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BEGIN:VEVENT
SUMMARY:Gavril Farkas (Humboldt University of Berlin)
DTSTART;VALUE=DATE-TIME:20200417T180000Z
DTEND;VALUE=DATE-TIME:20200417T193000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/1
DESCRIPTION:Title: Green’s conjecture via Koszul modules\nby Gavril Farkas (Humboldt
University of Berlin) as part of Stanford algebraic geometry seminar\n\n\
nAbstract\nUsing ideas from geometric group theory we provide a novel\napp
roach to Green’s Conjecture on syzygies of canonical curves. Via a\nstro
ng vanishing result for Koszul modules we deduce that a general\ncanonical
curve of genus g satisfies Green’s Conjecture when the\ncharacteristic
is zero or at least $(g+2)/2$. Our results are new in\npositive characteri
stic (and answer positively a conjecture of Eisenbud\nand Schreyer)\, wher
eas in characteristic zero they provide a different\nproof for theorems fi
rst obtained in two landmark papers by Voisin.\nJoint work with Aprodu\, P
apadima\, Raicu and Weyman.\n
LOCATION:https://researchseminars.org/talk/agstanford/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kirsten Wickelgren (Duke)
DTSTART;VALUE=DATE-TIME:20200424T180000Z
DTEND;VALUE=DATE-TIME:20200424T193000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/2
DESCRIPTION:Title: There are $160\,839 \\langle 1 \\rangle + 160\,650 \\langle -1\\rangle$
3-planes in a 7-dimensional cubic hypersurface\nby Kirsten Wickelgren
(Duke) as part of Stanford algebraic geometry seminar\n\n\nAbstract\nIt i
s a result of Debarre--Manivel that the variety of $d$-planes on a generic
complete intersection has the expected dimension. When this dimension is
0\, the number of such $d$-planes is given by the Euler number of a vector
bundle on a Grassmannian. There are several Euler numbers from $A^1$-homo
topy theory which take a vector bundle to a bilinear form. We equate some
of these\, including those of Barge-Morel\, Kass-W.\, Déglise-Jin-Khan\,
and one suggested by M.J. Hopkins\, A. Raksit\, and J.-P. Serre using dual
ity of coherent sheaves. We establish integrality results for this Euler c
lass\, and use this to compute the Euler classes associated to arithmetic
counts of d-planes on complete intersections in projective space in terms
of topological Euler numbers over the real and complex numbers. The exampl
e in the title uses work of Finashin-Kharlamov. This is joint work with To
m Bachmann.\n
LOCATION:https://researchseminars.org/talk/agstanford/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Burt Totaro (UCLA)
DTSTART;VALUE=DATE-TIME:20200501T190000Z
DTEND;VALUE=DATE-TIME:20200501T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/3
DESCRIPTION:Title: The Hilbert scheme of infinite affine space\nby Burt Totaro (UCLA)
as part of Stanford algebraic geometry seminar\n\n\nAbstract\nI will discu
ss the Hilbert scheme of $d$ points in affine $n$-space\, with some exampl
es. This space has many irreducible components for $n$ at least 3 and is p
oorly understood. Nonetheless\, in the limit where $n$ goes to infinity\,
we show that the Hilbert scheme of $d$ points in infinite affine space ha
s a very simple homotopy type. In fact\, it has the $A^1$-homotopy type of
the infinite Grassmannian $BGL(d-1)$. Many questions remain. (Joint with
Marc Hoyois\, Joachim Jelisiejew\, Denis Nardin\, Maria Yakerson.)\n
LOCATION:https://researchseminars.org/talk/agstanford/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Borys Kadets (MIT)
DTSTART;VALUE=DATE-TIME:20200501T174500Z
DTEND;VALUE=DATE-TIME:20200501T184500Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/4
DESCRIPTION:Title: 38406501359372282063949 & all that: Monodromy of Fano problems\nby
Borys Kadets (MIT) as part of Stanford algebraic geometry seminar\n\n\nAbs
tract\nA Fano problem is an enumerative problem of counting linear subspac
es on complete intersections. Some familiar examples are finding the numbe
r of lines on a cubic surface\, and finding the number of lines on the int
ersection of $2$ quadrics in $\\mathbb{P}^4$. Suppose a general complete i
ntersection of type $[d]=(d_1\, ...\, d_s)$ in $\\mathbb{P}^n$ contains fi
nitely many $r$-planes. To this Fano problem\, described by the triple $([
d]\,n\,r)$\, one can associate a group $G_{[d]\,n\,r}$\, the monodromy gro
up of the Fano problem\; it describes the permutations of $r$-planes on a
complete intersection of type $[d]$\, as the complete intersection varies.
I will show that $G_{[d]\,n\,r}$ is either a symmetric or an alternating
group for almost all Fano problems with an explicit list of exceptions\, a
nd describe the monodromy groups of the exceptional problems. An interesti
ng feature of this computation is that it avoids any local calculations\,
which seems necessary to get the result in full generality. This is joint
work with Sachi Hashimoto.\n\nDiscussion during the talk will be at https:
//tinyurl.com/2020-05-01-a\n(and this will be deleted in 3 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Julie Desjardins (Toronto)
DTSTART;VALUE=DATE-TIME:20200508T174500Z
DTEND;VALUE=DATE-TIME:20200508T184500Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/5
DESCRIPTION:Title: Density of rational points on a family of del Pezzo surface of degree 1
\nby Julie Desjardins (Toronto) as part of Stanford algebraic geometry
seminar\n\n\nAbstract\nLet $k$ be a number field and $X$ an algebraic var
iety over $k$. We want to study the set of $k$-rational points $X(k)$. For
example\, is $X(k)$ empty? If not\, is it dense with respect to the Zaris
ki topology? Del Pezzo surfaces are classified by their degrees $d$ (an in
teger between 1 and 9). Manin and various authors proved that for all del
Pezzo surfaces of degree $>1$ is dense provided that the surface has a $k$
-rational point (that lies outside a specific subset of the surface for $d
=2$). For $d=1$\, the del Pezzo surface always has a rational point. Howev
er\, we don't know it the set of rational points is Zariski-dense. In this
talk\, I present a result that is joint with Rosa Winter in which we prov
e the density of rational points for a specific family of del Pezzo surfac
es of degree 1 over $k$.\n\nThe discussion for Julie Desjardins’s talk i
s taking place not in zoom-chat\, but at https://tinyurl.com/stagMay08a (a
nd will be deleted after 3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Bjorn Poonen (MIT)
DTSTART;VALUE=DATE-TIME:20200508T190000Z
DTEND;VALUE=DATE-TIME:20200508T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/6
DESCRIPTION:Title: Bertini irreducibility theorems via statistics\nby Bjorn Poonen (MI
T) as part of Stanford algebraic geometry seminar\n\n\nAbstract\nLet $X \\
subset \\mathbb{P}^n$ be a geometrically irreducible subvariety\nwith $\\d
im X \\ge 2$\, over any field.\nLet $\\check{\\mathbb{P}}^n$ be the moduli
space\nparametrizing hyperplanes $H \\subset \\mathbb{P}^n$.\nLet $L \\su
bset \\check{\\mathbb{P}}^n$ be the locus parametrizing $H$\nfor which $H
\\cap X$ is geometrically irreducible.\nThe classical Bertini irreducibili
ty theorem states that\n$L$ contains a dense open subset of $\\check{\\mat
hbb{P}}^n$\,\nso the bad locus $L' := \\mathbb{P}^n - L$ satisfies $\\dim
L' \\le n-1$.\nBenoist improved this to $\\dim L' \\le \\operatorname{codi
m} X + 1$.\n\nWe describe a new way to prove and generalize such theorems\
,\nby reducing to the case of a finite field\nand studying the mean and va
riance\nof the number of points of a random hyperplane section.\nThis is j
oint work with Kaloyan Slavov.\n\nThe discussion for Bjorn Poonen’s talk
is taking place not in the zoom-chat\, but at https://tinyurl.com/stagMay
08b (and will be deleted after 3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rohini Ramadas (Brown)
DTSTART;VALUE=DATE-TIME:20200515T174500Z
DTEND;VALUE=DATE-TIME:20200515T184500Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/7
DESCRIPTION:Title: The locus of post-critically finite maps in the moduli space of self-ma
ps of $\\mathbb{P}^n$\nby Rohini Ramadas (Brown) as part of Stanford a
lgebraic geometry seminar\n\n\nAbstract\nA degree $d>1$ self-map $f$ of $\
\mathbb{P}^n$ is called post critically finite (PCF) if its critical hyper
surface $C_f$ is pre-periodic for $f$\, that is\, if there exist integers
$r \\geq 0$ and $k>0$ such that $f^{r+k}(C_f)$ is contained in $f^{r}(C_f)
$. \n\nI will discuss the question: what does the locus of PCF maps look l
ike as a subset of the moduli space of degree $d$ maps on $\\mathbb{P}^n$?
I’ll give a survey of many known results and some conjectures in dimens
ion $1$. I’ll then present a result\, joint with Patrick Ingram and Jose
ph Silverman\, that suggests that in dimensions two or greater\, PCF maps
are comparatively scarce in the moduli space of all self-maps.\n\nThe disc
ussion for Rohini Ramadas’s talk is taking place not in zoom-chat\, but
at https://tinyurl.com/2020-05-15-rr (and will be deleted after 3-7 days)
.\n
LOCATION:https://researchseminars.org/talk/agstanford/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rob Silversmith (Northeastern)
DTSTART;VALUE=DATE-TIME:20200515T190000Z
DTEND;VALUE=DATE-TIME:20200515T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/8
DESCRIPTION:Title: Studying subschemes of affine/projective space via matroids\nby Rob
Silversmith (Northeastern) as part of Stanford algebraic geometry seminar
\n\n\nAbstract\nGiven a homogeneous ideal $I$ in a polynomial ring\, one m
ay apply the following combinatorial operation: for each degree $d$\, make
a list of all subsets $S$ of the set of degree-$d$ monomials such that $S
$ is the set of nonzero coefficients of an element of $I$. For each $d$\,
this set of subsets is a combinatorial object called a matroid. As $d$ var
ies\, the resulting sequence of matroids is called the tropicalization of
$I$.\n\nI will discuss some of the many questions one can ask about tropic
alizations of ideals\, and how they are related to some classical question
s in combinatorial algebraic geometry\, such as the classification of toru
s orbits on Hilbert schemes of points in $\\mathbb{C}^2$. Some unexpected
combinatorial objects appear: e.g. when studying tropicalizations of subsc
hemes of $\\mathbb{P}^1$\, one is led to Schur polynomials and binary neck
laces.\n
LOCATION:https://researchseminars.org/talk/agstanford/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chenyang Xu (MIT)
DTSTART;VALUE=DATE-TIME:20200522T180000Z
DTEND;VALUE=DATE-TIME:20200522T193000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/9
DESCRIPTION:Title: K-moduli of Fano varieties\nby Chenyang Xu (MIT) as part of Stanfor
d algebraic geometry seminar\n\n\nAbstract\nOne main theme of the algebrai
c K-stability theory of Fano varieties is to use it to construct moduli sp
aces of Fano varieties. This has once been beyond algebraic geometers’ i
magination\, but K-stability is proven to give the right framework. By no
w except the properness\, all other main ingredients have essentially been
established\, based on the recent development of our understanding of K-s
tability theory and other inputs. In this talk\, we will give an outline o
f the construction\, with the focus on the essential role that the new cha
racterisation of K-stability plays\, and its connection to minimal model p
rogram theory.\n
LOCATION:https://researchseminars.org/talk/agstanford/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Bhargav Bhatt (University of Michigan)
DTSTART;VALUE=DATE-TIME:20200605T190000Z
DTEND;VALUE=DATE-TIME:20200605T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/11
DESCRIPTION:Title: A p-adic Riemann-Hilbert functor and vanishing theorems\nby Bharga
v Bhatt (University of Michigan) as part of Stanford algebraic geometry se
minar\n\n\nAbstract\nI will discuss an ongoing project (joint with Jacob L
urie) aiming to construct a $p$-adic Riemann-Hilbert functor\, attaching c
oherent complexes to constructible sheaves (with coefficients in $\\mathbb
{F}_p$\, $\\mathbb{Z}_p$ or $\\mathbb{Q}_p$) on a compact algebraic variet
y over a $p$-adic field. When combined with results on constructible sheav
es\, these yields vanishing theorems (old and new) on the coherent side.\n
\nThe discussion for Bhargav Bhatt’s talk is taking place not in zoom-ch
at\, but at https://tinyurl.com/2020-06-05-bb (and will be deleted after
3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Wei Ho (University of Michigan)
DTSTART;VALUE=DATE-TIME:20200612T190000Z
DTEND;VALUE=DATE-TIME:20200612T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/12
DESCRIPTION:Title: Splitting Brauer classes\nby Wei Ho (University of Michigan) as pa
rt of Stanford algebraic geometry seminar\n\n\nAbstract\nGiven a Brauer cl
ass over a field\, what types of varieties split it? Or more geometrically
\, can we say anything about the varieties that map to a given Brauer-Seve
ri variety? In this talk\, we will discuss some open questions related to
splitting Brauer classes. For example\, we will review some classical alge
bro-geometric constructions that produce genus one curves splitting low in
dex Brauer classes ((old) joint work with A.J. de Jong)\, and we will expl
ain why a Brauer class of any index is split by a torsor under an abelian
variety (joint work with M. Lieblich).\n\nThe discussion for Wei Ho’s ta
lk is taking place not in zoom-chat\, but at https://tinyurl.com/2020-06-1
2-wh (and will be deleted after 3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yuchen Liu (Yale)
DTSTART;VALUE=DATE-TIME:20200529T174500Z
DTEND;VALUE=DATE-TIME:20200529T184500Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/13
DESCRIPTION:Title: Moduli spaces of quartic hyperelliptic K3 surfaces via K-stability
\nby Yuchen Liu (Yale) as part of Stanford algebraic geometry seminar\n\n\
nAbstract\nA general polarized hyperelliptic K3 surfaces of degree 4 is a
double cover of $\\mathbf{P\n}^ 1 \\times \\mathbf{P}^1$ branched along a
bidegree $(4\,4)$ curve. Classically there are two compactifications of th
eir moduli spaces: one is the GIT quotient of $(4\,4)$ curves\, the other
is the Baily-Borel compactification of their periods. We show that K-stabi
lity provides a natural modular interpolation between these two compactifi
cations. This provides a new aspect toward a recent result of Laza-O'Grady
. Based on joint work in progress with K. Ascher and K. DeVleming.\n\nThe
discussion for Yuchen Liu’s talk is taking place not in zoom-chat\, but
at https://tinyurl.com/2020-05-29-yl (and will be deleted after 3-7 days).
\n
LOCATION:https://researchseminars.org/talk/agstanford/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Margaret Bilu (NYU)
DTSTART;VALUE=DATE-TIME:20200612T174500Z
DTEND;VALUE=DATE-TIME:20200612T184500Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/14
DESCRIPTION:Title: Arithmetic and motivic statistics via zeta functions\nby Margaret
Bilu (NYU) as part of Stanford algebraic geometry seminar\n\n\nAbstract\nT
he Grothendieck group of varieties over a field $k$ is the quotient of the
free abelian group on isomorphism classes of algebraic varieties over k b
y the so-called cut-and-paste relations. Many results in number theory hav
e a natural motivic analogue which can be formulated in the Grothendieck r
ing of varieties. For example\, Poonen's finite field Bertini theorem has
a motivic counterpart due to Vakil and Wood\, though none of the two state
ments can be deduced from the other. We describe a conjectural way to unif
y the number-theoretic and motivic statements (when the base field is fini
te) in this and other examples\, and will provide some evidence towards it
. A key step is to reformulate everything in terms of convergence of zeta
functions of varieties in several different topologies. This is joint work
with Ronno Das and Sean Howe.\n
LOCATION:https://researchseminars.org/talk/agstanford/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:John Christian Ottem (University of Oslo)
DTSTART;VALUE=DATE-TIME:20200710T190000Z
DTEND;VALUE=DATE-TIME:20200710T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/15
DESCRIPTION:Title: On (2\,3)-fourfolds\nby John Christian Ottem (University of Oslo)
as part of Stanford algebraic geometry seminar\n\n\nAbstract\nI will expla
in how tropical degenerations and birational specialization techniques can
be used in rationality problems. In particular\, I will apply these techn
iques to study quartic fivefolds and complete intersections of a quadric a
nd a cubic in $\\mathbb{P}^6$. This is joint work with Johannes Nicaise.\n
LOCATION:https://researchseminars.org/talk/agstanford/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Laura Escobar (Washington University St. Louis)
DTSTART;VALUE=DATE-TIME:20200717T190000Z
DTEND;VALUE=DATE-TIME:20200717T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/16
DESCRIPTION:Title: Wall-crossing phenomena for Newton-Okounkov bodies\nby Laura Escob
ar (Washington University St. Louis) as part of Stanford algebraic geometr
y seminar\n\n\nAbstract\nA Newton-Okounkov body is a convex set associated
to a projective variety\, equipped with a valuation. These bodies general
ize the theory of Newton polytopes. Work of Kaveh-Manon gives an explicit
link between tropical geometry and Newton-Okounkov bodies. We use this lin
k to describe a wall-crossing phenomenon for Newton-Okounkov bodies. This
is joint work with Megumi Harada.\n\nThe discussion for Laura Escobar Vega
’s talk is taking place not in zoom-chat\, but at https://tinyurl.com/20
20-07-17-lev (and will be deleted after 3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Brendan Hassett (Brown University / ICERM)
DTSTART;VALUE=DATE-TIME:20200724T190000Z
DTEND;VALUE=DATE-TIME:20200724T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/17
DESCRIPTION:Title: Symbols\, birational geometry\, and computations\nby Brendan Hasse
tt (Brown University / ICERM) as part of Stanford algebraic geometry semin
ar\n\n\nAbstract\nWe are interested in G-birational equivalence of varieti
es where G is a finite group. Kontsevich-Tschinkel and Kresch-Tschinkel ha
ve developed symbol formalism to construct invariants that show rich inter
nal structure. We present examples of computations of these invariants for
varieties in small dimensions\, illustrating how they compare to existing
classification techniques.\n
LOCATION:https://researchseminars.org/talk/agstanford/17/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dan Abramovich (Brown University)
DTSTART;VALUE=DATE-TIME:20200731T193000Z
DTEND;VALUE=DATE-TIME:20200731T203000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/18
DESCRIPTION:Title: Resolution and logarithmic resolution via weighted blowings up [NOTE:
starts half an hour later than user]\nby Dan Abramovich (Brown Univer
sity) as part of Stanford algebraic geometry seminar\n\n\nAbstract\n[WARNI
NG: this talk starts a half hour after the seminar usually does!] \n\nT
his lecture combines resolution of singularities\, logarithmic geometry an
d algebraic stacks. I will not assume familiarity neither with resolution
of singularities nor with logarithmic geometry. I report on work with Temk
in and Wlodarczyk and work of Quek. Resolving singularities in families re
quires logarithmic geometry. Surprisingly\, trying to do this canonically
forces us to use stack-theoretic modifications. Surprisingly\, stack-theor
etic modifications provides an efficient iterative resolution method in wh
ich the worst singularities are blown up without regard to the history. No
t so surprisingly\, to make exceptional divisors cooperate we need logarit
hmic geometry again.\n\nThe discussion for Dan Abramovich’s talk is taki
ng place not in zoom-chat\, but at https://tinyurl.com/2020-07-31-da (and
will be deleted after 3-7 days).\n
LOCATION:
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hannah Larson (Stanford University)
DTSTART;VALUE=DATE-TIME:20200821T190000Z
DTEND;VALUE=DATE-TIME:20200821T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/19
DESCRIPTION:Title: Brill--Noether theory over the Hurwitz space\nby Hannah Larson (St
anford University) as part of Stanford algebraic geometry seminar\n\n\nAbs
tract\nLet $C$ be a curve of genus $g$. A fundamental problem in the theor
y of algebraic curves is to understand maps of $C$ to projective space of
dimension r of degree d. When the curve $C$ is general\, the moduli space
of such maps is well-understood by the main theorems of Brill-Noether theo
ry. However\, in nature\, curves $C$ are often encountered already equipp
ed with a map to some projective space\, which may force them to be specia
l in moduli. The simplest case is when $C$ is general among curves of fix
ed gonality. Despite much study over the past three decades\, a similarly
complete picture has proved elusive in this case. In this talk\, I will d
iscuss recent joint work with Eric Larson and Isabel Vogt that completes s
uch a picture\, by proving analogs of all of the main theorems of Brill--N
oether theory in this setting.\n\nThe discussion for Hannah Larson’s tal
k is taking place not in zoom-chat\, but at https://tinyurl.com/2020-08-21
-hl (and will be deleted after 3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/19/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Martin Olsson (UC Berkeley)
DTSTART;VALUE=DATE-TIME:20200828T190000Z
DTEND;VALUE=DATE-TIME:20200828T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/20
DESCRIPTION:Title: Determinants and deformation theory of perfect complexes\nby Marti
n Olsson (UC Berkeley) as part of Stanford algebraic geometry seminar\n\n\
nAbstract\nIn this talk I will discuss the interplay between the deformati
on theory of perfect complexes\, determinants\, and traces. I will discuss
\, in particular\, the verification of an expected compatibility among the
se that has been used in various places in the literature. For the speake
r this project also provided an entry-point to the world of $\\infty$-cate
gories\, and I will try to motivate why such a perspective is useful. Thi
s is joint work with Max Lieblich.\n\nThe discussion for Martin Olsson’s
talk is taking place not in zoom-chat\, but at https://tinyurl.com/2020-0
8-28-mo (and will be deleted after 3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/20/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rachel Webb (UC Berkeley)
DTSTART;VALUE=DATE-TIME:20200918T190000Z
DTEND;VALUE=DATE-TIME:20200918T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/21
DESCRIPTION:Title: Virtual cycle on the moduli space of maps to a complete intersection\nby Rachel Webb (UC Berkeley) as part of Stanford algebraic geometry se
minar\n\n\nAbstract\nA driving question in Gromov-Witten theory is to rela
te the invariants of a complete intersection to the invariants of the ambi
ent variety. In genus-zero this can often be done with a ``twisted theory\
,'' but this fails in higher genus. Several years ago\, Chang-Li presented
the moduli space of p-fields as a piece of the solution to the higher-gen
us problem\, constructing the virtual cycle on the space of maps to the qu
intic 3-fold as a cosection localized virtual cycle on a larger moduli spa
ce (the space of p-fields). Their result is analogous to the classical sta
tement that the Euler class of a vector bundle is the class of the zero lo
cus of a generic section. I will discuss work joint with Qile Chen and Fel
ix Janda where we extend Chang-Li's result to a more general setting\, a s
etting that includes standard Gromov-Witten theory of smooth orbifold targ
ets and quasimap theory of GIT targets.\n
LOCATION:https://researchseminars.org/talk/agstanford/21/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Chris Eur (Stanford)
DTSTART;VALUE=DATE-TIME:20200904T190000Z
DTEND;VALUE=DATE-TIME:20200904T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/22
DESCRIPTION:Title: Simplicial generation of Chow rings of matroids\nby Chris Eur (Sta
nford) as part of Stanford algebraic geometry seminar\n\n\nAbstract\nWe pr
esent a new set of generators for the Chow ring of a matroid. We show tha
t these generators behave like base-point-free divisors by establishing th
at (i) they correspond to matroid operations that combinatorially mirror h
yperplane pullbacks\, and (ii) the volume polynomial with respect to these
generators satisfies Hodge-type inequalities. We thereby generalize Post
nikov's results on generalized permutohedra\, and also give a simplified p
roof of the combinatorially relevant portion of the Hodge theory of matroi
ds developed by Adiprasito-Huh-Katz. No knowledge of matroids will be ass
umed. This is joint work with Spencer Backman and Connor Simpson.\n\nThe
discussion for Christopher Eur’s talk is taking place not in zoom-chat\,
but at https://tinyurl.com/2020-09-04-ce (and will be deleted after 3-7
days).\n
LOCATION:https://researchseminars.org/talk/agstanford/22/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andrew Kobin (UC Santa Cruz)
DTSTART;VALUE=DATE-TIME:20200911T190000Z
DTEND;VALUE=DATE-TIME:20200911T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/23
DESCRIPTION:Title: Zeta functions and decomposition spaces\nby Andrew Kobin (UC Santa
Cruz) as part of Stanford algebraic geometry seminar\n\n\nAbstract\nZeta
functions show up everywhere in math these days. While some recent work ha
s brought homotopical methods into the theory of zeta functions\, there is
in fact a lesser-known zeta function that is native to homotopy theory. N
amely\, every suitably finite decomposition space (aka 2-Segal space) admi
ts an abstract zeta function as an element of its incidence algebra. In th
is talk\, I will show how many 'classical' zeta functions from number theo
ry and algebraic geometry can be realized in this homotopical framework\,
and outline some preliminary work in progress with Julie Bergner and Matt
Feller towards a motivic version of the above story.\n\nThe discussion for
Andrew Kobin’s talk is taking place not in zoom-chat\, but at https://t
inyurl.com/2020-09-11-ak (and will be deleted after 3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/23/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Richard Thomas (Imperial College London)
DTSTART;VALUE=DATE-TIME:20200925T190000Z
DTEND;VALUE=DATE-TIME:20200925T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/24
DESCRIPTION:Title: Square root Euler classes and counting sheaves on Calabi-Yau 4-folds\nby Richard Thomas (Imperial College London) as part of Stanford algebr
aic geometry seminar\n\n\nAbstract\nI will explain a nice characteristic c
lass of $SO(2n\,\\mathbf{C})$ bundles in both Chow cohomology and K-theory
\, and how to localise it to the zeros of an isotropic section. This build
s on work of Edidin-Graham\, Polishchuk-Vaintrob\, Anderson and many other
s.\n\nThis can be used to construct an algebraic virtual cycle (and virtua
l structure sheaf) on moduli spaces of stable sheaves on Calabi-Yau 4-fold
s.\nIt recovers the real derived differential geometry virtual cycle of Bo
risov-Joyce but has nicer properties\, like a torus localisation formula.
Joint work with Jeongseok Oh (KIAS).\n\nThe discussion for Richard Thomas
’s talk is taking place not in zoom-chat\, but at https://tinyurl.com/20
20-09-25-rt (and will be deleted after 3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/24/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jarod Alper (University of Washington)
DTSTART;VALUE=DATE-TIME:20201023T190000Z
DTEND;VALUE=DATE-TIME:20201023T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/25
DESCRIPTION:Title: Coherent completeness and the local structure of algebraic stacks\
nby Jarod Alper (University of Washington) as part of Stanford algebraic g
eometry seminar\n\n\nAbstract\nFormal GAGA is an important theorem in form
al geometry which categorizes coherent sheaves on a scheme proper over a c
omplete local noetherian ring in terms of compatible families of coherent
sheaves on the thickenings of its central fiber. We will discuss generali
zations of this result to algebraic stacks and explain how such results ca
n be used to prove local structure theorems for algebraic stacks. After r
eviewing joint work with Hall and Rydh which establishes a satisfactory re
sult in characteristic 0\, we will discuss partial progress in joint work
with Hall and Lim on extending this result to positive characteristic.\n\n
The discussion for Jarod Alper’s talk is taking place not in zoom-chat\,
but at https://tinyurl.com/2020-10-23-ja (and will be deleted after ~3-7
days).\n
LOCATION:https://researchseminars.org/talk/agstanford/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Aaron Landesman (Stanford)
DTSTART;VALUE=DATE-TIME:20201030T190000Z
DTEND;VALUE=DATE-TIME:20201030T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/26
DESCRIPTION:Title: The Torelli map restricted to the hyperelliptic locus\nby Aaron La
ndesman (Stanford) as part of Stanford algebraic geometry seminar\n\n\nAbs
tract\nThe classical Torelli theorem states that the Torelli map\, sending
a curve to\nits Jacobian\, is injective on points. However\, the Torelli
map is not injective \non tangent spaces at points corresponding to hypere
lliptic curves. This leads to\nthe natural question: If one restricts the
Torelli map to the locus of\nhyperelliptic curves\, is it then an immersio
n?\n\nWe give a complete answer to this question\, starting out by describ
ing the\nclassical history and several surprising foundational gaps in the
\nliterature. Along the way\, we will learn about Shinichi Mochizuki's val
uative\ncriterion for locally closed immersions and its relation to Brian
Conrad's\nlibrary app idea.\n\nThe discussion for Aaron Landesman’s talk
is taking place not in zoom-chat\, but at https://tinyurl.com/2020-10-3
0-al (and will be deleted after ~3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/26/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Juliette Bruce (UC Berkeley)
DTSTART;VALUE=DATE-TIME:20201002T190000Z
DTEND;VALUE=DATE-TIME:20201002T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/27
DESCRIPTION:Title: The top weight cohomology of $A_g$\nby Juliette Bruce (UC Berkeley
) as part of Stanford algebraic geometry seminar\n\n\nAbstract\nI will dis
cuss recent work calculating the top weight cohomology of the moduli space
$A_g$ of principally polarized abelian varieties of dimension $g$ for sma
ll values of $g$. The key idea is that this piece of cohomology is encoded
combinatorially via the relationship between the boundary complex of a co
mpactification of $A_g$ and the moduli space of tropical abelian varieties
. This is joint work with Madeline Brandt\, Melody Chan\, Margarida Melo\,
Gwyneth Moreland\, and Corey Wolfe.\n
LOCATION:https://researchseminars.org/talk/agstanford/27/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ben Antieau (Northwestern)
DTSTART;VALUE=DATE-TIME:20210115T200000Z
DTEND;VALUE=DATE-TIME:20210115T210000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/28
DESCRIPTION:Title: Genus 1 curves in twisted projective spaces\nby Ben Antieau (North
western) as part of Stanford algebraic geometry seminar\n\n\nAbstract\nDoe
s every Severi—Brauer variety contain a (possibly singular) genus 1 curv
e? This basic question was asked by David Saltman and Pete Clark and answe
red in low dimensions by Johan de Jong and Wei Ho. I will explain somethin
g of the history of the problem as well as recent joint work with Asher Au
el where we show\, with the help of a nice observation of David Saltman\,
that the answer is `yes’ for twisted forms of $\\mathbb{P}^r$ for $r=6$
over global fields.\n\nThe discussion for Ben Antieau’s talk is taking p
lace not in zoom-chat\, but at https://tinyurl.com/2021-01-15-ba (and wi
ll be deleted after ~3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/28/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Karen Smith (University of Michigan)
DTSTART;VALUE=DATE-TIME:20201009T190000Z
DTEND;VALUE=DATE-TIME:20201009T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/29
DESCRIPTION:Title: Extremal Singularities in Prime Characteristic\nby Karen Smith (Un
iversity of Michigan) as part of Stanford algebraic geometry seminar\n\n\n
Abstract\nWhat is the most singular possible singularity? What can we say
about its geometric and algebraic properties? This seemingly naive questio
n has a sensible answer in characteristic $p$.\nThe "F-pure threshold\," w
hich is an analog of the log canonical threshold\, can be used to "measur
e" how bad a singularity is. The F-pure threshold is a numerical invariant
of a point on (say) a hypersurface---a positive rational number that is
1 at any smooth point (or more generally\, any F-pure point) but less tha
n one in general\, with "more singular" points having smaller F-pure thres
holds. We explain a recently proved lower bound on the F-pure threshold i
n terms of the multiplicity of the singularity. We also show that there is
a nice class of hypersurfaces---which we call "Extremal hypersurfaces"---
for which this bound is achieved. These have very nice (extreme!) geometri
c properties. For example\, the affine cone over a non Frobenius split cub
ic surface of characteristic two is one example of an "extremal singularit
y". Geometrically\, these are the only cubic surfaces with the property th
at *every* triple of coplanar lines on the surface meets in a single point
(rather than a "triangle" as expected)---a very extreme property indeed.\
n\nThe discussion for Karen Smith’s talk is taking place not in zoom-cha
t\, but at https://tinyurl.com/2020-10-09-ks (and will be deleted after ~
3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/29/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Barbara Fantechi (SISSA)
DTSTART;VALUE=DATE-TIME:20201016T190000Z
DTEND;VALUE=DATE-TIME:20201016T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/30
DESCRIPTION:Title: Infinitesimal deformations of semi-smooth varieties\nby Barbara Fa
ntechi (SISSA) as part of Stanford algebraic geometry seminar\n\n\nAbstrac
t\nThis is a report on joint work with Marco Franciosi and Rita Pardini. G
eneralizing the standard definition for surfaces\, we call a variety $X$ (
over an alg closed field of char not 2) {\\em semi-smooth} if its singular
ities are \\'etale locally either $uv=0$ or $u^2=v^2w$ (pinch point)\; equ
ivalently\, if $X$ can be obtained by gluing a smooth variety (the normali
zation of $X$) along an involution (with smooth quotient) on a smooth divi
sor. They are the simplest singularities for non normal\, KSBA-stable surf
aces.\nFor a semi-smooth variety $X$\, we calculate the tangent sheaf $T_X
$ and the infinitesimal deformations sheaf ${\\mathcal T}^1_X:={\\mathcal
E}xt^1(\\Omega_X\,\\mathcal O_X)$ which determine the infinitesimal deform
ations and smoothability of $X$.\nAs an application\, we use Tziolas' form
al smoothability criterion to show that every stable semi-smooth Godeaux s
urface (classified by Franciosi\, Pardini and S\\"onke) corresponds to a s
mooth point of the KSBA moduli space\, in the closure of the open locus of
smooth surfaces.\n\nThe discussion for Barbara Fantechi’s talk is takin
g place not in zoom-chat\, but at https://tinyurl.com/2020-10-16-bf (and
will be deleted after ~3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/30/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Akhil Mathew (University of Chicago)
DTSTART;VALUE=DATE-TIME:20201106T200000Z
DTEND;VALUE=DATE-TIME:20201106T210000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/31
DESCRIPTION:Title: \\'Etale K-theory and motivic cohomology\nby Akhil Mathew (Univers
ity of Chicago) as part of Stanford algebraic geometry seminar\n\n\nAbstra
ct\nTwo key features of algebraic K-theory are its failure to\nsatisfy \\'
etale descent\, and its motivic filtration in terms of higher\nChow groups
in the case of smooth schemes over a field (but expected\nmore generally)
. I will explain a description of \\'etale K-theory\,\nwhich is the univer
sal approximation to K-theory that satisfies\n\\'etale descent\; this is j
oint work with Dustin Clausen. Moreover\,\nfollowing the recent work of Bh
att--Morrow--Scholze on topological\ncyclic homology\, I will also explain
a construction of (an analog of)\nthe motivic filtration on \\'etale K-th
eory (and \\'etale motivic\ncohomology) for arbitrary schemes (work in pro
gress with Bhargav Bhatt\nand Dustin Clausen).\n\nThe discussion for Akhil
Mathew’s talk is taking place not in zoom-chat\, but at https://tinyu
rl.com/2020-11-06-am (and will be deleted after ~3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/31/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Taylor Dupuy (University of Vermont)
DTSTART;VALUE=DATE-TIME:20201113T200000Z
DTEND;VALUE=DATE-TIME:20201113T210000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/32
DESCRIPTION:Title: Abelian Varieties Over Finite Fields in the LMFDB\nby Taylor Dupuy
(University of Vermont) as part of Stanford algebraic geometry seminar\n\
n\nAbstract\nI will talk about things around the LMFDB database of isogeny
classes of abelian varieties over finite fields (and maybe even about iso
morphism classes). \n\nThese could include: \n--"Sato-Ain't" distributions
\, \n--weird Tate classes\, \n--Bizzaro Hodge co-levels (and very strange
Ax-Katz/Chevalley-Warning type congruences with fractional exponent!)\, \n
--the counter-example to the conjecture of Ahmadi-Shparlinski\,\n--what we
know about angle ranks vs galois groups vs Newton polygons\,\n--new conje
ctures \n\nThe database and "census" is joint work with Kiran Kedlaya\, Da
vid Roe\, and Christelle Vincent (currently available on the arxiv). The w
ork on Tate classes is ongoing with Kiran Kedlaya and David Zureick-Brown.
\n\nThe discussion for Taylor Dupuy’s talk is taking place not in zoom-c
hat\, but at https://tinyurl.com/2020-11-13-td (and will be deleted afte
r ~3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/32/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Rahul Pandharipande (ETH Zurich)
DTSTART;VALUE=DATE-TIME:20201204T200000Z
DTEND;VALUE=DATE-TIME:20201204T210000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/33
DESCRIPTION:Title: The top Chern class of the Hodge bundle and the log Chow ring of the m
oduli space of curves\nby Rahul Pandharipande (ETH Zurich) as part of
Stanford algebraic geometry seminar\n\n\nAbstract\nI will first explain ho
w the top Chern class of the Hodge bundle is very complicated and then\nI
will explain how it is very simple. Joint work with S. Molcho and J. Schmi
tt.\n\nThe discussion for Rahul Pandharipande’s talk is taking place not
in zoom-chat\, but at https://tinyurl.com/2020-12-04-rp (and will be de
leted after ~3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/33/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Takumi Murayama (Princeton University)
DTSTART;VALUE=DATE-TIME:20210122T200000Z
DTEND;VALUE=DATE-TIME:20210122T210000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/34
DESCRIPTION:Title: Grothendieck's localization problem\nby Takumi Murayama (Princeton
University) as part of Stanford algebraic geometry seminar\n\n\nAbstract\
nLet $f\\colon Y \\rightarrow X$ be a proper flat morphism of algebraic v
arieties. Grothendieck and Dieudonné showed that the smoothness of $f$ ca
n be detected at closed points of $X$. Using André–Quillen homology\, A
ndré showed that when $X$ is excellent\, the same conclusion holds when $
f$ is a closed flat morphism between locally noetherian schemes. We give a
new proof of André's result using a version of resolutions of singularit
ies due to Gabber. Our method gives a uniform treatment of Grothendieck's
localization problem and resolves various new cases of this problem\, whic
h asks whether similar statements hold for other local properties of morph
isms.\n\nThe discussion for Takumi Murayama’s talk is taking place not i
n zoom-chat\, but at https://tinyurl.com/2021-01-22-tm (and will be delet
ed after ~3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/34/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Soumya Sankar (The Ohio State University)
DTSTART;VALUE=DATE-TIME:20210129T200000Z
DTEND;VALUE=DATE-TIME:20210129T210000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/35
DESCRIPTION:Title: Derived equivalences of gerbey curves\nby Soumya Sankar (The Ohio
State University) as part of Stanford algebraic geometry seminar\n\n\nAbst
ract\nThe question of whether derived equivalences determine a variety has
been studied widely. Antieau\, Krashen and Ward (AKW) studied the questio
n of when two genus 1 curves are derived equivalent. A gerbey curve is a G
_m gerbe over a usual curve. In joint work with Libby Taylor\, we explore
the question of when two gerbey genus 1 curves are derived equivalent. In
this talk\, I will give some background on derived equivalences of varieti
es\, how they relate to derived equivalences of stacks and then talk about
some extensions of the results of AKW.\n\nThe discussion for Soumya Sanka
r’s talk is taking place not in zoom-chat\, but at https://tinyurl.com/2
021-01-29-ss (and will be deleted after ~3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/35/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Sean Keel (UT Austin)
DTSTART;VALUE=DATE-TIME:20210205T200000Z
DTEND;VALUE=DATE-TIME:20210205T210000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/36
DESCRIPTION:Title: Berkovich geometry and mirror symmetry\nby Sean Keel (UT Austin) a
s part of Stanford algebraic geometry seminar\n\n\nAbstract\nI will explai
n my Berkovich geometric construction\, joint with Tony Yu\, of the mirror
to an affine log CY variety\, with the aim of convincing you of its simpl
icity\, both in concept\, and technical detail.\n\nThe discussion for Sean
Keel’s talk is taking place not in zoom-chat\, but at https://tinyurl.c
om/2021-02-05-sk (and will be deleted after ~3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/36/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Laure Flapan (Michigan State)
DTSTART;VALUE=DATE-TIME:20210212T200000Z
DTEND;VALUE=DATE-TIME:20210212T210000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/37
DESCRIPTION:Title: Fano manifolds associated to hyperkähler manifolds\nby Laure Flap
an (Michigan State) as part of Stanford algebraic geometry seminar\n\n\nAb
stract\nMany of the known examples of hyperkähler manifolds arise from ge
ometric constructions that begin with a Fano manifold whose cohomology loo
ks like that of a K3 surface. In this talk\, I will focus on a program who
se goal is to reverse this process\, namely to begin with a hyperkähler m
anifold and from it produce geometrically a Fano manifold. This is joint w
ork in progress with K. O’Grady\, E. Macrì\, and G. Saccà.\n\nThe disc
ussion for Laure Flapan’s talk is taking place not in zoom-chat\, but at
https://tinyurl.com/2021-02-12-lf (and will be deleted after ~3-7 days)
.\n
LOCATION:https://researchseminars.org/talk/agstanford/37/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Izzet Coskun (University of Illinois at Chicago)
DTSTART;VALUE=DATE-TIME:20210219T200000Z
DTEND;VALUE=DATE-TIME:20210219T210000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/38
DESCRIPTION:Title: Algebraic Hyperbolicity and Lang-type loci in hypersurfaces\nby Iz
zet Coskun (University of Illinois at Chicago) as part of Stanford algebra
ic geometry seminar\n\n\nAbstract\nIn this talk\, I will discuss joint wor
k with Eric Riedl on algebraic hyperbolicity and Lang-type loci. I will de
scribe an improvement of G. Xu's genus bounds which allow us to prove the
algebraic hyperbolicity of very general quintic surfaces. The same techniq
ue allows us to obtain the classification of algebraically hyperbolic sur
faces in certain toric threefolds. Finally\, I will discuss Lang-type loci
for algebraic hyperbolicity in very general hypersurfaces.\n\nThe discuss
ion for Izzet Coskun’s talk is taking place not in zoom-chat\, but at h
ttps://tinyurl.com/2021-02-19-ic (and will be deleted after ~3-7 days).\n
LOCATION:https://researchseminars.org/talk/agstanford/38/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Matt Baker (Georgia Tech)
DTSTART;VALUE=DATE-TIME:20210402T190000Z
DTEND;VALUE=DATE-TIME:20210402T200000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/39
DESCRIPTION:by Matt Baker (Georgia Tech) as part of Stanford algebraic geo
metry seminar\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/agstanford/39/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Jihao Liu (University of Utah)
DTSTART;VALUE=DATE-TIME:20210226T200000Z
DTEND;VALUE=DATE-TIME:20210226T210000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/40
DESCRIPTION:Title: Complements and local singularities in birational geometry\nby Jih
ao Liu (University of Utah) as part of Stanford algebraic geometry seminar
\n\n\nAbstract\nThe theory of complements was introduced by Shokurov when
he investigated log flips of threefolds\, and plays an important role in m
any areas in birational geometry\, e.g. boundedness of Fano varieties\, lo
g Calabi-Yau fibrations\, K-stability theory\, etc. In a recent work\, we
prove a complements conjecture of Shokurov\, and we apply this result to t
he study of local singularities in birational geometry. Part of this talk
is joint work with J. Han and V.V. Shokurov.\n
LOCATION:https://researchseminars.org/talk/agstanford/40/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Arend Bayer (University of Edinburgh)
DTSTART;VALUE=DATE-TIME:20210305T200000Z
DTEND;VALUE=DATE-TIME:20210305T210000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/41
DESCRIPTION:by Arend Bayer (University of Edinburgh) as part of Stanford a
lgebraic geometry seminar\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/agstanford/41/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yuuji Tanaka (Kyoto University)
DTSTART;VALUE=DATE-TIME:20210313T000000Z
DTEND;VALUE=DATE-TIME:20210313T010000Z
DTSTAMP;VALUE=DATE-TIME:20210225T125359Z
UID:agstanford/42
DESCRIPTION:Title: On the virtual Euler characteristics of the moduli spaces of semistab
le sheaves on a complex projective surface\nby Yuuji Tanaka (Kyoto Uni
versity) as part of Stanford algebraic geometry seminar\n\n\nAbstract\n(wa
rning: notice unusual time)\n\nI'll deliver an overview of studies on the
virtual Euler \ncharacteristics of the moduli spaces of semistable sheave
s on a complex \nprojective surface. The virtual Euler characteristic is a
refinement of \nthe topological Euler characteristic for a proper scheme
with a perfect \nobstruction theory，which was introduced by Fantechi and
Goettsche\, and \nby Ciocan-Fontanine and Kapranov. Motivated by the work
of Vafa and \nWitten in the early 90's on the S-duality conjecture in N=4
super \nYang-Mills theory in physics\, Goettsche and Kool conjectured tha
t the \ngenerating function of the virtual Euler characteristics\, or othe
r \nvariants\, of the moduli space of semistable sheaves on a complex \npr
ojective surfaces could be written in terms of modular forms (and the \nSe
iberg-Witten invariants)\, and they verified it in examples. I'll \ndescri
be the recent progress around this topic\, starting by mentioning \nmore b
ackground materials such as the studies on the topological Euler \ncharact
eristics of the moduli spaces.\n
LOCATION:https://researchseminars.org/talk/agstanford/42/
END:VEVENT
END:VCALENDAR