/13
DESCRIPTION:Title: Acylindrical hyperbolicity for Artin groups of dimension 2\nby Ni
colas Vaskou (Heriot-Watt) as part of Heriot-Watt algebra\, geometry and t
opology seminar (MAXIMALS)\n\n\nAbstract\nIn this talk we will start by in
troducing the notion of Artin groups\, as well as the notion of acylindric
al hyperbolicity. We will see how a large class of Artin groups\, namely t
he two-dimensional Artin groups\, satisfy the latter property\, in the fol
lowing sense :\n\nTheorem : Irreducible two-dimensional Artin groups on a
t least three generators are acylindrically hyperbolic.\n\nIn order to pro
ve this Theorem\, we will look at the action of such Artin groups on their
modified Deligne complex\, a two-dimensional simplicial complex that is n
aturally associated with them. The proof relies on using a variant of the
WPD condition introduced by [Martin]\, for which we will need to study var
ious algebraic and geometric properties of two-dimensional Artin groups.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matthieu Calvez (Heriot-Watt U.)
DTSTART:20210120T150000Z
DTEND:20210120T160000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/14
DESCRIPTION:Title: Garside structures in Artin-Tits groups and acylindrical hyperbolicit
y\nby Matthieu Calvez (Heriot-Watt U.) as part of Heriot-Watt algebra\
, geometry and topology seminar (MAXIMALS)\n\n\nAbstract\nI intend to pres
ent succinctly the construction of the additional length graph associated
to a Garside group. This is a hyperbolic graph on which the group acts by
isometries. Under some mild conditions\, one can show that a Garside group
possesses some elements whose action on the additional length graph is We
akly Partially Discontinuous. This applies in particular to prove that sph
erical and euclidean Artin-Tits groups are acylindrically hyperbolic.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Pallavi Dani (Louisiana State U.)
DTSTART:20210127T150000Z
DTEND:20210127T160000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/15
DESCRIPTION:Title: Subgroups of right-angled Coxeter groups via Stallings-like technique
s\nby Pallavi Dani (Louisiana State U.) as part of Heriot-Watt algebra
\, geometry and topology seminar (MAXIMALS)\n\n\nAbstract\nStallings folds
have been extremely influential in the study of subgroups of free groups.
I will describe joint work with Ivan Levcovitz\, in which we develop an
analogue for the setting of right-angled Coxeter groups\, and use it to pr
ove structural and algorithmic results about their subgroups.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Agata Smoktunowicz (Edinburgh U.)
DTSTART:20210203T150000Z
DTEND:20210203T160000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/16
DESCRIPTION:Title: A review of research utilizing Rump’s notion of a brace\nby Aga
ta Smoktunowicz (Edinburgh U.) as part of Heriot-Watt algebra\, geometry a
nd topology seminar (MAXIMALS)\n\n\nAbstract\nIn around 2005\, in a (succe
ssful!) attempt to describe all involutive\, non-degenerate set theoreti
c solutions of the Yang-Baxter equation\, the notion of a brace was introd
uced by Wolfgang Rump. This formulation then rapidly found application in
other research areas. This talk will review these applications. \n\nDefin
ition. A set $A$ with binary operations of addition $+$\, and multiplicati
on $\\circ $ is a brace if $(A\; +)$ is an abelian group\, $(A\; \\circ)$
is a group and $a\\circ (b+c)+a=a\\circ b+a\\circ c $ for every $a\, b\,
c\\in A$. It follows from this definition that every nilpotent ring with
the usual addition and with multiplication $a\\circ b=ab+a+b$ is a brace.\
n\n Braces have been shown to be equivalent to several concepts in group
theory such as groups with bijective 1-cocycles\, regular subgroups of the
holomorph of abelian groups\, matched pairs of groups and Garside Groups.
There is a connection between braces and grupoids. In 2015\, Gateva-Ivano
va showed that there is a correspondence between braces and braided groups
with an involutive braiding operator. \n\nThere is also a connection betw
een braces and pre-Lie algebras. One generator braces have been show to de
scribe indecomposable\, involutive solutions of the Yang-Baxter equation.\
n\nOn the other hand\, Anastasia Doikou and Robert Weston have recently fo
und fascinating connections between braces and quantum integrable systems
. Solutions of the pentagon equation related to braces have recently been
investigated by several authors.\n\nWe will look at some of the above conn
ections along with some results about braces.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Suraj Krishna M S (Tata Institute of Fundamental Research)
DTSTART:20210210T150000Z
DTEND:20210210T160000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/17
DESCRIPTION:Title: The mapping torus of a torsion-free hyperbolic group is relatively hy
perbolic\nby Suraj Krishna M S (Tata Institute of Fundamental Research
) as part of Heriot-Watt algebra\, geometry and topology seminar (MAXIMALS
)\n\n\nAbstract\nAn important method of studying an automorphism $\\alpha$
of a group $G$ is the mapping torus $G \\rtimes_{\\alpha} \\mathbb{Z}$. I
n a celebrated result\, Thurston showed that if $G$ is the fundamental gro
up of a closed orientable surface of genus at least 2\, then its mapping t
orus is hyperbolic if and only if no power of $\\alpha$ preserves a non-tr
ivial conjugacy class. In this talk\, I will describe joint work with Fran
çois Dahmani\, where we show that if $G$ is torsion-free hyperbolic\, the
n $G\\rtimes_{\\alpha} \\mathbb{Z}$ is relatively hyperbolic with "optimal
" parabolic subgroups.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marissa Miller (Illinois Urbana-Champaign)
DTSTART:20210224T150000Z
DTEND:20210224T160000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/19
DESCRIPTION:Title: Geometry of the genus two handlebody group\nby Marissa Miller (Il
linois Urbana-Champaign) as part of Heriot-Watt algebra\, geometry and top
ology seminar (MAXIMALS)\n\n\nAbstract\nIn this talk\, we explore the geom
etry of the handlebody group\, i.e. the mapping class group of a handlebod
y. This talk will include a heuristic description of hierarchically hyperb
olic spaces\, and using this description\, we will see that the handlebody
group of genus two is a hierarchically hyperbolic group (HHG). Then\, by
analyzing the structure of the maximal hyperbolic space associated to the
handlebody group and utilizing the characterization of stable subgroups of
HHGs\, I will show that the stable subgroups of the genus two handlebody
group are precisely those subgroups whose orbit maps are quasi-isometric e
mbeddings into the disk graph. Lastly\, we will see that various propertie
s of the genus two handlebody group do not hold for higher genus handlebod
y groups.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:André Carvalho (U. Porto)
DTSTART:20210310T150000Z
DTEND:20210310T160000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/20
DESCRIPTION:Title: Endomorphisms of the direct product of two free groups\nby André
Carvalho (U. Porto) as part of Heriot-Watt algebra\, geometry and topolog
y seminar (MAXIMALS)\n\n\nAbstract\nIn this talk\, we will describe the en
domorphisms of the direct product of two free groups of finite rank and sh
ow how this description can be used to solve the Whitehead problems for en
domorphisms\, monomorphisms and automorphisms. The structure of the group
of automorphisms for groups in this class will also be discussed and finit
eness conditions on the fixed and periodic points subgroups will be given.
Finally\, we will briefly present some results on the dynamics of a conti
nuous extension of an endomorphism to the completion of the group when a s
uitable metric is considered.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Thomas Haettel (U. Montpellier)
DTSTART:20210317T150000Z
DTEND:20210317T160000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/21
DESCRIPTION:Title: Group actions on injective metric spaces\nby Thomas Haettel (U. M
ontpellier) as part of Heriot-Watt algebra\, geometry and topology seminar
(MAXIMALS)\n\n\nAbstract\nWe will review isometric actions of groups on i
njective metric spaces and Helly graphs\, which display nonpositive curvat
ure features. We will then present two recent applications. The first one
concerns hierarchically hyperbolic groups and mapping class groups\, and t
his is joint work with Nima Hoda and Harry Petyt. The second one concerns
higher rank uniform lattices in semisimple Lie groups and some Artin group
s.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rylee Lyman (Rutgers)
DTSTART:20210303T133000Z
DTEND:20210303T143000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/22
DESCRIPTION:Title: Folding-like Techniques for CAT(0) Cube Complexes\nby Rylee Lyman
(Rutgers) as part of Heriot-Watt algebra\, geometry and topology seminar
(MAXIMALS)\n\n\nAbstract\nIn a seminal paper\, Stallings introduced foldin
g of morphisms of graphs\, giving effective\, algorithmic answers and proo
fs to classical questions about subgroups of free groups. Recently Dani an
d Levcovitz used Stallings-like methods to study right-angled Coxeter grou
ps\, which act geometrically on CAT(0) cube complexes. With Michael Ben-Zv
i and Robert Kropholler\, I extend their techniques to fundamental groups
of non-positively curved cube complexes. In this talk I will recall Stalli
ngs's folds\, describe how to extend them to non-positively curved cube co
mplexes and discuss some applications.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vaibhav Gadre (U. Glasgow)
DTSTART:20210421T140000Z
DTEND:20210421T150000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/23
DESCRIPTION:Title: Statistical hyperbolicity of Teichmuller spaces\nby Vaibhav Gadre
(U. Glasgow) as part of Heriot-Watt algebra\, geometry and topology semin
ar (MAXIMALS)\n\n\nAbstract\nThe notion of statistical hyperbolicity\, int
roduced by Duchin-Lelievre- Mooney\, encapsulates whether a space is hyper
bolic "on average". More precisely\, a metric space is said to be statisti
cally hyperbolic if the average distance between a pair of points on a lar
ge sphere of radius R approaches 2R as the radius R approaches infinity. W
hile Teichmuller spaces are not hyperbolic in the traditional sense of Gro
mov\, we show that they are statistically hyperbolic for a large class of
natural measures\, including the Lebesgue class measures for which statist
ical hyperbolicity is known by the work of Dowdall-Duchin-Masur. This is
joint work with Luke Jeffreys and Aitor Azemar.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Charles Cox (U. Bristol)
DTSTART:20210428T140000Z
DTEND:20210428T150000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/24
DESCRIPTION:Title: Spread and infinite groups\nby Charles Cox (U. Bristol) as part o
f Heriot-Watt algebra\, geometry and topology seminar (MAXIMALS)\n\n\nAbst
ract\nMy recent work has involved taking questions asked for finite groups
and considering them for infinite groups. There are various natural direc
tions with this. In finite group theory\, there exist many beautiful resul
ts regarding generation properties. One such notion is that of spread\, an
d Scott Harper and Casey Donoven have raised several intriguing questions
for spread for infinite groups (in https://arxiv.org/abs/1907.05498). A gr
oup $G$ has spread $k$ if for every $g_1\, \\dots\, g_k \\in G$ we can fin
d an $h \\in G$ such that $\\langle g_i\, h \\rangle = G$. For any group w
e can say that if it has a proper quotient that is non-cyclic\, then it ha
s spread 0. In the finite world there is then the astounding result - whic
h is the work of many authors - that this condition on proper quotients is
not just a necessary condition for positive spread\, but is also a suffic
ient one. Harper-Donoven’s first question is therefore: is this the case
for infinite groups? Well\, no. But that’s for the trivial reason that
we have infinite simple groups that are not 2-generated (and they point ou
t that 3-generated examples are also known). But if we restrict ourselves
to 2-generated groups\, what happens? In this talk we’ll see the answer
to this question. The arguments will be concrete (*) and accessible to a g
eneral audience.\n\n(*) at the risk of ruining the punchline\, we will fin
d a 2-generated group that has every proper quotient cyclic but that has s
pread zero.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Enric Ventura (U. Politècnica de Catalunya)
DTSTART:20210505T140000Z
DTEND:20210505T150000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/25
DESCRIPTION:Title: Relative order and spectrum of subgroups\nby Enric Ventura (U. Po
litècnica de Catalunya) as part of Heriot-Watt algebra\, geometry and top
ology seminar (MAXIMALS)\n\n\nAbstract\nWe consider a natural generalizati
on of the concept of order of a (torsion) element: the order of $g\\in G$
relative to a subgroup $H\\leq G$ is the minimal $k>0$ such that $g^k\\in
H$\; and the spectrum of $H$ is defined as the set of orders of elements f
rom $G$ relative to $H$. After analyzing the first general properties of t
hese concepts\, we obtain the following results: (1) every set of natural
numbers closed under divisors\, is realizable as the spectrum of a finitel
y generated subgroup $H$ of a finitely generated torsion-free group $G$\;
(2) $F_n\\times F_n$ has undecidable spectrum membership problem: there is
no algorithm to decide\, given a finitely generated subgroup $H$ and a na
tural number $k$\, whether $k$ belongs to the spectrum of $H$\; and (3): i
n free groups F_n (as well as in free-times-free-abelian groups $F_n\\time
s Z^m$) spectrum membership is solvable\, and one can give an explicit alg
orithmic-friendly description of the set of elements of a given order $k$
relative to a given finitely generated subgroup $H$. \n(joint work with J.
Delgado and A. Zakarov)\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ric Wade (U. Oxford)
DTSTART:20210512T140000Z
DTEND:20210512T150000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/26
DESCRIPTION:Title: Rigidity following Ivanov in Aut(F_n) and Out(F_n)\nby Ric Wade (
U. Oxford) as part of Heriot-Watt algebra\, geometry and topology seminar
(MAXIMALS)\n\n\nAbstract\nFollowing Ivanov\, there is a rich history of pr
oving algebraic and geometric rigidity results for mapping class groups us
ing combinatorial rigidity of the curve graph (and variations on this). We
will outline some of this history and some key ideas\, before talking abo
ut how we have been using Ivanov’s approach to study maps between subgro
ups of $\\operatorname{Out}(F_n)$ (in work with Sebastian Hensel and Camil
le Horbez) and commensurations of $\\operatorname{Aut}(F_n)$ (in forthcomi
ng work with Martin Bridson). Some motivating related questions that we ca
n talk about are: “What does rigidity even mean?”\, “What is the cur
ve complex for $\\operatorname{Out}(F_n)$?” and “What is the differenc
e between studying $\\operatorname{Out}(G)$ and $\\operatorname{Aut}(G)$ f
or a group $G$?”\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Robert Kropholler (Münster)
DTSTART:20210623T140000Z
DTEND:20210623T150000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/27
DESCRIPTION:Title: Coarse embeddings and homological filling functions\nby Robert Kr
opholler (Münster) as part of Heriot-Watt algebra\, geometry and topology
seminar (MAXIMALS)\n\n\nAbstract\nThe homological filling function of a f
initely presented group $G$ measures the difficulty of filling loops with
surfaces in a classifying space. The behaviour of this function when passi
ng to finitely presented subgroups is rather wild. If one adds assumptions
on the dimension of $G$\, then one can bound the homological filling func
tion of the subgroup by that of $G$. I will discuss recent work with Mark
Pengitore generalising these results from subgroups to coarse embeddings a
nd also to higher dimensional filling functions.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Valentina Disarlo (Heidelberg)
DTSTART:20210630T140000Z
DTEND:20210630T150000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/28
DESCRIPTION:Title: The model theory of the curve graph\nby Valentina Disarlo (Heidel
berg) as part of Heriot-Watt algebra\, geometry and topology seminar (MAXI
MALS)\n\n\nAbstract\nI will discuss joint work with Javier de la Nuez Gonz
alez (Bilbao) and Thomas Koberda (Virginia) in which we study the curve gr
aph from the point of view of model theory. I will prove that the theory o
f the curve graph is ω--stable\, give bounds on its Morley rank\, and sho
w that it has quantifier elimination with respect to the class of ∃--for
mulae. I will also show that many of the complexes naturally associated to
a surface are interpretable in the curve graph\, which proves that these
complexes are all ω--stable and admit certain a priori bounds on their Mo
rley ranks. I will address the notion of (bi)-interpretability\, which all
ows to compare the logic of theories in different languages\, and potentia
l strategies for finding obstructions to the mutual (bi)-interpretability
of different geometric complexes. This could provide a model theoretical f
rame for Ivanov's metaconjecture.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alex Bishop (U. Sydney)
DTSTART:20211020T140000Z
DTEND:20211020T150000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/29
DESCRIPTION:Title: Towards a classification of geodesic growth in groups\nby Alex Bi
shop (U. Sydney) as part of Heriot-Watt algebra\, geometry and topology se
minar (MAXIMALS)\n\n\nAbstract\nOne of the most well-known results in geom
etric group theory is Gromov theorem which completely classifies the group
s with polynomial volume growth. Bridson\, Burillo\, Elder and Šunić (20
12) asked if such a classification exists for geodesic growth. In this tal
k\, we take steps towards such a classification by providing a nice charac
terisation of the geodesic growth for virtually abelian groups\, and the f
irst example of a virtually 2-step nilpotent group with polynomial geodesi
c growth where previously the only virtually abelian examples were known.\
n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Martín Blufstein (Buenos Aires)
DTSTART:20211027T140000Z
DTEND:20211027T150000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/30
DESCRIPTION:Title: Parabolic subgroups of two-dimensional Artin groups\nby Martín B
lufstein (Buenos Aires) as part of Heriot-Watt algebra\, geometry and topo
logy seminar (MAXIMALS)\n\n\nAbstract\nParabolic subgroups are essential i
n the study of Artin groups. The question of whether the intersection of p
arabolic subgroups of any Artin group is a parabolic subgroup is still ope
n\, but the answer is known in some cases. A recent article by Cumplido\,
Martin and Vaskou introduces a geometric strategy for approaching this que
stion. In this talk we will show how to use this strategy to study the que
stion in the two-dimensional case. To do so\, we will introduce systolic-b
y-function complexes\, which are a generalization of systolic complexes.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chloé Papin (Université Grenoble-Alpes)
DTSTART:20211110T150000Z
DTEND:20211110T160000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/31
DESCRIPTION:Title: A Whitehead algorithm for Generalized Baumslag-Solitar groups\nby
Chloé Papin (Université Grenoble-Alpes) as part of Heriot-Watt algebra\
, geometry and topology seminar (MAXIMALS)\n\n\nAbstract\nBaumslag-Solitar
groups $BS(p\,q) =\\langle a\, t | ta^p t^{-1} = a^q \\rangle$ were first
introduced as examples of non-Hopfian groups. They may be described using
graphs of cyclic groups. In analogy with the study of $Out(F_N)$ one can
study their automorphisms through their action on an "outer space". After
introducing generalized Baumslag-Solitar groups and their actions on trees
\, I will present an analogue of a Whitehead algorithm which takes an elem
ent of a free group and decides whether there exists a free factor which c
ontains that element.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jennifer Taback (Bowdoin College)
DTSTART:20211117T150000Z
DTEND:20211117T160000Z
DTSTAMP:20260314T085828Z
UID:HW_MAXIMALS/32
DESCRIPTION:Title: A new proof of the growth rate of the solvable Baumslag-Solitar group
s\nby Jennifer Taback (Bowdoin College) as part of Heriot-Watt algebra
\, geometry and topology seminar (MAXIMALS)\n\n\nAbstract\nI will describe
a new proof of the growth rate of the solvable Baumslag-Solitar groups BS
(1\,n)\, which was originally computed by Collins\, Edjvet and Gill in 199
4. In joint work with Alden Walker\, we exhibit a regular language of geo
desics for a large set of elements in BS(1\,n) and show that the growth ra
te of this language is the same as the growth rate of the group. We devel
oped these methods and ways of describing geodesic paths in $BS(1\,n)$ in
order to understand conjugation curvature\, as introduced by Bar-Natan\, D
uchin and Kropholler\, for these groups.\n
LOCATION:https://researchseminars.org/talk/HW_MAXIMALS/32/
END:VEVENT
END:VCALENDAR