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BEGIN:VEVENT
SUMMARY:Yoshinori Gongyo (The University of Tokyo)
DTSTART;VALUE=DATE-TIME:20200423T160000Z
DTEND;VALUE=DATE-TIME:20200423T170000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/1
DESCRIPTION:Title: On a generalized Batyrev's cone conjecture\nby Yoshinor
i Gongyo (The University of Tokyo) as part of ZAG (Zoom Algebraic Geometry
) seminar\n\nAbstract: TBA\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Christopher Hacon (The University of Utah)
DTSTART;VALUE=DATE-TIME:20200428T160000Z
DTEND;VALUE=DATE-TIME:20200428T170000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/2
DESCRIPTION:Title: Recent progress in the MMP for 3-folds and 4-folds in c
har p>0\nby Christopher Hacon (The University of Utah) as part of ZAG (Zoo
m Algebraic Geometry) seminar\n\nAbstract: TBA\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Arnaud Beauville (Université de Nice)
DTSTART;VALUE=DATE-TIME:20200430T150000Z
DTEND;VALUE=DATE-TIME:20200430T160000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/3
DESCRIPTION:Title: Vector bundles on Fano threefolds and K3 surfaces\nby A
rnaud Beauville (Université de Nice) as part of ZAG (Zoom Algebraic Geome
try) seminar\n\nAbstract: TBA\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chen Jiang (Shanghai Center for Mathematical Sciences\, Fudan Univ
ersity)
DTSTART;VALUE=DATE-TIME:20200505T150000Z
DTEND;VALUE=DATE-TIME:20200505T160000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/4
DESCRIPTION:Title: Minimal log discrepancies of 3-dimensional non-canonica
l singularities\nby Chen Jiang (Shanghai Center for Mathematical Sciences\
, Fudan University) as part of ZAG (Zoom Algebraic Geometry) seminar\n\n\n
Abstract\nCanonical and terminal singularities\, introduced by Reid\, appe
ar naturally in minimal model program and play important roles in the bira
tional classification of higher dimensional algebraic varieties. Such sing
ularities are well-understood in dimension 3\, while the property of non-c
anonical singularities is still mysterious. We investigate the difference
between canonical and non-canonical singularities via minimal log discrepa
ncies (MLD). We show that there is a gap between MLD of 3-dimensional non-
canonical singularities and that of 3-dimensional canonical singularities\
, which is predicted by a conjecture of Shokurov. This result on local sin
gularities has applications to global geometry of Calabi–Yau 3-folds. We
show that the set of all non-canonical klt Calabi–Yau 3-folds are bound
ed modulo flops\, and the global indices of all klt Calabi–Yau 3-folds a
re bounded from above.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Samuel Grushevsky (Stony Brook University)
DTSTART;VALUE=DATE-TIME:20200507T180000Z
DTEND;VALUE=DATE-TIME:20200507T190000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/5
DESCRIPTION:Title: Geometry of moduli of cubic threefolds\nby Samuel Grush
evsky (Stony Brook University) as part of ZAG (Zoom Algebraic Geometry) se
minar\n\n\nAbstract\nThe moduli space of cubic threefolds can be thought o
f as a GIT quotient of the projective space of all cubic polynomials\, stu
died via the period map to a ball quotient\, or via the intermediate Jacob
ians. We describe the relations between various compactifications of the m
oduli space of cubic threefolds that arise in these ways\, and compute the
ir cohomology. Based on joint works with S. Casalaina-Martin\, K. Hulek\,
R. Laza.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kristin De Vleming (University of California\, San Diego)
DTSTART;VALUE=DATE-TIME:20200512T160000Z
DTEND;VALUE=DATE-TIME:20200512T170000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/6
DESCRIPTION:Title: Wall crossing for K-moduli spaces of plane curves\nby K
ristin De Vleming (University of California\, San Diego) as part of ZAG (Z
oom Algebraic Geometry) seminar\n\n\nAbstract\nThis talk will focus on com
pactifications of the moduli space of smooth plane curves of degree d at l
east 4. We will regard a plane curve as a log Fano pair (P2\, aC)\, where
a is a rational number\, and study the compactifications arising from K s
tability for these pairs and log Fano pairs in general. We establish a wa
ll crossing framework to study these spaces as a varies and show that\, wh
en a is small\, the moduli space coming from K stability is isomorphic to
the GIT moduli space. We describe all wall crossings for degree 4\, 5\, a
nd 6 plane curves and discuss the picture for general Q-Gorenstein smootha
ble log Fano pairs. This is joint work with Kenneth Ascher and Yuchen Liu
.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:John Christian Ottem (University of Oslo)
DTSTART;VALUE=DATE-TIME:20200514T153000Z
DTEND;VALUE=DATE-TIME:20200514T163000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/7
DESCRIPTION:Title: Tropical degenerations and stable rationality\nby John
Christian Ottem (University of Oslo) as part of ZAG (Zoom Algebraic Geomet
ry) seminar\n\nAbstract: TBA\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mircea Mustață (University of Michigan)
DTSTART;VALUE=DATE-TIME:20200519T170000Z
DTEND;VALUE=DATE-TIME:20200519T180000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/11
DESCRIPTION:Title: Minimal exponent and Hodge filtrations\nby Mircea Musta
ță (University of Michigan) as part of ZAG (Zoom Algebraic Geometry) sem
inar\n\n\nAbstract\nI will discuss an invariant of singularities\, Saito's
minimal exponent\, and its connections with various other invariants of s
ingularities. The minimal exponent is a refinement of the log canonical th
reshold that can be used to also measure rational hypersurface singulariti
es. This is based on joint work with Mihnea Popa.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Zsolt Patakfalvi (École polytechnique fédérale de Lausanne)
DTSTART;VALUE=DATE-TIME:20200526T170000Z
DTEND;VALUE=DATE-TIME:20200526T180000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/12
DESCRIPTION:Title: On the Beauville-Bogomolov decomposition in positive ch
aracteristic\nby Zsolt Patakfalvi (École polytechnique fédérale de Laus
anne) as part of ZAG (Zoom Algebraic Geometry) seminar\n\n\nAbstract\nAbst
ract: I will present a joint with Maciej Zdanowicz towards a positive cha
racteristic version of the Beauville-Bogomolov decomposition. Over the com
plex numbers this decomposition was shown using differential geometry meth
ods in the 70's and in the 80's. It concerns varieties with trivial canoni
cal bundle\, which we call K-trivial here. The main statement over the com
plex number is that smooth projective K-trivial varieties admit an etale c
over which splits as a product of three types of varieties: abelian\, Cala
bi-Yau and symplectic. I will present a similar statement in positive char
acteristic for (weakly) ordinary K-trivial varieties\, the proof of which
uses purely positive characteristic methods.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Xavier Roulleau (University of Aix-Marseille)
DTSTART;VALUE=DATE-TIME:20200521T110000Z
DTEND;VALUE=DATE-TIME:20200521T120000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/13
DESCRIPTION:Title: On the geometric models of K3 surfaces with finite auto
morphism group and Picard number larger than two\nby Xavier Roulleau (Univ
ersity of Aix-Marseille) as part of ZAG (Zoom Algebraic Geometry) seminar\
n\n\nAbstract\nVinberg and Nikulin classified K3 surfaces which have finit
e automorphism group and Picard number 4 and 3\,5\,..\,19 respectively. Th
at classification is lattice theoretic\, according to the Neron-Severi gro
up of these surfaces\; there are 118 such lattices. In this talk I will di
scuss on the geometric construction of these surfaces (by double coverings
or complete intersections) and describe their (finite) set of (-2)-curves
\, which gives the ample cone. Most of the moduli spaces of these K3 surfa
ces are unirational. A part of this talk is based on a joint work with Mic
hela Artebani and Claudia Correa Diesler.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexandra Kuznetsova (Higher School of Economics)
DTSTART;VALUE=DATE-TIME:20200528T140000Z
DTEND;VALUE=DATE-TIME:20200528T150000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/18
DESCRIPTION:Title: Sextic double solids\nby Alexandra Kuznetsova (Higher S
chool of Economics) as part of ZAG (Zoom Algebraic Geometry) seminar\n\n\n
Abstract\nAbstract: One of the first examples of unirational non-rational
threefold was provided by Artin and Mumford and it was a double cover of P
^3 branched in a nodal quartic surface\, so called quartic double solid.\n
Then Endrass studied this class of varieties and showed that the example b
y Artin and Mumford gives a unique family of non-rational nodal quartic do
uble solids. I am going to tell about the next interesting class of threef
olds --- nodal sextic double solids. I will describe 4 families of them su
ch that any non-rational variety of this type lies in one of those familie
s and explain the proof.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Stefan Schreieder (Leibniz University)
DTSTART;VALUE=DATE-TIME:20200602T110000Z
DTEND;VALUE=DATE-TIME:20200602T120000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/19
DESCRIPTION:Title: Equality in the Bogomolov-Miyaoka-Yau inequality in the
non-general type case\nby Stefan Schreieder (Leibniz University) as part
of ZAG (Zoom Algebraic Geometry) seminar\n\n\nAbstract\nWe classify all go
od minimal models of dimension n and with vanishing Chern number $c_1^{n-2
}c_2(X)=0$\, which corresponds to equality in the Bogomolov-Miyaoka—Yau
inequality in the non-general type case. Here the most interesting case is
that of Kodaira dimension n-1\, where any minimal model is known to be go
od. Our result solves completely a problem a Kollar. In dimension three\,
our approach together with previous work of Grassi and Kollar also leads t
o a complete solution of a conjecture of Kollar\, asserting that on a mini
mal threefold\, c_1c_2 is either zero or universally bounded away from zer
o. Joint work with Feng Hao.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Caucher Birkar (University of Cambridge)
DTSTART;VALUE=DATE-TIME:20200604T130000Z
DTEND;VALUE=DATE-TIME:20200604T140000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/20
DESCRIPTION:Title: Geometry of polarised varieties\nby Caucher Birkar (Uni
versity of Cambridge) as part of ZAG (Zoom Algebraic Geometry) seminar\n\n
\nAbstract\nI will talk about projective varieties polarised by ample divi
sors (or more generally nef and big divisors) in particular from a biratio
nal geometry point of view\, and present some recent results in this direc
tion.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yuri Prokhorov (Moscow State University)
DTSTART;VALUE=DATE-TIME:20200609T153000Z
DTEND;VALUE=DATE-TIME:20200609T163000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/21
DESCRIPTION:Title: General elephants for 3-fold extremal contractions\nby
Yuri Prokhorov (Moscow State University) as part of ZAG (Zoom Algebraic Ge
ometry) seminar\n\n\nAbstract\nI will discuss effective results on the cla
ssification of extremal contractions in the 3-dimensional MMP. In particul
ar\, I will present some recent result based on joint work with Shigefumi
Mori on the existence of general elephants.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ilya Zharkov (Kansas State University)
DTSTART;VALUE=DATE-TIME:20200611T140000Z
DTEND;VALUE=DATE-TIME:20200611T150000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/22
DESCRIPTION:Title: Topological SYZ fibrations with discriminant in codimen
sion 2\nby Ilya Zharkov (Kansas State University) as part of ZAG (Zoom Alg
ebraic Geometry) seminar\n\n\nAbstract\nTo date only for K3 surfaces (triv
ial) and the quintic threefold (due to M. Gross) the discriminant can be m
ade to be in codimension two. I will outline the source of the problem and
how to resolve it in much more general situations using phase and over-tr
opical pairs-of-pants. Joint project with Helge Ruddat.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nikolaos Tziolas (University of Cyprus)
DTSTART;VALUE=DATE-TIME:20200616T153000Z
DTEND;VALUE=DATE-TIME:20200616T163000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/23
DESCRIPTION:Title: Vector fields on canonically polarized surfaces\nby Nik
olaos Tziolas (University of Cyprus) as part of ZAG (Zoom Algebraic Geomet
ry) seminar\n\n\nAbstract\nIn this talk I will present some results about
the geometry of canonically polarized surfaces defined over a field of po
sitive characteristic which have a nontrivial global vector field\, equiva
lently non reduced automorphism scheme\, and the implications that the exi
stence of such surfaces has in the moduli problem of canonically polarized
surfaces.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Claire Voisin (Collège de France)
DTSTART;VALUE=DATE-TIME:20200618T140000Z
DTEND;VALUE=DATE-TIME:20200618T150000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/24
DESCRIPTION:Title: Triangle varieties and surface decomposition of hyper-K
ahler manifolds\nby Claire Voisin (Collège de France) as part of ZAG (Zoo
m Algebraic Geometry) seminar\n\n\nAbstract\nIn recent years\, new constru
ctions of complete families of polarized hyper-Kahler manifolds have been
found starting from Fano geometry. These hyper-Kahler manifolds also appea
r as general deformations of Hilbert schemes of K3 surfaces or O'Grady man
ifolds. I will introduce the notion of surface decomposition for a variety
X with a nontrivial Hodge structure on degree 2 cohomology. I will show t
hat this notion is restrictive topologically\, as it implies Beauville-Fuj
iki type relations. I will also show the existence of such a surface deco
mposition for the general hyper-Kahler manifolds mentioned above. This
has interesting consequences on Beauville's conjecture on the Chow ring of
hyper-Kahler manifolds.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alexander Polishchuk (University of Oregon)
DTSTART;VALUE=DATE-TIME:20200623T170000Z
DTEND;VALUE=DATE-TIME:20200623T180000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/25
DESCRIPTION:Title: Hyperelliptic limits of quadrics through canonical curv
es and the super-Schottky locus\nby Alexander Polishchuk (University of Or
egon) as part of ZAG (Zoom Algebraic Geometry) seminar\n\n\nAbstract\nI wi
ll describe joint works with Eric Rains and with Giovanni Felder and David
Kazhdan. The first part will be about a classical topic of quadrics throu
gh canonically embedded curves. We study limiting quadrics as canonical cu
rves approach a hyperelliptic limit. There is a surprizingly simple descri
ption of all such limits. I will also discuss the connection to ribbon cur
ves (which are thickenings of rational normal curves) and to the blow up o
f the moduli space of curves at the hyperelliptic locus. In the second par
t I will talk about the super-period map for supercurves and the calculati
on of its infinitesimal variation. This variation is given by a natural Ma
ssey product that can be defined for any curve with a theta-characteristic
. Combining this with the result of part 1 we get some information about t
he super-Schottky locus.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Mumford (Harvard University and Brown University)
DTSTART;VALUE=DATE-TIME:20200625T150000Z
DTEND;VALUE=DATE-TIME:20200625T160000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/26
DESCRIPTION:Title: A moduli space in the differential geometry world\nby D
avid Mumford (Harvard University and Brown University) as part of ZAG (Zoo
m Algebraic Geometry) seminar\n\n\nAbstract\nThe space of simple closed sm
ooth plane curves is an infinite dimensional manifold and supports a great
diversity of Riemannian metrics. They have very diverse curvature propert
ies and even include universal Teichmuller space. I want to talk in partic
ular about a recent example: modeling 2D waves in water (aka gravity waves
) that some believe explains so-called rogue waves.\nAfter the talk\, we p
lan to have Q&A session at 16:00 GMT. If you have a question for Prof. Mum
ford\, let Ivan Cheltsov know in advance (by e-mail).\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Izzet Coskun (University of Illinois at Chicago)
DTSTART;VALUE=DATE-TIME:20200630T150000Z
DTEND;VALUE=DATE-TIME:20200630T160000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/27
DESCRIPTION:Title: The stabilization of the cohomology of moduli spaces of
sheaves on surfaces\nby Izzet Coskun (University of Illinois at Chicago)
as part of ZAG (Zoom Algebraic Geometry) seminar\n\n\nAbstract\nThe Betti
numbers of the Hilbert scheme of points on a smooth\, irreducible projecti
ve surface have been computed by Gottsche. These numbers stabilize as the
number of points tends to infinity. In contrast\, the Betti numbers of mod
uli spaces of semistable sheaves on a surface are not known in general. In
joint work with Matthew Woolf\, we conjecture these also stabilize and th
at the stable numbers do not depend on the rank. We verify the conjecture
for large classes of surfaces. I will discuss our conjecture and provide t
he evidence for it.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Susanna Zimmermann (Université Angers)
DTSTART;VALUE=DATE-TIME:20200702T100000Z
DTEND;VALUE=DATE-TIME:20200702T110000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/28
DESCRIPTION:Title: Finite quotients of Cremona groups\nby Susanna Zimmerma
nn (Université Angers) as part of ZAG (Zoom Algebraic Geometry) seminar\n
\n\nAbstract\nThe Cremona group is the group of birational self-maps of th
e projective space\, and it is very very big. While in dimension 2 over al
gebraically closed fields there are no finite quotients of this group\, th
ere are many such quotients over non-closed fields and in higher dimension
. I will discuss why this is and how these quotients come up.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ziquan Zhuang (MIT)
DTSTART;VALUE=DATE-TIME:20200707T170000Z
DTEND;VALUE=DATE-TIME:20200707T180000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/29
DESCRIPTION:Title: K-stability of Fano varieties via admissible flags\nby
Ziquan Zhuang (MIT) as part of ZAG (Zoom Algebraic Geometry) seminar\n\n\n
Abstract\nI'll present a general approach to prove the K-stability of expl
icit Fano varieties. Among the applications\, we confirm the existence of
K\\"ahler-Einstein metrics on all smooth Fano hypersurfaces of Fano index
two\, calculate the stability thresholds of some Fano varieties and provid
e a counterexample to the Higher Rank Finite Generation conjecture. Based
on joint work with Hamid Ahmadinezhad.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Harold Blum (University of Utah)
DTSTART;VALUE=DATE-TIME:20200709T150000Z
DTEND;VALUE=DATE-TIME:20200709T160000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/30
DESCRIPTION:Title: On properness of K-moduli spaces and destabilizations o
f Fano varieties\nby Harold Blum (University of Utah) as part of ZAG (Zoom
Algebraic Geometry) seminar\n\n\nAbstract\nK-stability is an algebraic no
tion that detects when a smooth Fano variety admits a Kahler-Einstein metr
ic. Recently\, there has been significant progress on constructing moduli
spaces of K-polystable Fano varieties using algebraic methods. One of the
remaining open problems is to show that these moduli spaces are proper. In
this talk\, I will discuss work with Daniel Halpern-Leistner\, Yuchen Liu
\, and Chenyang Xu\, in which we reduce the properness of such K-moduli sp
aces to the existence of certain optimal destabilization of Fano varietie
s.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hélène Esnault (Freie Universität Berlin)
DTSTART;VALUE=DATE-TIME:20200714T140000Z
DTEND;VALUE=DATE-TIME:20200714T150000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/31
DESCRIPTION:Title: Density of arithmetic representations\nby Hélène Esna
ult (Freie Universität Berlin) as part of ZAG (Zoom Algebraic Geometry) s
eminar\n\n\nAbstract\nThe lecture surveys recent work with Moritz Kerz. T
he motivation is the conjecture that the Hard-Lefschetz (HL) property hol
ds on smooth projective varieties defined over algebraically closed char.
$p>0$ fields for cohomology with values in semi-simple $\\ell$-adic loca
l systems $V$. We know it is true if $V$ comes from geometry (Deligne\, Be
ilinson-Bernstein-Deligne-Gabber) by Deligne’s theory of weights. In abs
ence of weights\, we proved it if $V$ has rank $1$ and reduced the whole H
L conjecture to a density conjecture on arithmetic semi-simple $\\ell$-adi
c systems on $P^1$ minus $3$ closed points\, which we can prove in rank $2
$.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matthias Schuett (Leibniz Universität Hannover)
DTSTART;VALUE=DATE-TIME:20200716T153000Z
DTEND;VALUE=DATE-TIME:20200716T163000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/32
DESCRIPTION:Title: Rational curves on Enriques surfaces\, but only few\nby
Matthias Schuett (Leibniz Universität Hannover) as part of ZAG (Zoom Alg
ebraic Geometry) seminar\n\n\nAbstract\nRational curves play a fundamental
role for the structure of an Enriques surface. I will first review the ge
neral theory before focussing on the case of low degree rational curves. T
o this end\, I will discuss joint work with S. Rams (Krakow) which develop
s an explicit sharp bound on the number of rational curves of given degree
relative to the degree of the surface. The proof builds on a general argu
ment in parallel to the case of K3 surfaces which allows us to extend boun
ds of Miyaoka and Degtyarev.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jihun Park (POSTECH)
DTSTART;VALUE=DATE-TIME:20200721T110000Z
DTEND;VALUE=DATE-TIME:20200721T120000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/33
DESCRIPTION:Title: Cayley octads\, plane quartic curves\, Del Pezzo surfac
es of degree 2 and double Veronese cones\nby Jihun Park (POSTECH) as part
of ZAG (Zoom Algebraic Geometry) seminar\n\n\nAbstract\nA net of quadrics
in the 3-dimensional projective space whose singular members are parametri
zed by a smooth plane quartic curve has exactly eight distinct base points
\, called a regular Cayley octad. It is a classical result that there is
a one-to-one correspondence between isomorphism classes of regular Cayley
octads and isomorphism classes of smooth plane quartic curves equipped wi
th even theta-characteristics. We can also easily observe a one-to-one co
rrespondence between isomorphism classes of smooth plane quartic curves an
d isomorphism classes of smooth Del Pezzo surfaces of degree 2. In this ta
lk\, we set up a one-to-one correspondence between isomorphism classes of
smooth plane quartic curves and isomorphism classes of double Veronese con
es with 28-singular points. Also\, we explain how the 36 even theta charac
teristics of a given smooth quartic curve appear in the corresponding doub
le Veronese cone. This is a joint work with Hamid Ahmadinezhad\, Ivan Chel
tsov and Constantin Shramov.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ruadhai Dervan (University of Cambridge)
DTSTART;VALUE=DATE-TIME:20200723T150000Z
DTEND;VALUE=DATE-TIME:20200723T160000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/34
DESCRIPTION:Title: Stability of fibrations\nby Ruadhai Dervan (University
of Cambridge) as part of ZAG (Zoom Algebraic Geometry) seminar\n\n\nAbstra
ct\nThe notion of K-stability of a polarised variety has been heavily stud
ied in recent years\, due to its link both with moduli theory (one should
be able to form moduli spaces of K-stable varieties) and to Kahler geometr
y (K-stability should be equivalent to the existence of a constant scalar
curvature Kahler metric on the variety). This story has been particularly
successful for Fano varieties. I will describe a notion of stability for p
olarised fibrations\, which generalises K-stability of polarised varieties
when the base of the fibration is a point\, and slope stability of a vect
or bundle when the variety is the projectivisation of a vector bundle. I w
ill speculate that one should be able to form moduli spaces of stable fibr
ations\, much as one can form moduli spaces of slope stable vector bundles
over a fixed base. The main result\, however\, will be a description of t
he link with certain canonical metrics on fibrations. This is joint work w
ith Lars Sektnan.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jean-Pierre Demailly (Université Grenoble Alpes)
DTSTART;VALUE=DATE-TIME:20200728T153000Z
DTEND;VALUE=DATE-TIME:20200728T163000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/35
DESCRIPTION:Title: Hermitian-Yang-Mills approach to the conjecture of Grif
fiths on the positivity of ample vector bundles\nby Jean-Pierre Demailly (
Université Grenoble Alpes) as part of ZAG (Zoom Algebraic Geometry) semin
ar\n\n\nAbstract\nGiven a vector bundle of arbitrary rank with ample deter
minant line bundle on a projective manifold\, we propose a new elliptic sy
stem of differential equations of Hermitian-Yang-Mills type for the curvat
ure tensor. The system is designed so that solutions provide Hermitian met
rics with positive curvature in the sense of Griffiths - and even in the s
tronger dual Nakano sense. As a consequence\, if an existence result could
be obtained for every ample vector bundle\, the Griffiths conjecture on
the equivalence between ampleness and positivity of vector bundles would b
e settled. We also discuss a new concept of volume for vector bundles.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ziwen Zhu (University of Utah)
DTSTART;VALUE=DATE-TIME:20200730T150000Z
DTEND;VALUE=DATE-TIME:20200730T163000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/36
DESCRIPTION:Title: Equivariant K-stability under finite group action\nby Z
iwen Zhu (University of Utah) as part of ZAG (Zoom Algebraic Geometry) sem
inar\n\n\nAbstract\nEquivariant K-stability is defined via equivariant tes
t configurations. By definition it is weaker than the usual K-stability an
d for varieties with large symmetry\, it is often easier to check equivari
ant K-stability. For reductive group action\, it is conjectured that equiv
ariant K-polystability implies K-polystability. In this talk\, I will disc
uss recent results about equivariant K-stability and present a proof of th
e conjecture for finite group action. The talk is based on joint work with
Yuchen Liu.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hamid Ahmadinezhad (Loughborough University)
DTSTART;VALUE=DATE-TIME:20200804T140000Z
DTEND;VALUE=DATE-TIME:20200804T150000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/37
DESCRIPTION:Title: Birational geometry of Fano 3-fold hypersurfaces of hig
her index\nby Hamid Ahmadinezhad (Loughborough University) as part of ZAG
(Zoom Algebraic Geometry) seminar\n\n\nAbstract\nI will speak about an app
roach to birational classification of Fano 3-folds\, post MMP. As a part o
f this general guideline\, I will highlight some recent results about bira
tional geometry of Fano hypersurfaces of higher index. The latter is a joi
nt work with Ivan Cheltsov and Jihun Park.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Marina Logares (Universidad Complutense de Madrid)
DTSTART;VALUE=DATE-TIME:20200806T150000Z
DTEND;VALUE=DATE-TIME:20200806T160000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/38
DESCRIPTION:Title: Poisson and symplectic geometry of the moduli spaces of
Higgs bundles\nby Marina Logares (Universidad Complutense de Madrid) as p
art of ZAG (Zoom Algebraic Geometry) seminar\n\n\nAbstract\nI will talk ab
out some natural Poisson and symplectic properties of the moduli spaces of
Higgs bundles when some extra structure\, such as a framing\, is added. T
his is an overview of various past and ongoing work with I. Biswas\, J. Ma
rtens\, A. Peón-Nieto and S. Szabó. I will not assume any previous knowl
edge on the subject.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Robert Lazarsfeld (Stony Brook University)
DTSTART;VALUE=DATE-TIME:20200811T170000Z
DTEND;VALUE=DATE-TIME:20200811T180000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/39
DESCRIPTION:Title: Cayley-Bacharach theorems and multiplier ideals\nby Rob
ert Lazarsfeld (Stony Brook University) as part of ZAG (Zoom Algebraic Geo
metry) seminar\n\n\nAbstract\nCayley-Bacharach theorems originate in the c
lassical statement if two plane curves of degrees c and d meet in cd poi
nts\, then any curve of degree (c + d - 3) passing through all but one of
these points must also pass through the remaining one. Following work of G
riffiths and Harris in the 1970s\, one now sees this as a special case of
a general result about zero-loci of sections of a vector bundle. I will ex
plain how bringing multiplier ideals into the picture leads (for free) to
a variant that allows for excess vanishing. This is joint work with Lawren
ce Ein.\n
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yuchen Liu (Yale University)
DTSTART;VALUE=DATE-TIME:20200813T150000Z
DTEND;VALUE=DATE-TIME:20200813T160000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/40
DESCRIPTION:Title: On K-stability of cubic hypersurfaces\nby Yuchen Liu (Y
ale University) as part of ZAG (Zoom Algebraic Geometry) seminar\n\nIntera
ctive livestream: https://us02web.zoom.us/j/9918493831\n\nAbstract\nK-stab
ility of Fano varieties is an algebro-geometric stability condition charac
terizing the existence of K\\"ahler-Einstein metrics. Recent progress on K
-stability suggests that it provides a good moduli theory for Fano varieti
es. In this talk\, I will explain how K-moduli spaces can help us prove K-
stability of smooth cubic hypersurfaces in dimension at most 4\, using a l
ocal-to-global volume comparison result. Part of this talk is based on joi
nt work with Chenyang Xu.\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alessio Corti (Imperial College London)
DTSTART;VALUE=DATE-TIME:20200818T170000Z
DTEND;VALUE=DATE-TIME:20200818T180000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/41
DESCRIPTION:Title: Smoothing Gorenstein toric affine 3-folds\nby Alessio
Corti (Imperial College London) as part of ZAG (Zoom Algebraic Geometry) s
eminar\n\nInteractive livestream: https://us02web.zoom.us/j/9918493831\n\n
Abstract\nI will state a conjecture on the smoothing components of the def
ormation space\, and discuss one or more of the following topics: possible
strategies for proving it\, applications to the Fanosearch program\, glob
al and higher dimensional analogs. The talk is based on a recent collabora
tion with Andrea Petracci and Matej Filip.\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:Nicola Pagani (University of Liverpool)
DTSTART;VALUE=DATE-TIME:20200820T150000Z
DTEND;VALUE=DATE-TIME:20200820T160000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/42
DESCRIPTION:Title: Classifying fine compactified universal Jacobians\nby N
icola Pagani (University of Liverpool) as part of ZAG (Zoom Algebraic Geom
etry) seminar\n\nInteractive livestream: https://us02web.zoom.us/j/9918493
831\n\nAbstract\nWe introduce the notion of a fine compactified Jacobian o
f a nodal curve\, as an arbitrary compact open subspace of the moduli spac
e of rank-1 torsion-free simple sheaves. We show that fine compactified Ja
cobians correspond to a certain combinatorial datum\, which is obtained by
only keeping track\, for all sheaves\, of (1) the locus where it fails to
be locally free\, and (2) its multidegree. This notion generalizes to fla
t families of curves\, and so does its combinatorial counterpart. When the
family is the universal family over the moduli space of curves\, we have
the following results: (a) in the absence of marked points\, we can fully
classify these combinatorial data and deduce that the only fine compactifi
ed universal Jacobians are the classical ones (which were constructed by P
andharipande and Simpson in the nineties) and (b) in the presence of marke
d points there are exotic (and new) examples that cannot be obtained as co
mpactified universal Jacobians associated to a polarization. This is a joi
nt work in progress with Jesse Kass.\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:Christian Boehning (University of Warwick)
DTSTART;VALUE=DATE-TIME:20200825T170000Z
DTEND;VALUE=DATE-TIME:20200825T180000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/43
DESCRIPTION:Title: Rigid\, not infinitesimally rigid surfaces of general t
ype with ample canonical bundle\nby Christian Boehning (University of Warw
ick) as part of ZAG (Zoom Algebraic Geometry) seminar\n\nInteractive lives
tream: https://us02web.zoom.us/j/9918493831\n\nAbstract\nIn the talk I wil
l report on work in progress\, joint with Roberto Pignatelli and Hans-Chri
stian von Bothmer\, that concerns the construction of surfaces of general
type with ample canonical bundle and Kuranishi space (and possibly also Gi
eseker moduli space) a non-reduced point. The main tools are configuration
s of lines and their incidence schemes as well as the theory of abelian co
vers due to Pardini and others.\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:Robert Berman (Chalmers University of Technology)
DTSTART;VALUE=DATE-TIME:20200827T100000Z
DTEND;VALUE=DATE-TIME:20200827T110000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/44
DESCRIPTION:Title: Kahler-Einstein metrics\, Archimedean Zeta functions an
d phase transitions\nby Robert Berman (Chalmers University of Technology)
as part of ZAG (Zoom Algebraic Geometry) seminar\n\nInteractive livestream
: https://us02web.zoom.us/j/9918493831\n\nAbstract\nWhile the existence of
a unique Kahler-Einstein metrics on a canonically polarized manifold X wa
s established already in the seventies there are very few explicit formula
s available (even in the case of complex curves!). In this talk I will giv
e a non-technical introduction to a probabilistic approach to Kahler-Einst
ein metrics\, which\, in particular\, yields canonical approximations of t
he Kahler-Einstein metric on X. The approximating metrics in question are
expressed as explicit period integrals and the conjectural extension to th
e case of a Fano variety leads to some intriguing connections with Zeta fu
nctions and the theory of phase transitions in statistical mechanics.\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jarod Alper (University of Washington)
DTSTART;VALUE=DATE-TIME:20200903T170000Z
DTEND;VALUE=DATE-TIME:20200903T180000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/46
DESCRIPTION:by Jarod Alper (University of Washington) as part of ZAG (Zoom
Algebraic Geometry) seminar\n\nInteractive livestream: https://us02web.zo
om.us/j/9918493831\nAbstract: TBA\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andreas Höring (Université Côte d'Azur)
DTSTART;VALUE=DATE-TIME:20200908T100000Z
DTEND;VALUE=DATE-TIME:20200908T110000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/47
DESCRIPTION:by Andreas Höring (Université Côte d'Azur) as part of ZAG (
Zoom Algebraic Geometry) seminar\n\nInteractive livestream: https://us02we
b.zoom.us/j/9918493831\nAbstract: TBA\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:Joaquín Moraga (Princeton University)
DTSTART;VALUE=DATE-TIME:20200910T160000Z
DTEND;VALUE=DATE-TIME:20200910T170000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/48
DESCRIPTION:by Joaquín Moraga (Princeton University) as part of ZAG (Zoom
Algebraic Geometry) seminar\n\nInteractive livestream: https://us02web.zo
om.us/j/9918493831\nAbstract: TBA\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:Julie Rana (Lawrence University)
DTSTART;VALUE=DATE-TIME:20200915T150000Z
DTEND;VALUE=DATE-TIME:20200915T160000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/49
DESCRIPTION:by Julie Rana (Lawrence University) as part of ZAG (Zoom Algeb
raic Geometry) seminar\n\nInteractive livestream: https://us02web.zoom.us/
j/9918493831\nAbstract: TBA\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anthony Varilly-Alvarado (Rice University)
DTSTART;VALUE=DATE-TIME:20200917T150000Z
DTEND;VALUE=DATE-TIME:20200917T160000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/50
DESCRIPTION:by Anthony Varilly-Alvarado (Rice University) as part of ZAG (
Zoom Algebraic Geometry) seminar\n\nInteractive livestream: https://us02we
b.zoom.us/j/9918493831\nAbstract: TBA\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jean-Louis Colliot-Thelene (Université Paris-Sud)
DTSTART;VALUE=DATE-TIME:20200922T140000Z
DTEND;VALUE=DATE-TIME:20200922T150000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/51
DESCRIPTION:by Jean-Louis Colliot-Thelene (Université Paris-Sud) as part
of ZAG (Zoom Algebraic Geometry) seminar\n\nInteractive livestream: https:
//us02web.zoom.us/j/9918493831\nAbstract: TBA\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:Alan Thompson (Loughborough University)
DTSTART;VALUE=DATE-TIME:20200924T100000Z
DTEND;VALUE=DATE-TIME:20200924T110000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/52
DESCRIPTION:by Alan Thompson (Loughborough University) as part of ZAG (Zoo
m Algebraic Geometry) seminar\n\nInteractive livestream: https://us02web.z
oom.us/j/9918493831\nAbstract: TBA\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yuri Zarhin (Penn State University)
DTSTART;VALUE=DATE-TIME:20200929T140000Z
DTEND;VALUE=DATE-TIME:20200929T150000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/53
DESCRIPTION:by Yuri Zarhin (Penn State University) as part of ZAG (Zoom Al
gebraic Geometry) seminar\n\nInteractive livestream: https://us02web.zoom.
us/j/9918493831\nAbstract: TBA\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:Burt Totaro (UCLA)
DTSTART;VALUE=DATE-TIME:20201001T160000Z
DTEND;VALUE=DATE-TIME:20201001T170000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/54
DESCRIPTION:by Burt Totaro (UCLA) as part of ZAG (Zoom Algebraic Geometry)
seminar\n\nInteractive livestream: https://us02web.zoom.us/j/9918493831\n
Abstract: TBA\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:Junliang Shen (MIT)
DTSTART;VALUE=DATE-TIME:20201006T160000Z
DTEND;VALUE=DATE-TIME:20201006T170000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/55
DESCRIPTION:by Junliang Shen (MIT) as part of ZAG (Zoom Algebraic Geometry
) seminar\n\nInteractive livestream: https://us02web.zoom.us/j/9918493831\
nAbstract: TBA\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:Timothy Logvinenko (Cardiff University)
DTSTART;VALUE=DATE-TIME:20201008T153000Z
DTEND;VALUE=DATE-TIME:20201008T163000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/56
DESCRIPTION:by Timothy Logvinenko (Cardiff University) as part of ZAG (Zoo
m Algebraic Geometry) seminar\n\nInteractive livestream: https://us02web.z
oom.us/j/9918493831\n\nAbstract\nAbstract: Ordinary braid group Br_n is a
well-known algebraic structure which encodes configurations of n non-touch
ing strands (“braids”) up to continious transformations (“isotopies
”). A classical result of Khovanov and Thomas states that there is a nat
ural categorical action of Br_n on the derived category of the cotangent b
undle of the variety of complete flags in C^n.\nIn this talk\, I will intr
oduce a new structure: the category GBr_n of generalised braids. These are
the braids whose strands are allowed to touch in a certain way. They have
multiple endpoint configurations and can be non-invertible\, thus forming
a category rather than a group. In the context of triangulated categories
\, it is natural to impose certain relations which result in the notion of
a skein-triangulated representation of GBr_n.\nA decade-old conjecture st
ates that there a skein-triangulated action of GBr_n on the cotangent bund
les of the varieties of full and partial flags in C^n. We prove this conje
cture for n = 3. We also show that any categorical action of Br_n can be l
ifted to a skein-triangulated action of GBr_n\, which behaves like a categ
orical nil Hecke algebra. This is a joint work with Rina Anno and Lorenzo
De Biase.\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ana-Maria Castravet (Université de Versailles St-Quentin-en-Yveli
nes)
DTSTART;VALUE=DATE-TIME:20201013T140000Z
DTEND;VALUE=DATE-TIME:20201013T150000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/57
DESCRIPTION:by Ana-Maria Castravet (Université de Versailles St-Quentin-e
n-Yvelines) as part of ZAG (Zoom Algebraic Geometry) seminar\n\nInteractiv
e livestream: https://us02web.zoom.us/j/9918493831\nAbstract: TBA\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sandra Di Rocco (KTH)
DTSTART;VALUE=DATE-TIME:20201015T140000Z
DTEND;VALUE=DATE-TIME:20201015T150000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/58
DESCRIPTION:by Sandra Di Rocco (KTH) as part of ZAG (Zoom Algebraic Geomet
ry) seminar\n\nInteractive livestream: https://us02web.zoom.us/j/991849383
1\nAbstract: TBA\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gergely Berczi (Aarhus University)
DTSTART;VALUE=DATE-TIME:20201020T150000Z
DTEND;VALUE=DATE-TIME:20201020T160000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/59
DESCRIPTION:by Gergely Berczi (Aarhus University) as part of ZAG (Zoom Alg
ebraic Geometry) seminar\n\nInteractive livestream: https://us02web.zoom.u
s/j/9918493831\nAbstract: TBA\n
URL:https://us02web.zoom.us/j/9918493831
END:VEVENT
BEGIN:VEVENT
SUMMARY:David Mumford (Harvard University and Brown University)
DTSTART;VALUE=DATE-TIME:20200625T160000Z
DTEND;VALUE=DATE-TIME:20200625T170000Z
DTSTAMP;VALUE=DATE-TIME:20200812T065717Z
UID:ZAG/60
DESCRIPTION:Title: Q&A with legendary geometers: David Mumford\nby David M
umford (Harvard University and Brown University) as part of ZAG (Zoom Alge
braic Geometry) seminar\n\n\nAbstract\nQ&A with David Mumford (please\, no
algebraic geometry questions). If you want to ask a question you should e
-mail it in advance to i.cheltsov@ed.ac.uk\n
END:VEVENT
END:VCALENDAR