BEGIN:VCALENDAR
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CALSCALE:GREGORIAN
X-WR-CALNAME:researchseminars.org
BEGIN:VEVENT
SUMMARY:Henri Guenancia (CNRS - Univ. Toulouse)
DTSTART;VALUE=DATE-TIME:20200508T150000Z
DTEND;VALUE=DATE-TIME:20200508T163000Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/1
DESCRIPTION:Title: F
amilies of singular Kähler-Einstein metrics\nby Henri Guenancia (CNRS
- Univ. Toulouse) as part of CRM - Séminaire du CIRGET / Géométrie et
Topologie\n\n\nAbstract\nI will outline the main results and ideas from a
recent joint work with E. Di Nezza and V. Guedj. The general theme is as f
ollows: let p:X\\to Y be a holomorphic\, proper surjective map from a comp
lex Kähler space X and assume that the fibers X_y admit some (possibly tw
isted) singular Kähler-Einstein metric. We show that the potentials of th
ese metrics admit uniform bounds when y varies in compact subsets. If time
permits\, I will mention a connection with an earlier work (joint with J.
Cao and M. Paun) on the psh variation of the Kähler-Einstein metric on f
amilies of manifolds of general type.\n
LOCATION:https://researchseminars.org/talk/CIRGET/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ekaterina Amerik (Univ. Paris Sud)
DTSTART;VALUE=DATE-TIME:20200515T150000Z
DTEND;VALUE=DATE-TIME:20200515T163000Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/2
DESCRIPTION:Title: A
round the cone conjecture for hyperkähler manifolds\nby Ekaterina Ame
rik (Univ. Paris Sud) as part of CRM - Séminaire du CIRGET / Géométrie
et Topologie\n\n\nAbstract\nThe Morrison-Kawamata cone conjecture states t
hat the automorphism group of a Calabi-Yau manifold acts with finitely man
y orbits on the set of faces of its ample cone. I shall sketch its proof i
n the hyperkähler case with some emphasis on a statement on Lie groups be
hind it. All results\nare joint work with Misha Verbitsky.\n
LOCATION:https://researchseminars.org/talk/CIRGET/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Patrick Orson (Boston College)
DTSTART;VALUE=DATE-TIME:20200522T150000Z
DTEND;VALUE=DATE-TIME:20200522T163000Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/3
DESCRIPTION:Title: T
opologically embedding spheres in knot traces\nby Patrick Orson (Bosto
n College) as part of CRM - Séminaire du CIRGET / Géométrie et Topologi
e\n\n\nAbstract\nKnot traces are smooth 4-manifolds with boundary\, that a
re homotopic to the 2-sphere\, and obtained by attaching a 2-handle to the
4-ball along a framed knot in the 3-sphere. I will give a complete charac
terisation for when the generator of the second homotopy group of a knot t
race can be represented by a locally flat embedded 2-sphere with abelian e
xterior fundamental group. The answer is in terms of\nclassical and comput
able invariants of the knot. This is a joint project with Feller\, Miller\
, Nagel\, Powell\, and Ray.\n
LOCATION:https://researchseminars.org/talk/CIRGET/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lukas Lewark (Univ. Regensburg)
DTSTART;VALUE=DATE-TIME:20200529T150000Z
DTEND;VALUE=DATE-TIME:20200529T163000Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/4
DESCRIPTION:Title: S
queezed knots\nby Lukas Lewark (Univ. Regensburg) as part of CRM - Sé
minaire du CIRGET / Géométrie et Topologie\n\n\nAbstract\nA knot is call
ed squeezed if it is a slice of a smooth cobordism of minimal genus betwee
n a positive knot and a negative knot. Most small knots are squeezed\, as
are many classes of knots\, such as alternating knots. However\, Khovanov
homology and related tools may obstruct squeezedness. This is joint work i
n progress with Peter Feller and Andrew Lobb.\n
LOCATION:https://researchseminars.org/talk/CIRGET/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ben Weinkove (Northwestern Univ.)
DTSTART;VALUE=DATE-TIME:20200605T150000Z
DTEND;VALUE=DATE-TIME:20200605T163000Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/5
DESCRIPTION:Title: T
he Chern-Ricci flow\nby Ben Weinkove (Northwestern Univ.) as part of C
RM - Séminaire du CIRGET / Géométrie et Topologie\n\n\nAbstract\nThe Ch
ern-Ricci flow is a flow of Hermitian metrics by their Chern-Ricci form.
It generalizes the Kahler-Ricci flow to the setting of non-Kahler metrics
on complex manifolds. I will give an overview of known results for this f
low and describe some open problems.\n
LOCATION:https://researchseminars.org/talk/CIRGET/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eiji Inoue (Tokyo Univ.)
DTSTART;VALUE=DATE-TIME:20200612T150000Z
DTEND;VALUE=DATE-TIME:20200612T163000Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/6
DESCRIPTION:Title: m
u-cscK metrics and muK-stability of polarized manifolds\nby Eiji Inoue
(Tokyo Univ.) as part of CRM - Séminaire du CIRGET / Géométrie et Topo
logie\n\n\nAbstract\nI will talk about a framework unifying both the frame
works on "cscK metrics and K-stability of polarized manifolds" and "Kahler
-Ricci solitons and modified K-stability of Fano manifolds". There are two
divided contents as follows. \n\n1. Formulation of mu-cscK metrics and br
ief remarks on results parallel to the usual canonical metrics. On some at
tractive special features/phenomenon of mu-cscK metrics\; "extremal limit"
and "phase transition". On a little examples. \n\n2. How to formulate/der
ive/express mu-Futaki invariant of test configurations with general singul
arities. On a counterpart of CM line bundle for muK-stability. \n\nIf time
permits\, I will also propose future problems/projects and its applicatio
ns\, especially towards the algebraic moduli problems of Fano varieties ad
mitting Kahler-Ricci solitons.\n
LOCATION:https://researchseminars.org/talk/CIRGET/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Martin Bobb (UT Austin)
DTSTART;VALUE=DATE-TIME:20200626T150000Z
DTEND;VALUE=DATE-TIME:20200626T163000Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/7
DESCRIPTION:Title: D
ecomposition along flats for convex projective manifolds\nby Martin Bo
bb (UT Austin) as part of CRM - Séminaire du CIRGET / Géométrie et Topo
logie\n\n\nAbstract\nReal convex projective geometry generalizes hyperboli
c geometry in a way that allows for interesting deformation theory and als
o aspects of non-positive curvature. In this talk I will introduce convex
projective geometry\, and we will discuss a natural decomposition of compa
ct convex projective manifolds along their codimension-1 flat substructure
s. This extends a celebrated 2006 result of Benoist: a 'geometric JSJ-deco
mposition' for compact convex projective 3-manifolds to manifolds of every
dimension (greater than 2).\n
LOCATION:https://researchseminars.org/talk/CIRGET/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vaibhav Gadre (Univ. of Glasgow)
DTSTART;VALUE=DATE-TIME:20200619T150000Z
DTEND;VALUE=DATE-TIME:20200619T163000Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/8
DESCRIPTION:Title: S
tatistical hyperbolicity of Teichmuller spaces\nby Vaibhav Gadre (Univ
. of Glasgow) as part of CRM - Séminaire du CIRGET / Géométrie et Topol
ogie\n\n\nAbstract\nThe notion of statistical hyperbolicity introduced by
Duchin-Lelievre-Mooney encapsulates whether a space is on average hyperbol
ic at large scales\, that is\, whether average distance between pairs of p
oints on large spheres of radius R is 2R. In this talk\, I will explain ho
w Teichmuller spaces are statistically hyperbolic with respect to stationa
ry measures arising random walks on mapping class groups. This is joint wo
rk with Aitor Azemar and Luke Jeffreys and extends previous work of Dowdal
l-Duchin-Masur.\n
LOCATION:https://researchseminars.org/talk/CIRGET/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gabriele Mondello (Univ. di Roma "Sapienza")
DTSTART;VALUE=DATE-TIME:20200710T150000Z
DTEND;VALUE=DATE-TIME:20200710T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/9
DESCRIPTION:Title: O
n spherical surfaces of genus 1 with 1 conical point\nby Gabriele Mond
ello (Univ. di Roma "Sapienza") as part of CRM - Séminaire du CIRGET / G
éométrie et Topologie\n\n\nAbstract\nA spherical metric on a surface is
a metric of constant curvature 1.\nSuch a metric has a conical point x of
angle $2\\pi\\theta$ if it has vanishing order $(\\theta-1)$ at x.\nA sphe
rical metric in an assigned conformal class can be viewed on one hand as a
solution of a suitable singular Liouville equation.\nOn the other hand\,
when the conformal class is not prescribed\, isotopy classes of spherical
metrics can be considered as flat (SO(3\,R)\,S^2)-structure\, and so their
moduli space has a natural finite-dimensional real-analytic structure.\n\
nI will discuss recent results on the topology of such moduli space of sph
erical metrics with conical points of assigned angles.\nI will then focus
on the case of genus 1 with 1 conical point.\n\nThis is joint work with Er
emenko-Panov and with Eremenko-Gabrielov-Panov.\n
LOCATION:https://researchseminars.org/talk/CIRGET/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nicolina Istrati (Tel Aviv Univ.)
DTSTART;VALUE=DATE-TIME:20200703T150000Z
DTEND;VALUE=DATE-TIME:20200703T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/10
DESCRIPTION:Title:
Variational problems in conformal geometry\nby Nicolina Istrati (Tel A
viv Univ.) as part of CRM - Séminaire du CIRGET / Géométrie et Topologi
e\n\n\nAbstract\nI will present several natural functionals defined on a c
onformal class of almost Hermitian metrics on a compact manifold\, and I w
ill establish their Euler-Lagrange equations. I will show that the Gauduch
on metrics appear naturally as the unique extremal metrics of one such fun
ctional. Next\, a new class of metrics will be introduced\, also appearing
as extremal in complex dimension two. I will show that these new metrics\
, while not Gauduchon in general\, give again unique representatives\, up
to constant multiples\, of conformal classes of almost Hermitian metrics.
This is joint work with D. Angella\, A. Otiman and N. Tardini.\n
LOCATION:https://researchseminars.org/talk/CIRGET/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Joshua Howie (UC Davis)
DTSTART;VALUE=DATE-TIME:20200717T150000Z
DTEND;VALUE=DATE-TIME:20200717T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/11
DESCRIPTION:by Joshua Howie (UC Davis) as part of CRM - Séminaire du CIRG
ET / Géométrie et Topologie\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/CIRGET/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Livio Liechti (Université de Fribourg)
DTSTART;VALUE=DATE-TIME:20200724T150000Z
DTEND;VALUE=DATE-TIME:20200724T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/12
DESCRIPTION:Title:
Divide knots of maximal genus defect\nby Livio Liechti (Université de
Fribourg) as part of CRM - Séminaire du CIRGET / Géométrie et Topologi
e\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/CIRGET/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andrew Lobb (University of Durham\, UK)
DTSTART;VALUE=DATE-TIME:20200911T150000Z
DTEND;VALUE=DATE-TIME:20200911T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/13
DESCRIPTION:Title:
The rectangular peg problem\nby Andrew Lobb (University of Durham\, UK
) as part of CRM - Séminaire du CIRGET / Géométrie et Topologie\n\nAbst
ract: TBA\n
LOCATION:https://researchseminars.org/talk/CIRGET/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Carlo Scarpa (SISSA\, Italy)
DTSTART;VALUE=DATE-TIME:20200918T150000Z
DTEND;VALUE=DATE-TIME:20200918T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/14
DESCRIPTION:Title:
The Hitchin-cscK system\nby Carlo Scarpa (SISSA\, Italy) as part of CR
M - Séminaire du CIRGET / Géométrie et Topologie\n\n\nAbstract\nA class
ic result in the study of Kähler metrics with special curvature propertie
s is that the cscK equation can be realized as the moment map equation for
an infinite-dimensional Kähler reduction. We present a natural hyperkäh
ler extension of this moment map picture\, obtaining a new system of equat
ions reminiscent of Hitchin's equations for Higgs bundles. We will discuss
some recent existence results\, particularly obstructions to solutions to
the problem.\n
LOCATION:https://researchseminars.org/talk/CIRGET/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jonathan Johnson (University of Texas at Austin\, US)
DTSTART;VALUE=DATE-TIME:20200925T150000Z
DTEND;VALUE=DATE-TIME:20200925T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/15
DESCRIPTION:Title:
Bi-Orderability and Pretzel Knots\nby Jonathan Johnson (University of
Texas at Austin\, US) as part of CRM - Séminaire du CIRGET / Géométrie
et Topologie\n\n\nAbstract\nThis talk concerns the bi-orderability of pret
zel knot groups which appears to have a weird connection to the Heegaard F
loer properties of the cyclic branched covers of the knots. In a recent pa
per\, several new examples of bi-orderable pretzel knots are found. We\nwi
ll discuss these results and some of their implications to this strange co
incidence of orderability and Heegaard Floer.\n
LOCATION:https://researchseminars.org/talk/CIRGET/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Junyan Cao (Université de Nice\, France)
DTSTART;VALUE=DATE-TIME:20201002T150000Z
DTEND;VALUE=DATE-TIME:20201002T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/16
DESCRIPTION:Title:
On the Ohsawa-Takegoshi extension theorem\nby Junyan Cao (Université
de Nice\, France) as part of CRM - Séminaire du CIRGET / Géométrie et T
opologie\n\n\nAbstract\nSince it was established\, the Ohsawa-Takegoshi ex
tension theorem turned out to be a fundamental tool in complex geometry. W
e establish a new extension result for twisted canonical forms defined on
a hypersurface with simple normal crossings of a projective manifold with
a control on its L^2 norme. It is a joint work with Mihai Pãun.\n
LOCATION:https://researchseminars.org/talk/CIRGET/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Christina Tonnesen-Friedman (Union College\, US)
DTSTART;VALUE=DATE-TIME:20201009T150000Z
DTEND;VALUE=DATE-TIME:20201009T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/17
DESCRIPTION:Title:
Sasaki-Einstein metrics and the Iterated join\nby Christina Tonnesen-F
riedman (Union College\, US) as part of CRM - Séminaire du CIRGET / Géom
étrie et Topologie\n\n\nAbstract\nIn this talk\, which is based on joint
works with Charles Boyer\, I will discuss the idea of using the join const
ruction in Sasakian Geometry in a non-trivial iterative way in order to ar
rive at some explicit Sasaki-Einstein examples in higher dimensions.\n
LOCATION:https://researchseminars.org/talk/CIRGET/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yi Ni (Caltech\, US)
DTSTART;VALUE=DATE-TIME:20201016T150000Z
DTEND;VALUE=DATE-TIME:20201016T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/18
DESCRIPTION:Title:
Seifert fibered surgeries on hyperbolic fibered knots\nby Yi Ni (Calte
ch\, US) as part of CRM - Séminaire du CIRGET / Géométrie et Topologie\
n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/CIRGET/18/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aru Ray (MPIM Bonn\, Germany)
DTSTART;VALUE=DATE-TIME:20201023T150000Z
DTEND;VALUE=DATE-TIME:20201023T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/19
DESCRIPTION:Title:
Embedding surfaces in 4-manifolds\nby Aru Ray (MPIM Bonn\, Germany) as
part of CRM - Séminaire du CIRGET / Géométrie et Topologie\n\n\nAbstra
ct\nI will present a surface embedding theorem for 4-manifolds with good f
undamental group in the presence of potentially unframed\, immersed dual s
pheres. The essential obstruction is the Kervaire-Milnor invariant and a g
oal of the talk is to describe how it may be computed. This is based on jo
int work with Daniel Kasprowski\, Mark Powell\, and Peter Teichner.\n
LOCATION:https://researchseminars.org/talk/CIRGET/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hugues Auvray (Paris Orsay\, France)
DTSTART;VALUE=DATE-TIME:20201030T150000Z
DTEND;VALUE=DATE-TIME:20201030T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/20
DESCRIPTION:Title:
Noyaux de Bergman sur les surfaces de Riemann épointées\nby Hugues A
uvray (Paris Orsay\, France) as part of CRM - Séminaire du CIRGET / Géom
étrie et Topologie\n\n\nAbstract\nDans des travaux en commun avec X. Ma (
Paris 7) et G. Marinescu (Cologne)\, nous obtenons des asymptotiques raffi
nées pour des noyaux de Bergman calculées à partir de données singuli
ères. On travaille sur le complémentaire d'un nombre fini de points\, vu
s comme singularités\, dans une surface de Riemann compacte\, que l'on mu
nit d'une métrique étendant la métrique cusp de Poincaré autour des si
ngularités \; on se donne également un fibré en droites holomorphe pola
risant pour cette métrique. J'expliquerai comment une description avancé
e du modèle (sur le disque unité épointé) et des techniques de localis
ation dans un contexte à poids permettent de décrire les noyaux de Bergm
an associés à de telles surfaces de Riemann\, et ce jusque aux singulari
tés. \n\nSi le temps le permet\, je préciserai également des interprét
ations géométriques\, voire arithmétiques\, de tels résultats.\n
LOCATION:https://researchseminars.org/talk/CIRGET/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Philip Griffiths (Institute for Advanced Study\, University of Mia
mi)
DTSTART;VALUE=DATE-TIME:20201106T160000Z
DTEND;VALUE=DATE-TIME:20201106T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/21
DESCRIPTION:Title:
Some geometric applications of Hodge theory\nby Philip Griffiths (Inst
itute for Advanced Study\, University of Miami) as part of CRM - Séminair
e du CIRGET / Géométrie et Topologie\n\n\nAbstract\nModern Hodge theory
is both a subject of study in its own right and a subject that is used in
many areas of current mathematical research\, especially in but no means r
estricted to algebraic geometry. This talk will be an informal and partial
overview of some of its uses with emphasis on those in algebraic geometry
. We will also discuss some of the historical development of the subject\;
how did it originate and how did it get to its current state? Here the em
phasis will be on the period up until the time of Hodge and will only touc
h on a few of the major recent milestones.\n
LOCATION:https://researchseminars.org/talk/CIRGET/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Michelle Chu (University of Illinois at Chicago)
DTSTART;VALUE=DATE-TIME:20201113T160000Z
DTEND;VALUE=DATE-TIME:20201113T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/22
DESCRIPTION:Title:
Prescribed virtual torsion in the homology of 3-manifolds\nby Michelle
Chu (University of Illinois at Chicago) as part of CRM - Séminaire du CI
RGET / Géométrie et Topologie\n\n\nAbstract\nHongbin Sun showed that a c
losed hyperbolic 3-manifold virtually contains any prescribed torsion subg
roup as a direct factor in homology. In this talk we will discuss joint wo
rk with Daniel Groves generalizing Sun’s result to irreducible 3-manifol
ds which are not graph-manifolds.\n
LOCATION:https://researchseminars.org/talk/CIRGET/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Neil Hoffman (Oklahoma State University)
DTSTART;VALUE=DATE-TIME:20201120T160000Z
DTEND;VALUE=DATE-TIME:20201120T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/23
DESCRIPTION:Title:
Conjectures related to knot complement commensurability\nby Neil Hoffm
an (Oklahoma State University) as part of CRM - Séminaire du CIRGET / Gé
ométrie et Topologie\n\n\nAbstract\nTwo manifolds $M_1$ and $M_2$ are com
mensurable if there is a third manifold $M_3$ that is a finite sheeted cov
er of $M_1$ and $M_2$. Neumann and Reid conjecture that at most 3 hyperbol
ic knot complements can be commensurable with each other. I will discuss w
hat is known about the conjecture and open questions surrounding commensur
able knot complements.\n
LOCATION:https://researchseminars.org/talk/CIRGET/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mykola Matviichuk (McGill University)
DTSTART;VALUE=DATE-TIME:20201127T160000Z
DTEND;VALUE=DATE-TIME:20201127T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/25
DESCRIPTION:Title:
A local Torelli theorem for log symplectic manifolds\nby Mykola Matvii
chuk (McGill University) as part of CRM - Séminaire du CIRGET / Géométr
ie et Topologie\n\n\nAbstract\nWe will discuss how to deform a holomorphic
symplectic form that has logarithmic poles along a normal crossings divis
or. We will introduce an appropriate deformation complex and explain how t
o calculate its cohomology using natural local systems on the strata of th
e polar divisor. An analysis of the L-infinity structure on the cohomology
of the deformation complex leads to a simple combinatorial description of
the deformation space in terms of the periods of the log symplectic form.
As an application\, we construct new examples of log symplectic forms on
$CP^4$ by deforming previously known ones. This is joint work with Brent P
ym and Travis Schedler.\n
LOCATION:https://researchseminars.org/talk/CIRGET/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matei Toma (Univ. of Nancy)
DTSTART;VALUE=DATE-TIME:20201211T160000Z
DTEND;VALUE=DATE-TIME:20201211T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/26
DESCRIPTION:Title:
Boundedness for sets of coherent analytic sheaves\nby Matei Toma (Univ
. of Nancy) as part of CRM - Séminaire du CIRGET / Géométrie et Topolog
ie\n\n\nAbstract\nA boundedness notion for sets of isomorphism classes of
coherent algebraic sheaves as well as a boundedness criterion were introdu
ced by Grothendieck in his 1961 paper on the construction of the Hilbert s
cheme. In this talk we define boundedness for coherent analytic sheaves an
d present a boundedness criterion in a complex geometric context. We then
show how these apply to prove properties related to Douady spaces or to se
mistability of coherent sheaves\, such as the existence of relative Harder
-Narasimhan filtrations.\n
LOCATION:https://researchseminars.org/talk/CIRGET/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mario Garcia-Fernandez (ICMAT\, Madrid)
DTSTART;VALUE=DATE-TIME:20210115T160000Z
DTEND;VALUE=DATE-TIME:20210115T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/27
DESCRIPTION:Title:
Gravitating vortices with positive curvature\nby Mario Garcia-Fernande
z (ICMAT\, Madrid) as part of CRM - Séminaire du CIRGET / Géométrie et
Topologie\n\n\nAbstract\nIn this talk I will overview recent joint work wi
th Vamsi \nPingali and Chengjian Yao in arXiv:1911.09616 about gravitating
\nvortices. These equations couple a K\\"ahler metric on a compact \nRiem
ann surface with a hermitian metric over a holomorphic line bundle \nequip
ped with a fixed global section --- the Higgs field ---\, and have \na sym
plectic interpretation as moment-map equations.\n\nIn our work we give a c
omplete solution to the existence problem for \ngravitating vortices on th
e Riemann sphere with positive topological \nconstant c > 0. Our main resu
lt establishes the existence of solutions \nprovided that a GIT stability
condition for an effective divisor on \nCP^1 is satisfied. To this end\, w
e use a continuity path starting from \nYang's solution with c = 0. A sali
ent feature of our argument is a new \nbound S \\geq c for the curvature o
f gravitating\nvortices\, which we apply to construct a limiting solution
along the \npath via Cheeger-Gromov theory.\n
LOCATION:https://researchseminars.org/talk/CIRGET/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Simone Diverio (SAPIENZA Università di Roma)
DTSTART;VALUE=DATE-TIME:20210205T160000Z
DTEND;VALUE=DATE-TIME:20210205T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/28
DESCRIPTION:Title:
Pointwise universal Gysin formulae and positivity of some characteristic f
orms\nby Simone Diverio (SAPIENZA Università di Roma) as part of CRM
- Séminaire du CIRGET / Géométrie et Topologie\n\n\nAbstract\nIn the la
st few years there has been a renewed interest around an old conjecture by
Griffiths characterizing which should be the positive characteristic form
s for any given Griffiths positive holomorphic Hermitian vector bundle. Ac
cording to this conjecture\, they should be precisely the characteristic f
orms belonging to the positive cone spanned by the Schur forms.\nAfter rec
alling the various notions of positivity for holomorphic Hermitian vector
bundles\, and how they are (or should be) related\, we shall explain a rec
ent result obtained in collaboration with my PhD student F. Fagioli\, whic
h gives a partial confirmation of the above conjecture.\nSuch a result is
obtained as a consequence of a pointwise\, differential-geometric Gysin fo
rmula for the push-forward of the curvature of the tautological line bundl
es over flag bundles.\n
LOCATION:https://researchseminars.org/talk/CIRGET/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yohan Brunebarbe (Univ. of Bordeaux)
DTSTART;VALUE=DATE-TIME:20210122T160000Z
DTEND;VALUE=DATE-TIME:20210122T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/29
DESCRIPTION:Title:
Higher-dimensional Arakelov inequalities and applications to hyperbolicity
\nby Yohan Brunebarbe (Univ. of Bordeaux) as part of CRM - Séminaire
du CIRGET / Géométrie et Topologie\n\n\nAbstract\nIn this talk\, I will
introduce the so-called Arakelov inequalities (due to Arakelov\, Faltings\
, Peters\, Deligne\, etc.) that one gets from an abelian scheme or more ge
nerally from a variation of Hodge structures on a curve. I will then discu
ss a generalization of these inequalities to higher-dimensional basis\, an
d explain how they can be used to prove hyperbolicity properties of some m
oduli spaces of varieties.\n
LOCATION:https://researchseminars.org/talk/CIRGET/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tarik Aougab (Haverford College)
DTSTART;VALUE=DATE-TIME:20210129T160000Z
DTEND;VALUE=DATE-TIME:20210129T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/30
DESCRIPTION:Title:
Statistics for random curves on surfaces\nby Tarik Aougab (Haverford C
ollege) as part of CRM - Séminaire du CIRGET / Géométrie et Topologie\n
\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/CIRGET/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Allison Miller (Rice University)
DTSTART;VALUE=DATE-TIME:20210212T160000Z
DTEND;VALUE=DATE-TIME:20210212T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/31
DESCRIPTION:Title:
Amphichiral knots with large 4-genera\nby Allison Miller (Rice Univers
ity) as part of CRM - Séminaire du CIRGET / Géométrie et Topologie\n\n\
nAbstract\nAn oriented knot is called negative amphichiral if it is isotop
ic to the reverse of its mirror image. Such knots have order at most two i
n the concordance group\, and many modern concordance invariants vanish on
them. Nevertheless\, we will see that there are negative amphichiral knot
s with arbitrarily large 4-genera\, using Casson-Gordon signature invarian
ts as a primary tool.\n
LOCATION:https://researchseminars.org/talk/CIRGET/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Michael Hallam (Oxford University)
DTSTART;VALUE=DATE-TIME:20210219T160000Z
DTEND;VALUE=DATE-TIME:20210219T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/32
DESCRIPTION:Title:
Stability of fibrations through geodesic analysis\nby Michael Hallam (
Oxford University) as part of CRM - Séminaire du CIRGET / Géométrie et
Topologie\n\n\nAbstract\nA celebrated result in geometry is the Kobayashi-
-Hitchin correspondence\, which states that a holomorphic vector bundle on
a compact Kähler manifold admits a Hermite--Einstein metric if and only
if the bundle is slope polystable. Recently\, Dervan and Sektnan have conj
ectured an analogue of this correspondence for fibrations whose fibres are
compact Kähler manifolds admitting Kähler metrics of constant scalar cu
rvature. Their conjecture is that such a fibration is polystable in a suit
able sense\, if and only if it admits an optimal symplectic connection. In
this talk\, I will provide an introduction to this theory\, and describe
my recent work on the conjecture. Namely\, I show that existence of an opt
imal symplectic connection implies polystability with respect to a large c
lass of fibration degenerations. The techniques used involve analysing geo
desics in the space of relatively Kähler metrics of fibrewise constant sc
alar curvature\, and convexity of the log-norm functional in this setting.
This is work for my PhD thesis\, supervised by Ruadhaí Dervan and France
s Kirwan.\n
LOCATION:https://researchseminars.org/talk/CIRGET/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anthony Conway (MIT)
DTSTART;VALUE=DATE-TIME:20210312T160000Z
DTEND;VALUE=DATE-TIME:20210312T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/33
DESCRIPTION:Title:
Knotted surfaces with infinite cyclic knot group\nby Anthony Conway (M
IT) as part of CRM - Séminaire du CIRGET / Géométrie et Topologie\n\n\n
Abstract\nThis talk will concern embedded surfaces in 4-manifolds for whic
h the fundamental group of the complement is infinite cyclic. Working in t
he topological category\, necessary and sufficient conditions will be give
n for two such surfaces to be isotopic. This is based on joint work with M
ark Powell.\n
LOCATION:https://researchseminars.org/talk/CIRGET/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chris Kottke (New College of Florida)
DTSTART;VALUE=DATE-TIME:20210226T160000Z
DTEND;VALUE=DATE-TIME:20210226T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/34
DESCRIPTION:Title:
Bigerbes and applications\nby Chris Kottke (New College of Florida) as
part of CRM - Séminaire du CIRGET / Géométrie et Topologie\n\n\nAbstra
ct\nGerbes are geometric objects on a space which represent degree 3 integ
er cohomology\, in the same way that complex line bundles (classified by t
he Chern class) represent cohomology in degree 2. Among other settings\, t
hey arise naturally as obstructions to lifting the structure group of a pr
incipal G-bundle to a U(1) central extension of G. \nHigher versions of ge
rbes\, representing cohomology classes of degree 4 and up\, are typically
complicated by higher categorical concepts (2-morphisms and so on) in thei
r definition. In contrast\, bigerbes (and their higher cousins) admit a si
mple\, geometric\, non-higher-categorical description\, and provide a sati
sfactory account of the relationship between so-called `string structures'
on a manifold and `fusion spin structures' on its loop space\, among othe
r applications. This is based on recent joint work with Richard Melrose.\n
LOCATION:https://researchseminars.org/talk/CIRGET/34/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Philipp Naumann (Univ of Bayreuth)
DTSTART;VALUE=DATE-TIME:20210319T160000Z
DTEND;VALUE=DATE-TIME:20210319T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/35
DESCRIPTION:Title:
Curvature formula for direct images of relative canonical bundles with a P
oincaré type twist\nby Philipp Naumann (Univ of Bayreuth) as part of
CRM - Séminaire du CIRGET / Géométrie et Topologie\n\nAbstract: TBA\n\n
We give a curvature formula of the L^2 metric on the direct image of the r
elative canonical bundle twisted by a holomorphic line bundle endowed with
a positive singular metric whose inverse has Poincaré type singularities
along a relative snc divisor. The result applies to families of log canon
ically polarized pairs. Moreover\, we show that it improves the general po
sitivity result of Berndtsson-Paun in a special situation of a big line bu
ndle.\n
LOCATION:https://researchseminars.org/talk/CIRGET/35/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Antonio Alfieri (University of British Columbia)
DTSTART;VALUE=DATE-TIME:20210326T150000Z
DTEND;VALUE=DATE-TIME:20210326T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/36
DESCRIPTION:Title:
Symmetric knots and Floer homologies\nby Antonio Alfieri (University o
f British Columbia) as part of CRM - Séminaire du CIRGET / Géométrie et
Topologie\n\n\nAbstract\nI will discuss some open problems\, and survey s
ome classical material regarding symmetric knots\, and group actions on 3-
and 4-manifolds. In the second part of the talk I will discuss how techni
ques from Floer theory can be employed to approach some of these problems.
Part of this is joint work with Irving Dai\, Abhishek Mallick\, and Sungk
yung Kang.\n
LOCATION:https://researchseminars.org/talk/CIRGET/36/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tye Lidman (North Carolina State University)
DTSTART;VALUE=DATE-TIME:20210507T150000Z
DTEND;VALUE=DATE-TIME:20210507T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/37
DESCRIPTION:Title:
SU(2) representations for toroidal homology spheres\nby Tye Lidman (No
rth Carolina State University) as part of CRM - Séminaire du CIRGET / Gé
ométrie et Topologie\n\n\nAbstract\nThe three-dimensional Poincare conjec
ture shows that any closed three-manifold other than the three-sphere has
non-trivial fundamental group. A natural question is how to measure the no
n-triviality of such a group\, and conjecturally this can be concretely re
alized by a non-trivial representation to SU(2). We will show that the fun
damental groups of three-manifolds with incompressible tori admit non-triv
ial SU(2) representations. This is joint work with Juanita Pinzon-Caicedo
and Raphael Zentner.\n
LOCATION:https://researchseminars.org/talk/CIRGET/37/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Johnny Nicholson (UCL)
DTSTART;VALUE=DATE-TIME:20210423T150000Z
DTEND;VALUE=DATE-TIME:20210423T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/38
DESCRIPTION:Title:
Projective modules and exotic group presentations\nby Johnny Nicholson
(UCL) as part of CRM - Séminaire du CIRGET / Géométrie et Topologie\n\
n\nAbstract\nTwo presentations for a group G which have the same deficienc
y are called exotic if the corresponding presentation complexes are not ho
motopy equivalent. The first examples of exotic presentations were found b
y Dunwoody and Metzler in the 1970s but\, owing to the difficulty of the a
lgebra involved\, few other examples have since been found.\nIn this talk\
, I will discuss a class of finite groups G for which these algebraic diff
iculties can be largely reduced to a question about projective ZG modules
which we resolve. I will also discuss applications to Wall’s D2 problem
and the classification of 4-manifolds.\n
LOCATION:https://researchseminars.org/talk/CIRGET/38/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marco Marengon (Max Planck Institute for Mathematics)
DTSTART;VALUE=DATE-TIME:20210409T150000Z
DTEND;VALUE=DATE-TIME:20210409T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/39
DESCRIPTION:Title:
Relative genus bounds in indefinite 4-manifolds\nby Marco Marengon (Ma
x Planck Institute for Mathematics) as part of CRM - Séminaire du CIRGET
/ Géométrie et Topologie\n\n\nAbstract\nGiven a closed 4-manifold X with
an indefinite intersection form\, we consider smoothly embedded surfaces
in X-int(B^4)\, with boundary a given knot K in the 3-sphere.\nWe give sev
eral methods to bound the genus of such surfaces in a fixed homology class
. Our techniques include adjunction inequalities from Heegaard Floer homol
ogy and the Bauer-Furuta invariants\, and the 10/8 theorem.\nIn particular
\, we present obstructions to a knot being H-slice (that is\, bounding a n
ull-homologous disc) in a 4-manifold and show that the set of H-slice knot
s can detect exotic smooth structures on closed 4-manifolds.\nThis is join
t work with Ciprian Manolescu and Lisa Piccirillo.\n
LOCATION:https://researchseminars.org/talk/CIRGET/39/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Wenhao Ou (Chinese Academy of Science)
DTSTART;VALUE=DATE-TIME:20210430T150000Z
DTEND;VALUE=DATE-TIME:20210430T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/41
DESCRIPTION:Title:
Projective varieties whose tangent bundle contains certain positivity / Va
riétés projectives dont le fibré tangent contient certaine positivité<
/a>\nby Wenhao Ou (Chinese Academy of Science) as part of CRM - Séminaire
du CIRGET / Géométrie et Topologie\n\n\nAbstract\nSince the Frankel con
jecture and the Hartshorne conjecture\, it turns out that the positivity o
f tangent bundle imposes geometric constraints on the ambient manifold. In
this talk\, I will introduce some classic results and my recent works on
these structural theorems.\n\nDepuis la conjecture de Frankel et la conjec
ture de Hartshorne\, il se trouve que la positivité du fibré tangent imp
ose des contraintes géométriques sur la variété ambiante. Dans cet exp
osé\, je vais introduire des résultats classiques et mes travaux récent
s sur ce genre de théorèmes structurels.\n
LOCATION:https://researchseminars.org/talk/CIRGET/41/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ziwen Zhu (Peking University)
DTSTART;VALUE=DATE-TIME:20210514T150000Z
DTEND;VALUE=DATE-TIME:20210514T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/42
DESCRIPTION:Title:
Equivariant K-stability and valuative criteria\nby Ziwen Zhu (Peking U
niversity) as part of CRM - Séminaire du CIRGET / Géométrie et Topologi
e\n\n\nAbstract\nEquivariant K-stability of Fano varieties is defined via
equivariant test configurations. By definition it is weaker than usual K-s
tability. However\, for Fano varieties with large symmetry\, it is often e
asier to check equivariant K-stability. Valuative criterion is developed b
y Chi Li and Kento Fujita to characterize K-stability using valuations. In
this talk\, I will show that there is a parallel theory for equivariant K
-stability by introducing pseudovaluations. As an application\, I will dis
cuss how it can be applied to study K-stability of Fano varieties under fi
nite group action. The talk is partially based on joint work with Yuchen L
iu.\n
LOCATION:https://researchseminars.org/talk/CIRGET/42/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alix Deruelle (Sorbonne Université)
DTSTART;VALUE=DATE-TIME:20210917T150000Z
DTEND;VALUE=DATE-TIME:20210917T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/43
DESCRIPTION:Title:
A relative entropy for expanders of the Ricci flow (joint work with Felix
Schulze\, Warwick University)\nby Alix Deruelle (Sorbonne Université)
as part of CRM - Séminaire du CIRGET / Géométrie et Topologie\n\n\nAbs
tract\nExpanding self-similar solutions of the Ricci flow are solutions wh
ich evolve by scaling and diffeomorphisms only. Such solutions are also ca
lled expanding gradient Ricci solitons. These "canonical" metrics are pote
ntial candidates for smoothing out isolated singularities instantaneously.
These heuristics apply to the Kähler-Ricci flow too. In this talk\, we a
sk the question of uniqueness of such self-similar solutions coming out of
a given metric cone over a smooth link. As a first step\, we make sense o
f a suitable Lyapunov functional also called relative entropy in this sett
ing.\n
LOCATION:https://researchseminars.org/talk/CIRGET/43/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Xuwen Zhu (Northeastern University)
DTSTART;VALUE=DATE-TIME:20210924T150000Z
DTEND;VALUE=DATE-TIME:20210924T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/44
DESCRIPTION:Title:
Constant curvature conical metrics\nby Xuwen Zhu (Northeastern Univers
ity) as part of CRM - Séminaire du CIRGET / Géométrie et Topologie\n\n\
nAbstract\nThe problem of finding and classifying constant curvature metri
cs with conical singularities has a long history bringing together several
different areas of mathematics. This talk will focus on the particularly
difficult spherical case where many new phenomena appear. When some of the
cone angles are bigger than $2\\pi$\, uniqueness fails and existence is n
ot guaranteed\; smooth deformation is not always possible and the moduli s
pace is expected to have singular strata. I will give a survey of several
recent results regarding this singular uniformization problem\, connecting
microlocal techniques with complex analysis and synthetic geometry. Based
on joint works with Rafe Mazzeo\, Bin Xu\, and Mikhail Karpukhin.\n
LOCATION:https://researchseminars.org/talk/CIRGET/44/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Peter Feller (ETH Zurich)
DTSTART;VALUE=DATE-TIME:20211015T150000Z
DTEND;VALUE=DATE-TIME:20211015T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/45
DESCRIPTION:Title:
Braids\, quasimorphisms\, and slice-Bennequin inequalities\nby Peter F
eller (ETH Zurich) as part of CRM - Séminaire du CIRGET / Géométrie et
Topologie\n\n\nAbstract\nThe writhe of a braid (=#pos crossing - #neg cro
ssings) and the fractional Dehn twist coefficient of a braid (a rational n
umber that measures "how much the braid twists") are the two most prominen
t examples of what is known as a quasimorphism (a map that fails to be a g
roup homomorphism by at most a bounded amount) from Artin's braid group on
n-strands to the reals. We consider characterizing properties for such qu
asimorphisms and talk about relations to the study of knot concordance. Fo
r the latter\, we consider inequalities for quasimorphisms modelled after
the so-called slice-Bennequin inequality: writhe(B) <= 2g_4(K) - 1 + n for
all n-stranded braids B with closure a knot K. Based on work in progress.
\n
LOCATION:https://researchseminars.org/talk/CIRGET/45/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yang Li (MIT)
DTSTART;VALUE=DATE-TIME:20211022T150000Z
DTEND;VALUE=DATE-TIME:20211022T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/46
DESCRIPTION:Title:
Metric SYZ conjecture\nby Yang Li (MIT) as part of CRM - Séminaire du
CIRGET / Géométrie et Topologie\n\n\nAbstract\nI will discuss my recent
work on the metric aspect of the Strominger-Yau-Zaslow conjecture\, focus
ing mostly on the Fermat family of hypersurfaces. The conjecture asks for
the existence of special Lagrangian torus fibrations for Calabi-Yau manifo
lds near the large complex structure limit\, at least in the generic regio
n of the manifold. The key is to prove a metric asymptote in the limit\, a
nd time permitting I will try to mention some ingredients.\n
LOCATION:https://researchseminars.org/talk/CIRGET/46/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marco Golla (University of Nantes)
DTSTART;VALUE=DATE-TIME:20211029T150000Z
DTEND;VALUE=DATE-TIME:20211029T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/47
DESCRIPTION:Title:
3-manifolds that bound no definite 4-manifold\nby Marco Golla (Univers
ity of Nantes) as part of CRM - Séminaire du CIRGET / Géométrie et Topo
logie\n\n\nAbstract\nAll 3-manifolds bound 4-manifolds\, and many construc
tions of 3-manifolds automatically come with a 4-manifold bounding it. Oft
entimes these 4-manifolds have definite intersection form. Using Heegaard
Floer correction terms and an analysis of short characteristic covectors i
n bimodular lattices\, we give an obstruction for a 3-manifold to bound a
definite 4-manifold\, and produce some concrete examples. This is joint wo
rk with Kyle Larson.\n
LOCATION:https://researchseminars.org/talk/CIRGET/47/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ruadhai Dervan (University of Cambridge)
DTSTART;VALUE=DATE-TIME:20211112T160000Z
DTEND;VALUE=DATE-TIME:20211112T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/48
DESCRIPTION:Title:
Stability conditions for polarised varieties\nby Ruadhai Dervan (Unive
rsity of Cambridge) as part of CRM - Séminaire du CIRGET / Géométrie et
Topologie\n\n\nAbstract\nA central theme of complex geometry is the relat
ionship between differential-geometric PDEs and algebro-geometric notions
of stability. Examples include Hermitian Yang-Mills connections and Kähle
r-Einstein metrics on the PDE side\, and slope stability and K-stability o
n the algebro-geometric side. I will describe a general framework associat
ing geometric PDEs on complex manifolds to notions of stability\, and will
sketch a proof showing that existence of solutions is equivalent to stabi
lity in a model case. The framework can be seen as an analogue in the sett
ing of varieties of Bridgeland's stability conditions on triangulated cate
gories.\n
LOCATION:https://researchseminars.org/talk/CIRGET/48/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ya Deng (CNRS\, Université de Lorraine)
DTSTART;VALUE=DATE-TIME:20211119T160000Z
DTEND;VALUE=DATE-TIME:20211119T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/49
DESCRIPTION:Title:
Big Picard theorem for varieties admitting nilpotent harmonic bundles\
nby Ya Deng (CNRS\, Université de Lorraine) as part of CRM - Séminaire d
u CIRGET / Géométrie et Topologie\n\n\nAbstract\nThe big Picard theorem
states that any holomorphic map from the punctured disk into the Riemann s
phere avoiding three points must extend across the origin. In this talk I
will explain a generalized big picard theorem for quasi-compact Kähler ma
nifolds U endowed with a nilpotent harmonic bundle whose Higgs field is in
jective at one point. Moreover\, we prove that there is a finite unramifi
ed cover V of U from a quasi-projective manifold V so that the big Picard
theorem holds for any projective compactification of V. This work is based
on the joint work with Benoit Cadorel.\n
LOCATION:https://researchseminars.org/talk/CIRGET/49/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gilles Carron (Université de Nantes)
DTSTART;VALUE=DATE-TIME:20211126T160000Z
DTEND;VALUE=DATE-TIME:20211126T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/50
DESCRIPTION:Title:
Kato's Limits\nby Gilles Carron (Université de Nantes) as part of CRM
- Séminaire du CIRGET / Géométrie et Topologie\n\n\nAbstract\nIt is a
joint work with I. Mondello (Paris XII) and D. Tewodrose (UL Bruxelles\, N
antes). A Kato bound on the Ricci curvature yields nice geometric properti
es ( eigenvalue lower bound\, heat kernel estimates...)\; in particular it
implies a doubling condition for the Riemannian volume and hence a precom
pactness result in the Gromov-Hausdorff topology. We have obtained results
that are generalization of the ones of Cheeger and Colding (where a unifo
rm lower bound on the Ricci curvature is assumed).\n
LOCATION:https://researchseminars.org/talk/CIRGET/50/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nathan Grieve (RMC/Carleton/UQAM)
DTSTART;VALUE=DATE-TIME:20211210T160000Z
DTEND;VALUE=DATE-TIME:20211210T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/51
DESCRIPTION:Title:
On topics that surround the Cone Theorem\, K-stability and Diophantine Ari
thmetic Geometry\nby Nathan Grieve (RMC/Carleton/UQAM) as part of CRM
- Séminaire du CIRGET / Géométrie et Topologie\n\n\nAbstract\nI will su
rvey concepts that are near to the Cone Theorem and MMP (for klt pairs)\,
the question of K-stability for polarized projective varieties and their D
iophantine arithmetic consequences. In doing so\, I will report on some r
ecent and ongoing work. As one example\, I intend to propose a concept of
slope stability\, for polarized projective varieties\, from the viewpoint
of the extremal ray theory. The idea is that it should extend the tradit
ional concept of slope stability\, which is measured along a subvariety.\n
LOCATION:https://researchseminars.org/talk/CIRGET/51/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sucharit Sarkar (UCLA)
DTSTART;VALUE=DATE-TIME:20211105T153000Z
DTEND;VALUE=DATE-TIME:20211105T164500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/52
DESCRIPTION:Title:
Mixed invariants in Khovanov homology for unorientable cobordisms\nby
Sucharit Sarkar (UCLA) as part of CRM - Séminaire du CIRGET / Géométrie
et Topologie\n\n\nAbstract\n** Note : the event will take place at 11.30
am and not 11 am as usual.\n** Attention : l'horaire est modifié à 11.30
exceptionnellement.\n\nUsing Bar-Natan's and Lee's deformations of Khovan
ov homology of links\, we define minus\, plus\, and infinity versions of K
hovanov homology. Given an unorientable cobordism in [0\,1]\\times S^3 fro
m a link L_0 to a link L_1\, we define a mixed invariant as a map from the
minus version of the Khovanov homology of L_0 to the plus version of the
Khovanov homology of L_1. The construction is similar to the mixed invaria
nt in Heegaard Floer homology. This invariant can be used to distinguish e
xotic cobordisms\, that is\, two cobordisms which are topologically isotop
ic but not smoothly isotopic. This is joint with Robert Lipshitz.\n
LOCATION:https://researchseminars.org/talk/CIRGET/52/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Adam Jacob (University of California Davis)
DTSTART;VALUE=DATE-TIME:20211217T160000Z
DTEND;VALUE=DATE-TIME:20211217T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/53
DESCRIPTION:Title:
Special Lagrangian torus fibrations on Del Pezzo and Rational Elliptic Sur
faces\nby Adam Jacob (University of California Davis) as part of CRM -
Séminaire du CIRGET / Géométrie et Topologie\n\n\nAbstract\nIn this ta
lk I will demonstrate the construction of mirror special Lagrangian torus
fibrations on two non-compact spaces: A Del Pezzo surface with a smooth an
ticanonical divisor removed\, and a rational elliptic surface minus a sing
ular fiber of Kodaira type I_k. Special emphasis will be given to local ge
ometric models\, and how the mean curvature flow provides a key step in th
e construction. This is joint work with T.C. Collins and Y.-S. Lin\n
LOCATION:https://researchseminars.org/talk/CIRGET/53/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Steven Sivek (Imperial College)
DTSTART;VALUE=DATE-TIME:20211203T160000Z
DTEND;VALUE=DATE-TIME:20211203T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/54
DESCRIPTION:by Steven Sivek (Imperial College) as part of CRM - Séminaire
du CIRGET / Géométrie et Topologie\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/CIRGET/54/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ethan Addison (Notre Dame Univ.)
DTSTART;VALUE=DATE-TIME:20220114T160000Z
DTEND;VALUE=DATE-TIME:20220114T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/55
DESCRIPTION:Title:
Generalizing Poincaré-Type Kähler Metrics\nby Ethan Addison (Notre D
ame Univ.) as part of CRM - Séminaire du CIRGET / Géométrie et Topologi
e\n\n\nAbstract\nPoincaré-type metrics are a type of complete cusp metric
defined on the complement of a complex hypersurface $X$ in an ambient man
ifold\, yet a result by Auvray shows that constant scalar curvature metric
s of Poincaré-type always split into a product of cscK metrics in each of
the ends\, inducing a cscK metric on $X$. We prove a result about \\emph{
gnarled} Poincaré-type metrics using holomorphic flows on $X$ to construc
t complete cscK metrics near the ends which are perturbations of cscK Poin
caré-type metrics\, even when the induced perturbed Kähler class on $X$
does not admit a cscK metric\, thus generalizing the initial flavor of met
ric to one with fewer restrictions.\n
LOCATION:https://researchseminars.org/talk/CIRGET/55/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Francesco Lin (Columbia Univ.)
DTSTART;VALUE=DATE-TIME:20220121T160000Z
DTEND;VALUE=DATE-TIME:20220121T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/56
DESCRIPTION:Title:
Closed geodesics and Frøyshov invariants of hyperbolic three-manifolds\nby Francesco Lin (Columbia Univ.) as part of CRM - Séminaire du CIRGET
/ Géométrie et Topologie\n\n\nAbstract\nFrøyshov invariants are subtle
numerical topological invariants of rational homology three-spheres deri
ved from gradings in monopole Floer homology. In this talk I will look at
their relation with invariants arising from hyperbolic geometry (such as
volumes and lengths of closed geodesics)\, using an odd version of the S
elberg trace formula and ideas from analytic number theory. In particular
\, for the class of minimal L-spaces\, I will describe an effective proc
edure to compute them taking as input explicit geometric data\, and show
for example how this can be used to determine all the Frøyshov invariant
s for the Seifert-Weber dodecahedral space. This is joint work with M. Li
pnowski (McGill).\n
LOCATION:https://researchseminars.org/talk/CIRGET/56/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Xi Sisi Shen (Columbia Univ.)
DTSTART;VALUE=DATE-TIME:20220128T160000Z
DTEND;VALUE=DATE-TIME:20220128T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/57
DESCRIPTION:Title:
A Chern-Calabi flow on Hermitian Manifolds\nby Xi Sisi Shen (Columbia
Univ.) as part of CRM - Séminaire du CIRGET / Géométrie et Topologie\n\
n\nAbstract\nWe discuss the existence problem of constant Chern scalar cur
vature metrics on a compact complex manifold and introduce a Hermitian ana
logue of the Calabi flow on compact complex manifolds with vanishing first
Bott-Chern class.\n
LOCATION:https://researchseminars.org/talk/CIRGET/57/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kyle Hayden (Columbia Univ.)
DTSTART;VALUE=DATE-TIME:20220211T160000Z
DTEND;VALUE=DATE-TIME:20220211T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/59
DESCRIPTION:Title:
Where are the complex curves in Khovanov homology?\nby Kyle Hayden (Co
lumbia Univ.) as part of CRM - Séminaire du CIRGET / Géométrie et Topol
ogie\n\n\nAbstract\nSince the advent of gauge theory\, many modern tools e
xhibit a close connection with complex curves and a heightened sensitivity
to objects from the complex realm. Surprisingly\, this is true even for K
hovanov homology\, whose construction is combinatorial rather than geometr
ic. I will discuss this in the context of joint work with Isaac Sundberg t
hat uses Khovanov homology to study knotted surfaces in 4-space\, especial
ly (compact pieces of) complex curves in the 4-ball.\n
LOCATION:https://researchseminars.org/talk/CIRGET/59/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ruiran Sun (UQAM)
DTSTART;VALUE=DATE-TIME:20220218T160000Z
DTEND;VALUE=DATE-TIME:20220218T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/60
DESCRIPTION:by Ruiran Sun (UQAM) as part of CRM - Séminaire du CIRGET / G
éométrie et Topologie\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/CIRGET/60/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Louis Ioos (Max Planck Institute\, Bonn)
DTSTART;VALUE=DATE-TIME:20220311T160000Z
DTEND;VALUE=DATE-TIME:20220311T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/61
DESCRIPTION:Title:
Quantization methods in the Yau-Tian-Donaldson program\nby Louis Ioos
(Max Planck Institute\, Bonn) as part of CRM - Séminaire du CIRGET / Géo
métrie et Topologie\n\n\nAbstract\nA celebrated conjecture of Yau states
that the existence of a Kähler metric\nwith constant scalar curvature on
a projective manifold should be equivalent to a purely\nalgebraic stabilit
y condition. Much progress has been done on this conjecture in the\npast d
ecades\, culminating in what is now called the Yau-Tian-Donaldson program.
\nIn this talk\, I will explain the key role played by quantization method
s in this program\,\nand how they can be improved using a semiclassical es
timate of the quantum noise of\nBerezin-Toeplitz quantization. This is par
tly based on joint works in collaboration with\nVictoria Kaminker\, Leonid
Polterovich and Dor Shmoish.\n
LOCATION:https://researchseminars.org/talk/CIRGET/61/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jacob Caudell (Boston College)
DTSTART;VALUE=DATE-TIME:20220225T160000Z
DTEND;VALUE=DATE-TIME:20220225T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/62
DESCRIPTION:Title:
Lens space surgeries\, lattices\, and the Poincaré homology sphere.\n
by Jacob Caudell (Boston College) as part of CRM - Séminaire du CIRGET /
Géométrie et Topologie\n\nAbstract: TBA\n\nMoser's classification of Deh
n surgeries on torus knots (1971) inspired a now fifty-years-old project t
o classify "exceptional" Dehn surgeries on knots in the three-sphere. A pr
ominent component of this project seeks to classify which knots admit surg
eries to the "simplest" non-trivial 3-manifolds--lens spaces. By combining
data from Floer homology and the theory of integer lattices into the noti
on of a changemaker lattice\, Greene (2010) solved the lens space realizat
ion problem: every lens space which may be realized as surgery on a knot i
n the three-sphere may be realized by a knot already known to surger to th
at lens space (i.e. a Berge knot). In this talk\, we present a survey of t
echniques in Dehn surgery and their applications\, introduce a lattice the
oretic construction in the spirit of Greene's changemaker lattices\, and d
iscuss applications to surgeries on knots in the Poincaré homology sphere
.\n
LOCATION:https://researchseminars.org/talk/CIRGET/62/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alan Reid (Rice University)
DTSTART;VALUE=DATE-TIME:20220401T150000Z
DTEND;VALUE=DATE-TIME:20220401T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/63
DESCRIPTION:Title:
Embedding and bounding geometrically rational homology 3-spheres\nby A
lan Reid (Rice University) as part of CRM - Séminaire du CIRGET / Géomé
trie et Topologie\n\n\nAbstract\nBordism properties of closed manifolds ha
ve been a classical and important topic in topology\; for example it is a
classical result of Rohklin that all closed orientable 3-manifolds bound a
compact 4-manifold. In the context of hyperbolic manifolds\, a natural g
eometric version of bordism is that of bounding geometrically: namely whet
her a connected closed orientable hyperbolic n-manifold M could arise as
the totally geodesic boundary of a compact hyperbolic (n+1)-manifold W. In
work with Long (from 2000) we showed that there are infinitely many clos
ed orientable hyperbolic n-manifolds that bound geometrically. One featu
re of our construction is that all examples produced in dimension 3 have
b_1>0. This led to the question of whether there are rational homology 3-
spheres that bound geometrically. In this talk we describe a construction
of infinitely many such rational homology 3-spheres.\n
LOCATION:https://researchseminars.org/talk/CIRGET/63/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Allison Moore (Virginia Commonwealth)
DTSTART;VALUE=DATE-TIME:20220408T150000Z
DTEND;VALUE=DATE-TIME:20220408T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/64
DESCRIPTION:Title:
Cosmetic surgery\, cosmetic crossings\nby Allison Moore (Virginia Comm
onwealth) as part of CRM - Séminaire du CIRGET / Géométrie et Topologie
\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/CIRGET/64/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexandre Girouard (Université de Laval)
DTSTART;VALUE=DATE-TIME:20220422T150000Z
DTEND;VALUE=DATE-TIME:20220422T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/65
DESCRIPTION:Title:
Steklov eigenvalues\, homogenization and free boundary minimal surfaces\nby Alexandre Girouard (Université de Laval) as part of CRM - Séminair
e du CIRGET / Géométrie et Topologie\n\n\nAbstract\nIt has been known si
nce classical antiquity that disks have the largest area among planar figu
res of prescribed perimeter. Nevertheless\, a rigorous proof was only give
n around the end of the 19th century. During the 20th century\, area and p
erimeter were replaced by many other analytic and geometric quantities\, a
nd the geometric setting has been vastly enlarged. In this talk we will be
interested in two such isoperimetric-type problems:\n\n(A) Free boundary
minimal surfaces\nThe minimization of area for surfaces in balls\, with th
eir boundary that are constrained to live on the boundary sphere (free bou
ndary minimal surfaces).\n\nB) Isoperimetric problem for Steklov eigenvalu
es\nThe maximization of the spectral gap of Dirichlet-to-Neumann operators
for surfaces with prescribed perimeter.\n\nFor domains in the unit sphere
and planar domains\, I will describe the complete solution of problem (B)
. It is based on the theory of homogenization by perforation\, a topic whi
ch comes from applied and industrial mathematics. Then\, using work of Fra
ser and Schoen\, I will show how this solution leads to the construction o
f new free boundary minimal surfaces in the unit 3-ball that have area lar
ger than was previously thought possible.\n\nThis talk is based on joint w
ork with Antoine Henrot\, Mikhail Karpukhin and Jean Lagacé.\n
LOCATION:https://researchseminars.org/talk/CIRGET/65/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jean-Philippe Burelle (Univ. de Sherbrooke)
DTSTART;VALUE=DATE-TIME:20220429T150000Z
DTEND;VALUE=DATE-TIME:20220429T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/66
DESCRIPTION:Title:
Piecewise circular curves and flag positivity.\nby Jean-Philippe Burel
le (Univ. de Sherbrooke) as part of CRM - Séminaire du CIRGET / Géométr
ie et Topologie\n\n\nAbstract\nIn this joint work with Ryan Kirk\, we inve
stigate moduli spaces of closed piecewise circular curves. A curve is piec
ewise circular if it is made of pieces which are circular arcs\, and these
arcs are tangent at the intersection of pieces. We identify a special con
nected component of these moduli spaces and prove that it is homeomorphic
to an open ball of dimension 2n-10. We characterize this component as the
subset of curves which have decreasing curvature in an appropriate sense.
The proof involves "Lie circle geometry"\, a somewhat out of fashion theor
y of the homogeneous spaces of Sp(4\,R)\, and Lusztig-Fock-Goncharov posit
ivity.\n
LOCATION:https://researchseminars.org/talk/CIRGET/66/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Joel Kamnitzer (University of Toronto)
DTSTART;VALUE=DATE-TIME:20220506T150000Z
DTEND;VALUE=DATE-TIME:20220506T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/67
DESCRIPTION:Title:
Symplectic duality and affine Grassmannian slices\nby Joel Kamnitzer (
University of Toronto) as part of CRM - Séminaire du CIRGET / Géométrie
et Topologie\n\n\nAbstract\nSymplectic resolutions are an exciting new fr
ontier of research in geometry and representation theory. One of the most
fascinating aspects of this study is symplectic duality: the observation
that these resolutions come in pairs with matching properties. The Coulom
b\nbranch construction allows us to produce and study many of these dual p
airs. I will attempt to survey recent work in this area\, particularly f
ocusing on ADE quiver varieties and affine Grassmannian slices.\n
LOCATION:https://researchseminars.org/talk/CIRGET/67/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aldo Witte (KU Leuven)
DTSTART;VALUE=DATE-TIME:20220527T150000Z
DTEND;VALUE=DATE-TIME:20220527T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/68
DESCRIPTION:Title:
Singular fibrations in toric and Poisson geometry\nby Aldo Witte (KU L
euven) as part of CRM - Séminaire du CIRGET / Géométrie et Topologie\n\
n\nAbstract\nIn this talk I will present a class of singular fibrations ca
lled boundary Lefschetz fibrations. These play important roles in the\, qu
ite different\, fields of semi-toric and generalized complex geometry. Aft
er describing how they can be studied using Lie algebroids\, I willshow th
at they behave well with respect to blow-ups and connected sums. Finally\,
I will show how they can be used in extending T-duality\, a version of mi
rror symmetry. Joint work with Gil Cavalcanti and Ralph Klaasse.\n
LOCATION:https://researchseminars.org/talk/CIRGET/68/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Eric Finster (University of Birmingham)
DTSTART;VALUE=DATE-TIME:20220902T150000Z
DTEND;VALUE=DATE-TIME:20220902T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/70
DESCRIPTION:Title:
Homotopy Theory and Constructive Mathematics\nby Eric Finster (Univers
ity of Birmingham) as part of CRM - Séminaire du CIRGET / Géométrie et
Topologie\n\n\nAbstract\nConstructive mathematicians and computer scientis
ts have long been\ninterested in logical theories in which all mathematica
l statements\nhave computational content. In such systems\, any proof of
the\nexistence of some natural number automatically gives an algorithm for
\ncomputing the number. Most modern computer "proof assistants"\, that\ni
s\, programs aimed at helping the user construct and verify the\ncorrectne
ss of mathematical statements\, are based on a class of such\nsystems call
*type theories*.\n\nAround 15 years ago\, however\, it was discovered tha
t the way type\ntheories represent equality meant that\, rather than descr
ibing\nconstructive *sets*\, these systems should more properly be thought
of\nas describing constructive *homotopy types*. This has led to a numbe
r\nof new connections between homotopy theory\, higher category theory\,\n
computer science and logic. In this talk\, I will describe some of\nthese
ideas and the results that they have led to.\n
LOCATION:https://researchseminars.org/talk/CIRGET/70/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ruiran Sun (CIRGET)
DTSTART;VALUE=DATE-TIME:20220923T150000Z
DTEND;VALUE=DATE-TIME:20220923T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/71
DESCRIPTION:Title:
On slope and valuative K-semistability for big and nef birational divisors
\nby Ruiran Sun (CIRGET) as part of CRM - Séminaire du CIRGET / Géom
étrie et Topologie\n\nLecture held in PK-5115.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/CIRGET/71/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mathieu Anel (Carnegie Mellon University)
DTSTART;VALUE=DATE-TIME:20220930T150000Z
DTEND;VALUE=DATE-TIME:20220930T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/72
DESCRIPTION:Title:
Introduction to non-separated topology\nby Mathieu Anel (Carnegie Mell
on University) as part of CRM - Séminaire du CIRGET / Géométrie et Topo
logie\n\nLecture held in PK-5115.\n\nAbstract\nClassically a topological s
pace has a set of points. But non-separated spaces (
Shrinking Kahler-Ricci solitons\nby Ronan Conlan (University of Texas
at Dallas) as part of CRM - Séminaire du CIRGET / Géométrie et Topologi
e\n\nLecture held in PK-5115.\n\nAbstract\nShrinking Kahler-Ricci solitons
model finite-time singularities of the Kahler-Ricci flow\, hence the need
for their classification. I will talk about the classification of such so
litons in 4 real dimensions. This is joint work with Bamler-Cifarelli-Deru
elle\, Cifarelli-Deruelle\, and Deruelle-Sun.\n
LOCATION:https://researchseminars.org/talk/CIRGET/73/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Carlo Scarpa (CIRGET)
DTSTART;VALUE=DATE-TIME:20221014T150000Z
DTEND;VALUE=DATE-TIME:20221014T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/74
DESCRIPTION:Title:
Scalar curvature and deformations of complex structures\nby Carlo Scar
pa (CIRGET) as part of CRM - Séminaire du CIRGET / Géométrie et Topolog
ie\n\nLecture held in PK-5115.\n\nAbstract\nA classical problem in Kähler
geometry is to choose\, among all the possible Kähler metrics on a manif
old\, a canonical representative of each Kähler class. This is usually do
ne by imposing curvature conditions on the metric\, such as Ricci-flat\, K
ähler-Einstein\, or constant scalar curvature. In this talk\, I will desc
ribe how the problem changes when we also consider deformations of the com
plex structure\, introducing a partial differential equation which gives a
canonical choice of a Kähler metric for each deformation class. Time per
mitting\, I will examine the case of toric manifolds in more detail. The t
alk is based on arxiv:2202.00429 and joint work with J. Stoppa.\n
LOCATION:https://researchseminars.org/talk/CIRGET/74/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Georg Biedermann (Universidad del Norte)
DTSTART;VALUE=DATE-TIME:20221021T150000Z
DTEND;VALUE=DATE-TIME:20221021T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/75
DESCRIPTION:Title:
Calculus in homotopy theory\nby Georg Biedermann (Universidad del Nort
e) as part of CRM - Séminaire du CIRGET / Géométrie et Topologie\n\nLec
ture held in PK-5115.\n\nAbstract\n(joint with M. Anel\, E. Finster and A.
Joyal)\nIn classical calculus one studies smooth functions via their Tayl
or series. Its $n$-th homogeneous layer is governed by a single coefficien
t: the $n$-th derivative. As part of his effort to relate algebraic K-theo
ry to topological cyclic homology Goodwillie during the 90s introduced "Go
odwillie calculus" to homotopy theory. A homotopy invariant functor is vie
wed as an analogue of a smooth function and resolved into a tower whose $n
$-th homogeneous layer is governed by a single coefficient: a spectrum (in
the sense of homotopy theory) with $\\Sigma_n$-action. Goodwillie calculu
s is now a central tool in homotopy theory.\nAround the same time (and inf
luenced by Goodwillie) Michael Weiss constructed "orthogonal calculus": sp
ace-valued functors from the category of finite dimensional Euclidean vect
or spaces with morphism given by Stiefel manifolds are resolved into an or
thogonal tower whose $n$-th homogeneous layer is governed by a spectrum wi
th an action by $O(n)$. Weiss' theory has found many applications in diffe
rential topology.\nPeople have wondered for a long time whether both theor
ies have a common description. We can give one. In fact\, it turns out tha
t the theory of $\\infty$-topoi is the perfect language. For any left exac
t localization $L$ of an $\\infty$-topos we construct a tower $(P_n)_{n\\g
e 0}$ of left exact localizations such that $P_0=L$. The pointed objects o
f the layers form stable $\\infty$-categories. The tower is analogous to t
he completion tower of a commutative ring with respect to an ideal. It spe
cializes to Goodwillie's and Weiss' tower.\n\nI am going to tell you a bit
about all these towers.\n
LOCATION:https://researchseminars.org/talk/CIRGET/75/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Clara Aldana (Universidad del Norte)
DTSTART;VALUE=DATE-TIME:20221028T150000Z
DTEND;VALUE=DATE-TIME:20221028T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/76
DESCRIPTION:Title:
Polyakov Formulas for conical singularities in two dimensions.\nby Cla
ra Aldana (Universidad del Norte) as part of CRM - Séminaire du CIRGET /
Géométrie et Topologie\n\nLecture held in PK-5115.\n\nAbstract\nIn the f
irst part of the talk I will introduce the regularized determinant of the
Laplace operator on a Riemannian manifold and will explain the context and
the motivation to consider Polyakov's formulas. Then\, I will present the
formula for surfaces with conical singularities and smooth conformal fact
ors\, and for polygonal domains in a Riemannian surface. I will mention ho
w we obtain the so-called variational Polyakov formula for cones and secto
rs and how in these cases we can obtain closed formulas for the determinan
t of the Laplacian. The results presented in this talk are joint work with
Klaus Kirsten and Julie Rowlett\, arxiv.org/abs/2010.02776.\n
LOCATION:https://researchseminars.org/talk/CIRGET/76/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Manh Tien Nguyen (Oxford University)
DTSTART;VALUE=DATE-TIME:20221104T150000Z
DTEND;VALUE=DATE-TIME:20221104T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/77
DESCRIPTION:Title:
Monotonicity theorems and how to compare them\nby Manh Tien Nguyen (Ox
ford University) as part of CRM - Séminaire du CIRGET / Géométrie et To
pologie\n\nLecture held in PK-5115.\n\nAbstract\nI will present two result
s. The first one concerns minimal surfaces of the hyperbolic space and is
a relation between their renormalised area (in the sense of Graham and Wit
ten) and the length of their ideal boundary measured in different metrics
of the conformal infinity. The second result concerns minimal submanifolds
of the sphere and is a relation between their volume and antipodal-ness.
Both results were obtained from the same framework\, which involves new mo
notonicity theorems and a comparison principle for them.\n
LOCATION:https://researchseminars.org/talk/CIRGET/77/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Takahiro Aoi (Abuno high school)
DTSTART;VALUE=DATE-TIME:20221111T160000Z
DTEND;VALUE=DATE-TIME:20221111T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/78
DESCRIPTION:Title:
A conical approximation of constant scalar curvature K\\”{a}hler metrics
of Poincar\\’{e} type and log K-semistability\nby Takahiro Aoi (Abu
no high school) as part of CRM - Séminaire du CIRGET / Géométrie et Top
ologie\n\nLecture held in PK-5115.\n\nAbstract\nGuenancia proved that a K\
\”{a}hler-Einstein metric of Poincar\\’{e} type is the limit of a sequ
ence of K\\”{a}hler-Einstein metrics with cone singularities along a smo
oth divisor. In this talk\, I will explain the recent result which is an a
nalogue of Guenancia’s result for constant scalar curvature K\\”{a}hle
r metrics. In addition\, I will explain that constant scalar curvature K\\
”{a}hler metrics of Poincar\\’{e} type implies log K-semistability wit
h angle 0.\n\nNote that the talk will take place in Boyer room PK-5675\n
LOCATION:https://researchseminars.org/talk/CIRGET/78/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Viktor Kalvin (Dawson College and Concordia Univ.)
DTSTART;VALUE=DATE-TIME:20221118T160000Z
DTEND;VALUE=DATE-TIME:20221118T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/79
DESCRIPTION:Title:
Determinants of Laplacians on compact surfaces with conical singularities<
/a>\nby Viktor Kalvin (Dawson College and Concordia Univ.) as part of CRM
- Séminaire du CIRGET / Géométrie et Topologie\n\nLecture held in PK-51
15.\n\nAbstract\nIn this talk I will discuss new anomaly formulae for the
zeta regularized spectral determinants of Laplacians on compact Riemann su
rfaces. These formulae are valid for the metrics with conical singularitie
s and\, in particular\, show how the determinants of Laplacians depend on
the orders (angles) of conical singularities. With a simple example I wil
l show that the extremal properties of the determinants of Laplacians on s
ingular metrics are very different from the classical results of Osgood\,
Phillips\, and Sarnak for the smooth metrics. If time permits\, I will als
o discuss how this is related to Kaehler potentials of metrics on moduli s
paces\, the famous accessory parameters\, and the celebrated DOZZ formula
from the Liouville conformal field theory. The talk is based on a series o
f recent papers of mine.\n
LOCATION:https://researchseminars.org/talk/CIRGET/79/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marcin Sroka (CIRGET)
DTSTART;VALUE=DATE-TIME:20221125T160000Z
DTEND;VALUE=DATE-TIME:20221125T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/80
DESCRIPTION:Title:
Monge-Ampere equation in hypercomplex geometry\nby Marcin Sroka (CIRGE
T) as part of CRM - Séminaire du CIRGET / Géométrie et Topologie\n\nLec
ture held in PK-5115.\n\nAbstract\nI will outline the state of art concern
ing the solvability of the so called quaternionic Monge-Ampere equation. T
his second order\, elliptic\, nonlinear PDE was introduced by Alesker and
Verbisty as a device for confirming the version of Calabi conjecture on hy
percomplex manifolds. Its solvability has applications also for obtaining
Calabi-Yau type theorems\nfor some classes of hermitian and hyperhermitian
metrics.\n
LOCATION:https://researchseminars.org/talk/CIRGET/80/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sally Collins (Georgia Tech)
DTSTART;VALUE=DATE-TIME:20221209T160000Z
DTEND;VALUE=DATE-TIME:20221209T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/81
DESCRIPTION:Title:
Homology cobordism and knot concordance\nby Sally Collins (Georgia Tec
h) as part of CRM - Séminaire du CIRGET / Géométrie et Topologie\n\nLec
ture held in PK-5115.\n\nAbstract\nThe 0-surgeries of two knots K1 and K2
are homology cobordant rel meridians if there exists an integer homology c
obordism X between them such that the two positive knot meridians are in t
he same homology class of X. It is a natural question to ask: if two knots
have the “same” 0-surgeries in this sense\, must they be smoothly con
cordant? We give a pair of rationally slice knots as counterexample\, with
one of concordance order two and the other of infinite order\, and along
the way expand upon a Floer homology technique for obstructing torsion in
the smooth concordance group first introduced by Hom\, Kang\, Park\, and S
toffregen.\n
LOCATION:https://researchseminars.org/talk/CIRGET/81/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Paula Truöl (ETH Zurich)
DTSTART;VALUE=DATE-TIME:20221216T160000Z
DTEND;VALUE=DATE-TIME:20221216T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/82
DESCRIPTION:Title:
Strongly quasipositive knots are concordant to infinitely many strongly qu
asipositive knots\nby Paula Truöl (ETH Zurich) as part of CRM - Sémi
naire du CIRGET / Géométrie et Topologie\n\nLecture held in PK-5115.\n\n
Abstract\nKnots are smooth embeddings of the (oriented) circle S^1 into th
e 3-sphere S^3\, usually studied up to an equivalence relation called ambi
ent isotopy. A natural generalization in dimension 4 of the question wheth
er certain knots are isotopic to the trivial knot is the concept of concor
dance\, another equivalence relation on the set of knots.\nWe show that ev
ery non-trivial strongly quasipositive knot is (smoothly) concordant to in
finitely many pairwise non-isotopic strongly quasipositive knots. In contr
ast to our result\, it was conjectured by Baker that concordant strongly q
uasipositive fibered knots are isotopic. Our construction uses a satellite
operation whose companion is a slice knot with maximal Thurston-Bennequin
number -1.\nIn the talk\, we will define the relevant terms necessary to
understand the theorem in the title\, and explain the context of this resu
lt. If time permits\, we will say a few words about how the construction e
xtends to links.\n
LOCATION:https://researchseminars.org/talk/CIRGET/82/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kaya Ferendo (Kaya Ferendo)
DTSTART;VALUE=DATE-TIME:20221212T160000Z
DTEND;VALUE=DATE-TIME:20221212T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/83
DESCRIPTION:Title:
FI-calculus and representation stability\nby Kaya Ferendo (Kaya Ferend
o) as part of CRM - Séminaire du CIRGET / Géométrie et Topologie\n\nLec
ture held in PK-5115.\n\nAbstract\nFI is the category of finite sets and i
njections. Representation stability is an appealing phenomenon enjoyed by
certain functors from FI to\, for example\, rational vector spaces. The ra
tional cohomology of certain families of moduli spaces is a key example. F
unctor calculus is a family of techniques and structures that are useful i
n the study of functors between certain infinity-categories. In this talk\
, we'll see that representation stability emerges as a facet of a new kind
of functor calculus and discuss some of the features of this functor calc
ulus.\n
LOCATION:https://researchseminars.org/talk/CIRGET/83/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shih-Kai Chiu (Oxford University)
DTSTART;VALUE=DATE-TIME:20230127T160000Z
DTEND;VALUE=DATE-TIME:20230127T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/84
DESCRIPTION:Title:
Calabi-Yau manifolds with maximal volume growth\nby Shih-Kai Chiu (Oxf
ord University) as part of CRM - Séminaire du CIRGET / Géométrie et Top
ologie\n\nLecture held in PK-5115.\n\nAbstract\nCalabi-Yau manifolds with
maximal volume growth are complete Ricci-flat Kähler manifolds where any
r-ball has volume at least r^m up to a uniform constant factor and m is th
e real dimension of the manifold. Bishop-Gromov volume comparison theorem
implies that such growth is indeed maximal. This notion generalizes the mo
re well-known notion of asymptotically conical (AC) manifolds. Contrary to
the AC case\, the asymptotic cones at infinity in general can have\nnon-i
solated singularities. In this talk\, I will give a (biased) survey of the
recent progress on this ongoing topic.\n
LOCATION:https://researchseminars.org/talk/CIRGET/84/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yueqiao Wu (Michigan Univ)
DTSTART;VALUE=DATE-TIME:20230120T160000Z
DTEND;VALUE=DATE-TIME:20230120T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/85
DESCRIPTION:Title:
A non-Archimedean characterization of local K-stability\nby Yueqiao Wu
(Michigan Univ) as part of CRM - Séminaire du CIRGET / Géométrie et To
pologie\n\nLecture held in PK-5115.\n\nAbstract\nLog Fano cone singulariti
es are generalizations of cones over Fano varieties\, and have a local K-s
tability theory extending the one for Fano varieties. In this talk\, we ai
m to give a characterization for local K-stability from a non-Archimedean
point of view. As a consequence of this characterization\, we can show tha
t a log Fano cone singularity is K-polystable with respect to a larger cla
ss of test configurations if it admits a Ricci-flat Kähler cone metric\,
strengthening earlier results of Collins-Székelyhidi and Li.\n
LOCATION:https://researchseminars.org/talk/CIRGET/85/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nicholas McCleerey (Michigan Univ)
DTSTART;VALUE=DATE-TIME:20230203T160000Z
DTEND;VALUE=DATE-TIME:20230203T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/86
DESCRIPTION:by Nicholas McCleerey (Michigan Univ) as part of CRM - Sémina
ire du CIRGET / Géométrie et Topologie\n\nLecture held in PK-5115.\nAbst
ract: TBA\n
LOCATION:https://researchseminars.org/talk/CIRGET/86/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tristan Ozuch (MIT)
DTSTART;VALUE=DATE-TIME:20230324T150000Z
DTEND;VALUE=DATE-TIME:20230324T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/88
DESCRIPTION:Title:
4-dimensional specific aspects of Ricci flows\nby Tristan Ozuch (MIT)
as part of CRM - Séminaire du CIRGET / Géométrie et Topologie\n\nLectur
e held in PK-5115.\n\nAbstract\nRicci flow has been extensively studied\,
and most results are either true only in dimension 3 or hold in every dime
nsion. However\, given the potential topological applications\, a theory s
pecific to the 4-dimensional situation is desirable. In this discussion\,
I will present tools and techniques that are unique to the 4-dimensional c
ase.\n\nTogether with A. Deruelle\, we introduce a notion of stability for
orbifold singularities. This notion helps to explain the formation of orb
ifold singularities along Ricci flow. Moreover\, in collaboration with K.
Naff\, we utilize self-duality in dimension 4 to simplify the evolution eq
uations of curvature. This approach lets us uncover intriguing connections
between Ricci flow and Yang-Mills flow.\n
LOCATION:https://researchseminars.org/talk/CIRGET/88/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nathan Grieve (Carleton University)
DTSTART;VALUE=DATE-TIME:20230224T160000Z
DTEND;VALUE=DATE-TIME:20230224T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/89
DESCRIPTION:Title:
On Harder-Narasimhan data and the Central Limit Theorem\nby Nathan Gri
eve (Carleton University) as part of CRM - Séminaire du CIRGET / Géomét
rie et Topologie\n\nLecture held in PK-5115.\n\nAbstract\nStarting with th
e work of Harder and Narasimhan\, the concept of canonical (Harder and Nar
asimhan) filtration emerged as a fundamental tool for measuring the extent
to which a given object in a suitable category fails to be slope semistab
le. In this lecture\, I will discuss an abstract concept of Harder and Na
rasimhan data which I formulated as a tool for expanding on the key techni
cal techniques of Codogni and Patakfalvi\, which arise in their work on we
ak positivity of the CM line bundle over the moduli stack of K-semistable
Fano varieties. Another source of motivation is Grayson's lattice reducti
on theory via slope semistability. Finally\, via theory of Faltings and W
ustholz\, for slope semistabilty of filtered vector spaces\, there is a st
rong overlap with techniques from Diophantine approximation for linear ser
ies. As application of this circle of ideas\, I will explain a recent res
ult which gives a filtered vector space analogue to the above mentioned ke
y technical result of Codogni and Patakfalvi.\n
LOCATION:https://researchseminars.org/talk/CIRGET/89/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Maxence Mayrand (Sherbrooke University)
DTSTART;VALUE=DATE-TIME:20230310T160000Z
DTEND;VALUE=DATE-TIME:20230310T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/90
DESCRIPTION:Title:
Hyperkähler metrics via deformation theory\nby Maxence Mayrand (Sherb
rooke University) as part of CRM - Séminaire du CIRGET / Géométrie et T
opologie\n\nLecture held in PK-5115.\n\nAbstract\nHyperkähler structures
are special holonomy metrics with a particularly rich geometry. I will dis
cuss methods for constructing such metrics\, and the weaker notion of hype
rcomplex structures\, using the theory of deformation of complex structure
s. As a consequence\, we obtain new hyperkähler metrics on certain Lie gr
oupoids\, namely\, integrations of holomorphic Poisson surfaces\, by using
results on the deformation theory of such surfaces.\n
LOCATION:https://researchseminars.org/talk/CIRGET/90/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Emily Cliff (Sherbrooke University)
DTSTART;VALUE=DATE-TIME:20230421T140000Z
DTEND;VALUE=DATE-TIME:20230421T150000Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/91
DESCRIPTION:Title:
Smooth 2-groups and their principal bundles\nby Emily Cliff (Sherbrook
e University) as part of CRM - Séminaire du CIRGET / Géométrie et Topol
ogie\n\nLecture held in PK-5115.\n\nAbstract\nA 2-group is a categorical g
eneralization of a group: it's a category with a multiplication operation
which satisfies the usual group axioms only up to coherent isomorphisms. I
n this talk I will introduce the category of Lie groupoids and bibundles b
etween them\, in order to provide the definition of a smooth 2-group. I wi
ll define principal bundles for such a smooth 2-group\, and provide classi
fication results that allow us to compare them to principal bundles for or
dinary groups. As a consequence in specific settings\, we obtain a categor
ification of the Freed--Quinn line bundle over the moduli stack Bun_G(X) f
or a finite group G and Riemann surface X. This is a line bundle which pla
ys an important role in Dijkgraaf--Witten theory (i.e. Chern--Simons theo
ry for the finite group G). This talk is based on joint work with Dan Berw
ick-Evans\, Laura Murray\, Apurva Nakade\, and Emma Phillips. I will not a
ssume any previous background on 2-groups\, Lie groupoids\, or Dijkgraaf--
Witten theory.\n\nNote that we have 2 talks this week\, one at 10 am (E. C
liff)\, another one at 11 am (A. Adem).\n
LOCATION:https://researchseminars.org/talk/CIRGET/91/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Maxime Fortier Bourque (Université de Montréal)
DTSTART;VALUE=DATE-TIME:20230217T160000Z
DTEND;VALUE=DATE-TIME:20230217T171500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/92
DESCRIPTION:Title:
The systole of hyperbolic surfaces\nby Maxime Fortier Bourque (Univers
ité de Montréal) as part of CRM - Séminaire du CIRGET / Géométrie et
Topologie\n\nLecture held in PK-5115.\n\nAbstract\nThe systole of a Rieman
nian manifold is defined as the infimal length of its closed geodesics tha
t are not contractible and was studied by Berger and Gromov in the 70's an
d 80's. In this talk\, I will survey recent results on the systole of clos
ed hyperbolic surfaces. In particular\, I will explain how to construct a
surface out of polygons glued along a graph in a way that we can determine
its systole. Variants of this construction yield numerous local maxima fo
r the systole\, critical points of lower index than expected\, and are use
d to prove that the dimension of a certain set defined by Thurston is larg
er than hoped.\n
LOCATION:https://researchseminars.org/talk/CIRGET/92/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Panagiotis Dimakis (Stanford University)
DTSTART;VALUE=DATE-TIME:20230317T150000Z
DTEND;VALUE=DATE-TIME:20230317T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/93
DESCRIPTION:Title:
BAA branes on the Hitchin moduli space from solutions to the extended Bogo
molny equations\nby Panagiotis Dimakis (Stanford University) as part o
f CRM - Séminaire du CIRGET / Géométrie et Topologie\n\nLecture held in
PK-5115.\n\nAbstract\nBAA branes are complex Lagrangian submanifolds of t
he Hitchin space. Recently\, there has been interest in these objects due
to their appearance in mirror symmetry conjectures and due to their intima
te connection with the geometry of the Hitchin space. In this talk I will
introduce the above notions. Then I will introduce the extended Bogomolny
equations and explain how their solutions lead to holomorphic data associa
ted with a Riemann surface. As long as the degree of a naturally occuring
line bundle is not too negative\, I will show that the moduli of these hol
omorphic data is a BAA brane. Some of the BAA branes obtained this way are
known but some are new.\n
LOCATION:https://researchseminars.org/talk/CIRGET/93/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mihai Paun (Universitat Bayreuth)
DTSTART;VALUE=DATE-TIME:20230331T150000Z
DTEND;VALUE=DATE-TIME:20230331T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/94
DESCRIPTION:Title:
Infinitesimal extension of pluricanonical forms and injectivity.\nby M
ihai Paun (Universitat Bayreuth) as part of CRM - Séminaire du CIRGET / G
éométrie et Topologie\n\nLecture held in PK-5115.\n\nAbstract\nWe will p
resent some of the main results obtained in collaboration with J. Cao in t
he preprint arXiv:2012.05063.\n
LOCATION:https://researchseminars.org/talk/CIRGET/94/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fraser Binns (Boston College)
DTSTART;VALUE=DATE-TIME:20230414T150000Z
DTEND;VALUE=DATE-TIME:20230414T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/95
DESCRIPTION:Title:
Almost L-space knots\nby Fraser Binns (Boston College) as part of CRM
- Séminaire du CIRGET / Géométrie et Topologie\n\nLecture held in PK-51
15.\n\nAbstract\nHeegaard Floer homology is a powerful package of invarian
ts in low dimensional topology due originally to Ozsváth-Szabó. An L-spa
ce knot is a knot admitting surgeries to a manifold with Heegaard Floer ho
mology of minimal rank. Ozsváth-Szabó classified the knot Floer homology
of L-space knots from which it follows that L-space knots satisfy various
strong topological conditions. I will discuss a generalization of Ozsvát
h-Szabó's result to "almost L-space knots"\; i.e. knots which admit surge
ries to manifolds with Heegaard Floer homology of next to minimal rank.\n
LOCATION:https://researchseminars.org/talk/CIRGET/95/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alejandro Adem (University of British Columbia)
DTSTART;VALUE=DATE-TIME:20230421T150000Z
DTEND;VALUE=DATE-TIME:20230421T160000Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/96
DESCRIPTION:Title:
Minimal Euler Characteristics for Even-Dimensional Manifolds with Finite F
undamental Group\nby Alejandro Adem (University of British Columbia) a
s part of CRM - Séminaire du CIRGET / Géométrie et Topologie\n\nLecture
held in PK-5115.\n\nAbstract\nIn this talk we will discuss estimates for
the minimal Euler characteristic of even dimensional manifolds with a give
n finite fundamental group and a highly connected universal cover. In part
icular we strengthen the Hausmann-Weinberger invariants and extend them to
higher dimensions. As an application we obtain new restrictions for non-a
belian finite groups arising as fundamental groups of rational homology 4
–spheres. This is joint work with Ian Hambleton.\n\nNote that we have 2
talks this week\, one at 10 am (E. Cliff)\, another one at 11 am (A. Adem)
.\n
LOCATION:https://researchseminars.org/talk/CIRGET/96/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Xiaojun Wu (Universität Bayreuth)
DTSTART;VALUE=DATE-TIME:20230428T150000Z
DTEND;VALUE=DATE-TIME:20230428T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/97
DESCRIPTION:Title:
Compact K\\"ahler threefold with nef anticanonical line bundle\nby Xia
ojun Wu (Universität Bayreuth) as part of CRM - Séminaire du CIRGET / G
éométrie et Topologie\n\nLecture held in PK-5115.\n\nAbstract\nIn my tal
k\, I will discuss a recent collaboration with Shin-ichi Matsumura on comp
act Kähler threefolds with nef anticanonical line bundles. Thanks to the
breakthrough result of Cao-Höring\, we can focus on the non-projective ca
se. Using the Kähler threefold MMP developed by Höring-Peternell\, we ha
ve shown that there are only three possibilities for such manifolds: (1) C
alabi-Yau manifolds\; (2) projectivizations of numerical flat vector bundl
es over a torus\; (3) products of K3 surfaces with projective lines. I wil
l begin by reviewing the arguments of Cao-Höring and then explain the dif
ferent ingredients we used to establish our results in the Kähler setting
.\n
LOCATION:https://researchseminars.org/talk/CIRGET/97/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Simon Jubert (UQAM & Université de Toulouse)
DTSTART;VALUE=DATE-TIME:20230512T150000Z
DTEND;VALUE=DATE-TIME:20230512T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/98
DESCRIPTION:Title:
A Yau-Tian-Donaldson correspondence on a class of toric fibrations\nby
Simon Jubert (UQAM & Université de Toulouse) as part of CRM - Séminaire
du CIRGET / Géométrie et Topologie\n\nLecture held in PK-5115.\n\nAbstr
act\nThe Yau--Tian--Donaldson conjecture predicts that the existence of an
\nextremal metric (in the sense of Calabi) in a given Kähler class of\nK
ähler manifold is equivalent to a certain algebro-geometric notion of\nst
ability of this class. In this talk\, we will discuss a resolution of\nthi
s conjecture for a certain type of toric fibrations\, called\nsemisimple p
rincipal toric fibrations. One of the main assets of these\nfibrations is
that they come equipped with a connection which allows\ndefining\, from an
y Kähler metrics on the toric fiber X\, a Kähler\nmetric on the total sp
ace Y. After an introduction to the Calabi\nProblem for general compact K
ähler manifolds\, we will focus on the\nweighted toric setting. Then\, I
will explain how to translate the\nCalabi problem on Y\, to a weighted csc
K problem on the corresponding\ntoric fiber X (arxiv paper: arXiv:2108.12
297).\n
LOCATION:https://researchseminars.org/talk/CIRGET/98/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yoshinori Hashimoto (Osaka Metropolitan Univ)
DTSTART;VALUE=DATE-TIME:20230505T150000Z
DTEND;VALUE=DATE-TIME:20230505T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/99
DESCRIPTION:Title:
Uniform Hörmander estimates for flat nontrivial line bundles\nby Yosh
inori Hashimoto (Osaka Metropolitan Univ) as part of CRM - Séminaire du C
IRGET / Géométrie et Topologie\n\nLecture held in PK-5115.\n\nAbstract\n
Hörmander’s $L^2$-estimates for the $\\bar{\\partial}$ operators on hol
omorphic line bundles are of fundamental importance in complex analytic ge
ometry\, whose conventional proof crucially relies on the positivity of th
e line bundle. In this talk\, we prove the $L^2$-estimates for the solutio
ns to the $\\bar{\\partial}$ equation that hold uniformly for all flat non
trivial line bundles on compact Kähler manifolds\, whose main feature is
the quantitative description of the blow-up behaviour as the line bundle a
pproaches the trivial one. A key ingredient in the proof is the observatio
n that line bundles with vanishing first Chern classes are topologically t
rivial and can be identified with the trivial bundle with the "perturbed"
$\\bar{\\partial}$ operator which we define in terms of coordinates on the
Picard variety. This is a joint work with Takayuki Koike.\n
LOCATION:https://researchseminars.org/talk/CIRGET/99/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniel Litt (University of Toronto)
DTSTART;VALUE=DATE-TIME:20230915T150000Z
DTEND;VALUE=DATE-TIME:20230915T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/100
DESCRIPTION:Title: Hodge theory\, braid groups\, and some questions about 2x2 matrices\n
by Daniel Litt (University of Toronto) as part of CRM - Séminaire du CIRG
ET / Géométrie et Topologie\n\nLecture held in PK-5115.\n\nAbstract\nLet
$X_n$ be the set of conjugacy classes of n-tuples of 2x2 matrices whose p
roduct is the identity matrix--equivalently\, the character variety of a n
-punctured sphere. There is a natural braid group action on $X_n$\, whose
study goes back to work of Markoff in the late 19th century. The most basi
c question one can ask about this action\, which dates to work of Painlev
é\, Fuchs\, Schlesinger\, and Garnier in the beginning of the 20th centur
y\, is: what are the finite orbits? I'll explain the history of this quest
ion\, as well as some recent work\, joint with Lam and Landesman\, in whic
h we give a complete classification of such finite orbits\, by algebro-geo
metric methods\, when at least one of the matrices in question has infinit
e order.\n
LOCATION:https://researchseminars.org/talk/CIRGET/100/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Masafumi Hattori (Kyoto University)
DTSTART;VALUE=DATE-TIME:20230922T150000Z
DTEND;VALUE=DATE-TIME:20230922T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/101
DESCRIPTION:Title: K-stability of CY fibrations over curves\nby Masafumi Hattori (Kyoto
University) as part of CRM - Séminaire du CIRGET / Géométrie et Topolog
ie\n\nLecture held in PK-5115.\n\nAbstract\nIn K-stability\, the character
ization of K-stable varieties is well-studied when $K_X$ is ample or X is
a Calabi-Yau or Fano variety. However\, K-stability of Fano fibrations or
Calabi-Yau fibrations (i.e.\, $K_X$ is relatively trivial) is not known mu
ch in algebraic geometry. On the other hand\, cscK problems on fibrations
are studied by Fine\, Jian-Shi-Song and Dervan-Sektnan in Kahler geometry.
We introduce adiabatic K-stability (If $f:(X\,H)\\to (B\,L)$ is a fibrati
on of polarized varieties\, this means that K-stability of $(X\,aH+L)$ for
sufficiently small a) and show that adiabatic K-semistability of Calabi-Y
au fibration implies log-twisted K-semistability of the base variety by ap
plying the canonical bundle formula and the result on J-stability. If the
base is a curve\, we also obtain a partial converse. In this talk\, I woul
d like to explain our main results.\n
LOCATION:https://researchseminars.org/talk/CIRGET/101/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Tian-Jun Li (University of Minnesota)
DTSTART;VALUE=DATE-TIME:20230928T173000Z
DTEND;VALUE=DATE-TIME:20230928T183000Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/102
DESCRIPTION:Title: Uniruled symplectic surfaces\nby Tian-Jun Li (University of Minnesota
) as part of CRM - Séminaire du CIRGET / Géométrie et Topologie\n\nInte
ractive livestream: https://uqam.zoom.us/j/98999725241\nView-only livestre
am: https://www.youtube.com/channel/UCLkFm-uEvXSf9y-iQtWOLWA\nLecture held
in PK-5675.\n\nAbstract\nWe survey several aspects of the geometry of uni
ruled symplectic surfaces.\n\nRoom PK-5675\n
LOCATION:https://researchseminars.org/talk/CIRGET/102/
URL:https://uqam.zoom.us/j/98999725241
URL:https://www.youtube.com/channel/UCLkFm-uEvXSf9y-iQtWOLWA
END:VEVENT
BEGIN:VEVENT
SUMMARY:Claude Lebrun (Stony Brook)
DTSTART;VALUE=DATE-TIME:20231006T150000Z
DTEND;VALUE=DATE-TIME:20231006T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/103
DESCRIPTION:Title: Gravitational Instantons\, Weyl Curvature\, and Conformally Kahler Geomet
ry\nby Claude Lebrun (Stony Brook) as part of CRM - Séminaire du CIRG
ET / Géométrie et Topologie\n\nInteractive livestream: https://uqam.zoom
.us/j/98999725241\nView-only livestream: https://www.youtube.com/channel/U
CLkFm-uEvXSf9y-iQtWOLWA\nLecture held in PK-5115.\n\nAbstract\nThis talk w
ill describe my recent joint work with Olivier Biquard and Paul Gauduchon
on ALF Ricci-flat Riemannian 4-manifolds that are not hyper-Kahler. Our ma
in result largely characterizes the known solutions in terms of an open\,
purely Riemannian curvature condition.\n\nWe will have two seminars on the
6th of October ! \n11 am : Claude Lebrun\n 2 pm : Simone Gutt\n
LOCATION:https://researchseminars.org/talk/CIRGET/103/
URL:https://uqam.zoom.us/j/98999725241
URL:https://www.youtube.com/channel/UCLkFm-uEvXSf9y-iQtWOLWA
END:VEVENT
BEGIN:VEVENT
SUMMARY:Simone Gutt (Université Libre de Bruxelles)
DTSTART;VALUE=DATE-TIME:20231006T180000Z
DTEND;VALUE=DATE-TIME:20231006T191500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/104
DESCRIPTION:Title: Around almost complex structures\nby Simone Gutt (Université Libre d
e Bruxelles) as part of CRM - Séminaire du CIRGET / Géométrie et Topolo
gie\n\nInteractive livestream: https://uqam.zoom.us/j/98999725241\nView-on
ly livestream: https://www.youtube.com/channel/UCLkFm-uEvXSf9y-iQtWOLWA\nL
ecture held in PK-5115.\n\nAbstract\nSmooth almost complex structures on m
anifolds (in particular on symplectic manifolds) have various integrabilit
y properties.\nWe have been interested in defining relevant properties wh
ich a non integrable almost complex structure may have\, in terms of its N
ijenhuis tensor.\nIn particular\, we define the notions of minimally or ma
ximally non integrable almost complex structures\, and the notion of trans
verse complex structure defined by an almost complex structure.\nWe review
some Dolbeault-type cohomologies associated to an almost complex structur
e.\n
LOCATION:https://researchseminars.org/talk/CIRGET/104/
URL:https://uqam.zoom.us/j/98999725241
URL:https://www.youtube.com/channel/UCLkFm-uEvXSf9y-iQtWOLWA
END:VEVENT
BEGIN:VEVENT
SUMMARY:Thomas Barthelmé
DTSTART;VALUE=DATE-TIME:20231013T150000Z
DTEND;VALUE=DATE-TIME:20231013T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/105
DESCRIPTION:by Thomas Barthelmé as part of CRM - Séminaire du CIRGET / G
éométrie et Topologie\n\nInteractive livestream: https://uqam.zoom.us/j/
98999725241\nView-only livestream: https://www.youtube.com/channel/UCLkFm-
uEvXSf9y-iQtWOLWA\nLecture held in PK-5115.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/CIRGET/105/
URL:https://uqam.zoom.us/j/98999725241
URL:https://www.youtube.com/channel/UCLkFm-uEvXSf9y-iQtWOLWA
END:VEVENT
BEGIN:VEVENT
SUMMARY:Abdellah Lahdili
DTSTART;VALUE=DATE-TIME:20231020T150000Z
DTEND;VALUE=DATE-TIME:20231020T161500Z
DTSTAMP;VALUE=DATE-TIME:20230925T232503Z
UID:CIRGET/106
DESCRIPTION:by Abdellah Lahdili as part of CRM - Séminaire du CIRGET / G
éométrie et Topologie\n\nInteractive livestream: https://uqam.zoom.us/j/
98999725241\nView-only livestream: https://www.youtube.com/channel/UCLkFm-
uEvXSf9y-iQtWOLWA\nLecture held in PK-5115.\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/CIRGET/106/
URL:https://uqam.zoom.us/j/98999725241
URL:https://www.youtube.com/channel/UCLkFm-uEvXSf9y-iQtWOLWA
END:VEVENT
END:VCALENDAR