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TZID:Asia/Jerusalem
X-WR-TIMEZONE:Asia/Jerusalem
BEGIN:VEVENT
UID:32@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20230330T113000
DTEND;TZID=Asia/Jerusalem:20230330T123000
DTSTAMP:20230328T115151Z
URL:https://math.technion.ac.il/en/events/bounds-between-the-time-complexi
ty-of-the-word-problem-of-a-group-and-the-dehn-function-of-its-higman-embe
dding/
SUMMARY:Bounds between the time complexity of the word problem of a group a
nd the Dehn function of its Higman embedding
DESCRIPTION:Lecturer:Bogdan Chornomaz (Technion)\n Location:Amado 719\n PLE
ASE NOTE THE NEW ROOM - AMADO 719\nAbstract: I will talk about a recent re
sult of Frank Wagner and myself\, where we prove that S-machines can emula
te Turing machines in quasilinear time. This implies\, for example\, that
a group G whose word problem can be solved in time T(n) can be isometrical
ly embedded into a finitely presented group H such that the Dehn function
of H is at most $n^2 T(n^2)^{2+\\epsilon}$\, and the Dehn function of G in
H is at most $T(n)^{2+\\epsilon}$\, improving the bounds of Sapir\, Birge
t\, Rips\, and Ol'shanskii ($n^2 T(n^2)^4$ and $T(n)^4$ respectively).\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
BEGIN:VEVENT
UID:39@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20230420T113000
DTEND;TZID=Asia/Jerusalem:20230420T123000
DTSTAMP:20230416T072521Z
URL:https://math.technion.ac.il/en/events/stationary-random-subgroups-in-n
egative-curvature/
SUMMARY:Stationary random subgroups in negative curvature
DESCRIPTION:Lecturer:Arie Levit (TAU)\n Location:Amado 719\n Let G be a ran
k one simple Lie group or an hyperbolic group. In a joint work with Ilya G
ekhtman we show that non-free stationary actions of G have "large" stabili
zers - if the stabilizers are discrete then they have full limit sets and
critical exponents bounded away from 0. As an application\, we use random
walk techniques to obtain a conditional analogue of the recent theorem of
Fraczyk-Gelander in rank one. Namely\, if the bottom of the spectrum of t
he Laplacian on the hyperbolic manifold M is equal to that of its universa
l cover then M has points with arbitrary large injectivity radius.\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
BEGIN:VEVENT
UID:41@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20230424T113000
DTEND;TZID=Asia/Jerusalem:20230424T123000
DTSTAMP:20230416T073703Z
URL:https://math.technion.ac.il/en/events/gromovs-h-principle-for-corank-t
wo-distribution-of-odd-rank-with-maximal-first-kronecker-index/
SUMMARY:Gromov's h-principle for corank two distribution of odd rank with m
aximal first Kronecker index
DESCRIPTION:Lecturer:Igor Zelenko (Texas A&\;M)\n Location:Amado 719\n W
hile establishing various versions of the h-principle for contact distribu
tions (Eliashberg (1989) in dimension 3\, Borman-Eliashberg-Murphy (2015)
in arbitrary dimension\, and even-contact contact (D. McDuff\, 1987) distr
ibutions are among the most remarkable advances in differential topology i
n the last four decades\, very little is known about analogous results for
other classes of distributions\, e.g. generic distributions of corank 2 o
r higher. The smallest dimensional nontrivial case of corank 2 distributio
ns are Engel distributions\, i.e. the maximally nonholonomic rank 2 distri
butions on 4-manifolds. This case is highly nontrivial and was treated rec
ently by Casals-Pérez-del Pino-Presas (2017) and Casals-Pérez-Presas (20
17). In my talk\, I will show how to use the method of convex integration
in order to establish all versions of the h-principle for corank 2 distrib
utions of arbitrary odd rank satisfying a natural generic assumption on th
e associated pencil of skew-symmetric forms. During the talk\, I will try
to give all the necessary background related to the method of convex integ
ration in principle. This is the joint work with Milan Jovanovic\, Javier
Martinez-Aguinaga\, and Alvaro del Pin.\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
BEGIN:VEVENT
UID:48@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20230424T133000
DTEND;TZID=Asia/Jerusalem:20230424T143000
DTSTAMP:20230423T063509Z
URL:https://math.technion.ac.il/en/events/integrable-pdes-and-long-diagona
l-pentagram-maps/
SUMMARY:Integrable PDEs and long-diagonal pentagram maps
DESCRIPTION:Lecturer:Boris Khesin (U of Toronto)\n Location:Amado 719\n The
pentagram map is a beautiful discrete\, completely integrable system with
many relations to other mathematical domains. It was originally defined b
y R.Schwartz in 1992 as a map on plane convex polygons\, where a new polyg
on is spanned by the “shortest” diagonals of the initial one. We descr
ibe various extensions and the geometry of this map in higher dimensions\,
and in particular the recently found long-diagonal maps encompassing know
n integrable cases. We also describe the corresponding continuous limits o
f such maps\, which happen to coincide with equations of the KdV hierarchy
\, generalizing the Boussinesq equation in 2D. This is a joint work with F
edor Soloviev and Anton Izosimov.\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
BEGIN:VEVENT
UID:55@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20230504T113000
DTEND;TZID=Asia/Jerusalem:20230504T123000
DTSTAMP:20230430T070114Z
URL:https://math.technion.ac.il/en/events/automorphisms-of-the-fine-curve-
graph/
SUMMARY:Automorphisms of the fine curve graph
DESCRIPTION:Lecturer:Yvon Verberne (U of Toronto)\n Location:Amado 719\n Th
e fine curve graph of a surface was introduced by Bowden\, Hensel and Webb
. It is defined as the simplicial complex where vertices are essential sim
ple closed curves in the surface and the edges are pairs of disjoint curve
s. We show that the group of automorphisms of the fine curve graph is isom
orphic to the group of homeomorphisms of the surface\, which shows that th
e fine curve graph is a combinatorial tool for studying the group of homeo
morphisms of a surface. This work is joint with Adele Long\, Dan Margalit\
, Anna Pham\, and Claudia Yao.\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
BEGIN:VEVENT
UID:88@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20230608T113000
DTEND;TZID=Asia/Jerusalem:20230608T123000
DTSTAMP:20230606T065124Z
URL:https://math.technion.ac.il/en/events/fighting-chaos-with-chaos/
SUMMARY:Fighting Chaos with Chaos (joint with the GDRT seminar)
DESCRIPTION:Lecturer:Hagai Perets (Technion\, Physics)\n Location:Amado 719
\n I will present a new approach of analytical statistical solutions to th
e three body problem (and other vegetables). No background will be assumed
.\n
CATEGORIES:Geometry and Topology Seminar,Groups, Dynamics and Related
Topics
END:VEVENT
BEGIN:VEVENT
UID:80@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20230615T113000
DTEND;TZID=Asia/Jerusalem:20230615T123000
DTSTAMP:20230601T095825Z
URL:https://math.technion.ac.il/en/events/tba-11/
SUMMARY:Complex geometry and the isometries of the hyperbolic space
DESCRIPTION:Lecturer:Misha Verbitsky (IMPA)\n Location:Amado 719\n The isom
etries of a hyperbolic space are classified into three classes - elliptic\
, parabolic\, and loxodromic\;\nthis classification plays the major role i
n homogeneous dynamics of hyperbolic manifolds. Since the work of Serge Ca
ntat in early 2000-ies it is known that a similar classification exists fo
r complex surfaces\, that is\, compact complex manifolds of dimension 2. T
hese results were recently generalized to holomorphically symplectic manif
olds of arbitrary dimension. I would explain the ergodic properties of the
parabolic automorphisms\, and prove the ergodicity of the automorphism gr
oup action for an appropriate deformation of any compact holomorphically s
ymplectic manifold. This is a joint work with Ekaterina Amerik.\n\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
BEGIN:VEVENT
UID:79@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20230622T113000
DTEND;TZID=Asia/Jerusalem:20230622T123000
DTSTAMP:20230612T083707Z
URL:https://math.technion.ac.il/en/events/tba-10/
SUMMARY:Dynamic and Numeric Aspects of Poisson Brackets Invariants
DESCRIPTION:Lecturer:Itamar Rosenfeld-Rauch\n Location:Amado 719\n The Poi
sson brackets of smooth functions\, {F\, G}\, measure the conservation of
F along Hamiltonian trajectories of G. The $C^0$-semicontinuity of the Poi
sson brackets was proven in 2010 by Entov and Polterovich\, a surprising f
act considering they involve the first derivatives of F\, and G. In this t
alk I will discuss this $C^0$-robustness phenomenon and show how certain v
ariational problems involving the supremum norm of the Poisson brackets gi
ve rise to dynamically flavored invariants. Given time\, I will comment on
a numeric experiment to calculate one such invariant.\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
BEGIN:VEVENT
UID:155@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20240125T113000
DTEND;TZID=Asia/Jerusalem:20240125T123000
DTSTAMP:20240123T071111Z
URL:https://math.technion.ac.il/en/events/cubulating-hyperbolic-mapping-to
ri/
SUMMARY:Cubulating hyperbolic mapping tori
DESCRIPTION:Lecturer:Suraj Krishna M S (Technion)\n Location:Amado 719\n A
group is cubulated if it acts properly and cocompactly on a CAT(0) cube co
mplex\, which is a generalisation of a product of trees. I will show in th
e talk that semidirect products of hyperbolic groups with $\\mathbb{Z}$ wh
ich are again hyperbolic are cubulated\, and give some consequences.\n\nTw
o prominent examples of our setup are (1) mapping tori of fundamental grou
ps of closed hyperbolic surfaces over pseudo-Anosov automorphisms\, and (2
) mapping tori of free groups over atoroidal automorphisms. Both these cla
sses of groups are known to be cubulated by outstanding works. Our proof
uses these two noteworthy results as building blocks and places them in a
unified framework.\n\nBased on joint work with François Dahmani and Jean
Pierre Mutanguha.\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
BEGIN:VEVENT
UID:156@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20240201T113000
DTEND;TZID=Asia/Jerusalem:20240201T123000
DTSTAMP:20240123T093722Z
URL:https://math.technion.ac.il/en/events/almost-representations-and-group
-stability/
SUMMARY:"Almost" Representations and Group Stability
DESCRIPTION:Lecturer:Bharatram Rangarajan\n Location:Amado 719\n \nConsider
the following natural robustness question: is an almost-homomorphism of a
group necessarily a small deformation of a homomorphism? This classical q
uestion of stability goes all the way back to Turing and Ulam\, and can be
posed for different target groups\, and different notions of distance. Gr
oup stability has been an active line of study in recent years\, thanks to
its connections to major open problems like the existence of non-sofic an
d non-hyperlinear groups\, the group Connes embedding problem and the re
cent breakthrough result MIP*=RE\, apart from property testing and error-c
orrecting codes.\nIn this talk\, I will survey some of the main results an
d and questions in this area\, with a focus on cohomological techniques ba
sed on joint works with Glebsky\, Lubotzky\, Monod\, and Fournier-Facio.\n
\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
BEGIN:VEVENT
UID:161@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20240208T113000
DTEND;TZID=Asia/Jerusalem:20240208T123000
DTSTAMP:20240129T121144Z
URL:https://math.technion.ac.il/en/events/a-small-contribution-to-the-kerv
aire-conjecture/
SUMMARY:A small contribution to the Kervaire conjecture
DESCRIPTION:Lecturer:Dani Wise (McGill)\n Location:Amado 719\n I will give
a quick survey of the known results and methods towards the Kervaire conje
cture in combinatorial group theory. Then I will offer a small but pretty
result that offers a new paradigm.\n\nThis is joint work with Andy Ramirez
-Côté.\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
BEGIN:VEVENT
UID:181@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20240215T113000
DTEND;TZID=Asia/Jerusalem:20240215T123000
DTSTAMP:20240211T081544Z
URL:https://math.technion.ac.il/en/events/exotic-and-generic-groups-with-c
ubical-fixed-point-properties/
SUMMARY:Exotic and generic groups with cubical fixed-point properties
DESCRIPTION:Lecturer:Zachary Munro\n Location:Amado 919\n We will discuss c
ubulated groups whose every action on an n-dimensional CAT(0) cube complex
has a global fixed-point. We prove random groups have the n-dimensional f
ixed-point property for all n\, and we demonstrate how to construct a grou
p which acts freely on a locally finite cube complex yet whose every actio
n on a finite dimensional cube complex has a global fixed-point.\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
BEGIN:VEVENT
UID:192@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20240222T113000
DTEND;TZID=Asia/Jerusalem:20240222T123000
DTSTAMP:20240221T072059Z
URL:https://math.technion.ac.il/en/events/hyperbolic-group-with-logarithmi
c-separation-profiles/
SUMMARY:Hyperbolic groups with logarithmic separation profiles
DESCRIPTION:Lecturer:Nir Lazarovich\n Location:Amado 719\n Joint with Coren
tin Le Coz.\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
BEGIN:VEVENT
UID:197@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20240229T113000
DTEND;TZID=Asia/Jerusalem:20240229T123000
DTSTAMP:20240228T065824Z
URL:https://math.technion.ac.il/en/events/the-theory-of-random-groups/
SUMMARY:The Theory of Random Groups
DESCRIPTION:Lecturer:Sobhi Masssalha (HUJI)\n Location:Amado 719\n The Tars
ki conjecture states that two f.g. free gps cannot be distinguished by the
truthness of a given first order sentence. That is\, a given sentence is
true over any f.g. free gp if and only if it is true over the free gp on t
wo generators. Given a sentence\, we can naturally seek for f.g. gps that
can be distinguished from free gps by the given sentence. An open question
in this context states that given a sentence\, the collection of f.g. gps
that can be distinguished from free gps by the given sentence is negligib
le\, that is\, if the sentence is true over f.g. free gps\, then it is tru
e over almost all the f.g. gps. In our talk\, we will present the formal g
round of this question\, and as much as time allows\, we present some of t
he strategies that we plan to use in order to prove it.\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
BEGIN:VEVENT
UID:208@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20240314T113000
DTEND;TZID=Asia/Jerusalem:20240314T123000
DTSTAMP:20240311T122130Z
URL:https://math.technion.ac.il/en/events/free-subgroups-of-sl2c-generated
-by-two-parabolic-elements-and-syllable-length-of-relators/
SUMMARY:Free subgroups of SL(2\,C) generated by two parabolic elements and
syllable length of relators.
DESCRIPTION:Lecturer:Rotem Yaari (TAU)\n Location:Amado 719\n Determining w
hich pairs of parabolic elements of SL(2\, C) generate a free group is a l
ong-standing problem.\nWe will explore and prove certain results before fo
cusing on a collection of subgroups of particular interest\, which is conj
ectured to consist of only non-free subgroups.\nWhile many of those subgr
oups are known to be non-free\, all methods to find such subgroups rely on
the presence of relators of short syllable length. We will explain how to
construct subgroups with no such short relators\, implying that existing
methods might not be suitable for solving the conjecture.\n\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
BEGIN:VEVENT
UID:207@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20240314T153000
DTEND;TZID=Asia/Jerusalem:20240314T163000
DTSTAMP:20240311T121615Z
URL:https://math.technion.ac.il/en/events/combinatorial-transverse-interse
ction-algebra/
SUMMARY:Combinatorial transverse intersection algebra
DESCRIPTION:Lecturer:Ruth Lawrence (HUJI)\n Location:Amado 814\n According
to folklore\, it is impossible to construct a faithful finite dimensional
algebraic model of differential forms\nwhich preserves all three propertie
s of (graded) commutativity\, associativity and the Leibniz rule.\nIn this
talk we will demonstrate how by enlarging a cubical complex by adding cer
tain "ideal" elements\,\na combinatorial transverse intersection algebra m
odel of a torus can be constructed which does have\ngraded commutativity a
nd associativity while the product rule holds for elements of the original
complex.\nOne application of this algebra is to create a finite dimension
al fluid algebra which can be implemented\nnumerically for approximation t
o Euler's equation on a torus.\n\nThis is joint work with Daniel An and De
nnis Sullivan.\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
BEGIN:VEVENT
UID:212@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20240321T113000
DTEND;TZID=Asia/Jerusalem:20240321T123000
DTSTAMP:20240320T070820Z
URL:https://math.technion.ac.il/en/events/algebraic-groups-over-the-free-g
roup/
SUMMARY:Algebraic groups over the free group
DESCRIPTION:Lecturer:Chloé Perin (HUJI)\n Location:Amado 719\n When workin
g over a group instead of a field\, the analogue of a polynomial is just a
word w(x_1\, ...\, x_n) which can involve constants from the group. Follo
wing this analogy\, one can study varieties\, and then algebraic groups (v
arieties endowed with a group law which can be expressed by such a "polyno
mial").\nOver the free group\, varieties are well understood since the wor
ks of Makanin-Razborov and later Sela. In a joint work with Guirardel\, we
show that there are very few irreducible algebraic groups over the free g
roup\, and we describe all such structures. One of the key tools in this w
ork is JSJ decomposition of groups\, which enables us to give a descriptio
n of automorphisms of the coordinate group of such a variety in terms of a
utomorphisms of fundamental groups with boundaries.\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
BEGIN:VEVENT
UID:216@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20240328T113000
DTEND;TZID=Asia/Jerusalem:20240328T123000
DTSTAMP:20240326T074354Z
URL:https://math.technion.ac.il/en/events/confined-subgroups-and-irreducib
le-lattices/
SUMMARY:Confined subgroups and irreducible lattices
DESCRIPTION:Lecturer:Arie Levit (TAU)\n Location:\n A subgroup H <\; G is
called confined if there is a compact subset K of G such that every con
jugate of H intersects K at some point other than identity. We prove that
every confined subgroup of an irreducible lattice in a higher rank sem
isimple Lie group has finite index. Since a non-trivial normal subgroup is
confined\, our result extends the Margulis normal subgroup theorem. We d
o not rely on Kazhdan’s property (T)\, and instead obtain spectral gap f
rom a product structure. More generally\, we show that any confined disc
rete subgroup of a higher rank semisimple Lie group satisfying a certain i
rreducibility condition is a lattice. This extends the recent work of Frac
zyk and Gelander\, removing the property (T) assumption. Joint work with U
ri Bader and Tsachik Gelander.\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
BEGIN:VEVENT
UID:218@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20240404T113000
DTEND;TZID=Asia/Jerusalem:20240404T123000
DTSTAMP:20240326T100909Z
URL:https://math.technion.ac.il/en/events/random-walks-on-affine-buildings
-of-type-a2tilde/
SUMMARY:Random walks on affine buildings of type A2tilde.
DESCRIPTION:Lecturer:Corentin Le Bars (Weizmann)\n Location:Amado 719\n Let
G be a group acting on a separable building X of type A2tilde and let Zn
be a random walk on the group G\, generated by an admissible measure mu. T
he purpose of the talk is to investigate some properties of the measured d
ynamical system Zn.o\, for o a vertex of the building X. Using tools from
boundary theory and the geometry of such buildings\, we can prove that the
re exists a unique mu-stationary measure supported on the chambers of the
spherical building at infinity. If time allows it\, we will discuss some a
pplications about the asymptotic properties of the random walk Zn.o. I wil
l try to introduce most notions: (affine) buildings and their boundaries\,
random walks and stationary measures\, the Poisson-Furstenberg boundary a
nd some of its ergodic properties.\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
BEGIN:VEVENT
UID:227@math.technion.ac.il
DTSTART;TZID=Asia/Jerusalem:20240418T113000
DTEND;TZID=Asia/Jerusalem:20240418T123000
DTSTAMP:20240415T103714Z
URL:https://math.technion.ac.il/en/events/hyperbolic-subgroups-of-type-fp_
2ring/
SUMMARY:Hyperbolic subgroups of type FP_2(Ring)
DESCRIPTION:Lecturer:Shaked Bader (Oxford)\n Location:Amado 814\n In 1996 G
ersten proved that if G is a word hyperbolic group of cohomological dimens
ion 2 and H is a subgroup of type FP_2\, then H is hyperbolic as well. In
this talk\, I will present a project with Robert Kropholler and Vlad Vanko
v generalising this result to show that the same is true if G is only assu
med to have cohomological dimension 2 over some ring R and H is of type FP
_2(R) .\n
CATEGORIES:Geometry and Topology Seminar
END:VEVENT
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