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BEGIN:VEVENT
SUMMARY:Jigu Kim (Postech)
DTSTART:20250320T070000Z
DTEND:20250320T080000Z
DTSTAMP:20260404T095121Z
UID:Postech-PMI-NT/1
DESCRIPTION:Title: Genus character L-functions and their applications\nby J
igu Kim (Postech) as part of Postech-PMI Number Theory Seminar\n\nLecture
held in Room 404.\n\nAbstract\nWe introduce the general genus character fo
r two distinct (not necessarily relatively prime) discriminants of quadrat
ic fields. We provide an explicit formula for the genus character L-functi
on of a quadratic order\, along with two different proofs. As applications
\, we generalize the Hirzebruch-Zagier formula for the class numbers of im
aginary quadratic fields and investigate congruences between Hirzebruch su
ms and class numbers modulo powers of two. This is joint work with Yoshino
ri Mizuno.\n
LOCATION:https://stable.researchseminars.org/talk/Postech-PMI-NT/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniel Disegni (Université d'Aix-Marseille)
DTSTART:20250327T080000Z
DTEND:20250327T090000Z
DTSTAMP:20260404T095121Z
UID:Postech-PMI-NT/2
DESCRIPTION:Title: Gan-Gross-Prasad cycles and derivatives of p-adic L-function
s\nby Daniel Disegni (Université d'Aix-Marseille) as part of Postech-
PMI Number Theory Seminar\n\n\nAbstract\nCertain Rankin-Selberg motives of
rank n(n+1) are endowed with algebraic cycles arising from maps of unitar
y Shimura varieties. Gan-Gross-Prasad conjectured that these cycles are an
alogous to Heegner points\, in the sense that their nontriviality should b
e detected by derivatives of L-functions.\n\nI will discuss another nontri
viality criterion\, based on p-adic L-functions. Under some local conditio
ns\, this variant can be established in a refined quantitative form\, via
the construction and comparison of two p-adic relative-trace formulas. (Jo
int work with Wei Zhang.)\n
LOCATION:https://stable.researchseminars.org/talk/Postech-PMI-NT/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Wanlin Li (Washington University in St. Louis)
DTSTART:20250403T000000Z
DTEND:20250403T010000Z
DTSTAMP:20260404T095121Z
UID:Postech-PMI-NT/3
DESCRIPTION:Title: Non-vanishing of Ceresa and Gross--Kudla--Schoen cycles\
nby Wanlin Li (Washington University in St. Louis) as part of Postech-PMI
Number Theory Seminar\n\n\nAbstract\nThe Ceresa cycle and the Gross—Kudl
a—Schoen modified diagonal cycle are algebraic 1-cycles associated to a
smooth algebraic curve. They are algebraically trivial for a hyperelliptic
curve and non-trivial for a very general complex curve of genus >2. Given
an algebraic curve\, it is an interesting question to study whether the C
eresa and GKS cycles associated to it are rationally or algebraically triv
ial. In this talk\, I will discuss some methods and tools to study this pr
oblem.\n
LOCATION:https://stable.researchseminars.org/talk/Postech-PMI-NT/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Karol Koziol (Baruch College\, City University of New York)
DTSTART:20250515T000000Z
DTEND:20250515T010000Z
DTSTAMP:20260404T095121Z
UID:Postech-PMI-NT/4
DESCRIPTION:Title: Derived Satake morphisms in characteristic p\nby Karol K
oziol (Baruch College\, City University of New York) as part of Postech-PM
I Number Theory Seminar\n\n\nAbstract\nThe classical Satake transform give
s an isomorphism between the complex spherical Hecke algebra of a p-adic r
eductive group G\, and the Weyl-invariants of the complex spherical Hecke
algebra of a maximal torus of G. This provides a way for understanding the
K-invariant vectors in smooth irreducible complex representations of G (w
here K is a maximal compact subgroup of G)\, and allows one to construct i
nstances of unramified Langlands correspondences. In this talk\, I'll pres
ent joint work with Cédric Pépin in which we attempt to understand the a
nalogous situation with mod p coefficients\, and working at the level of t
he derived category of smooth G-representations.\n
LOCATION:https://stable.researchseminars.org/talk/Postech-PMI-NT/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Myungjun Yu (Yonsei University)
DTSTART:20250605T070000Z
DTEND:20250605T080000Z
DTSTAMP:20260404T095121Z
UID:Postech-PMI-NT/5
DESCRIPTION:Title: The distribution of the cokernel of a random p-adic matrix\nby Myungjun Yu (Yonsei University) as part of Postech-PMI Number Theor
y Seminar\n\nLecture held in Room 404.\n\nAbstract\nThe cokernel of a rand
om p-adic matrix can be used to study the distribution of objects that ari
se naturally in number theory. For example\, Cohen and Lenstra suggested a
conjectural distribution of the p-parts of the ideal class groups of imag
inary quadratic fields. Friedman and Washington proved that the distributi
on of the cokernel of a random p-adic matrix is the same as the Cohen–Le
nstra distribution. Recently\, Wood generalized the result of Friedman–W
ashington by considering a far more general class of measure on p-adic mat
rices. In this talk\, we explain a further generalization of Wood’s work
. This is joint work with Dong Yeap Kang and Jungin Lee.\n
LOCATION:https://stable.researchseminars.org/talk/Postech-PMI-NT/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yong-Gyu Choi (KAIST)
DTSTART:20250501T070000Z
DTEND:20250501T080000Z
DTSTAMP:20260404T095121Z
UID:Postech-PMI-NT/6
DESCRIPTION:Title: On degeneration of D-shtukas over ramified legs\nby Yong
-Gyu Choi (KAIST) as part of Postech-PMI Number Theory Seminar\n\nLecture
held in Room 404.\n\nAbstract\nThe canonical integral models of Shimura va
rieties associated with reductive groups that are anisotropic modulo cente
r are expected to be proper. However\, an analogous property is known to b
e false for the moduli stack of shtukas over global function fields. More
precisely\, given a proper smooth curve X over a finite field and a paraho
ric group scheme G over X corresponding to a maximal order of a central di
vision algebra D over the function field of X\, Eike Lau obtained a numeri
cal criterion for the properness of the moduli stack of bounded G-shtukas
with legs in the split locus of D. As a consequence\, there exists an inst
ance where the moduli stack of bounded G-shtukas is not proper over the sp
lit locus of D.\n\nBased on the work of Arasteh Rad—Hartl and Bieker\, t
he moduli stack of bounded G-shtukas is allowed to have legs in the ramifi
cation locus of D. We extend Lau's result to the case where the legs are a
llowed to lie in the ramification locus\, showing in particular that the m
oduli stack of G-shtukas can be proper when the legs are restricted to the
split locus of D\, but not proper when the legs run over the whole curve.
This is joint work with Wansu Kim and Junyeong Park.\n
LOCATION:https://stable.researchseminars.org/talk/Postech-PMI-NT/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yu Luo (University of Wisconsin–Madison)
DTSTART:20250904T000000Z
DTEND:20250904T010000Z
DTSTAMP:20260404T095121Z
UID:Postech-PMI-NT/7
DESCRIPTION:Title: A new proof of the arithmetic Siegel-Weil formula\nby Yu
Luo (University of Wisconsin–Madison) as part of Postech-PMI Number The
ory Seminar\n\n\nAbstract\nThe arithmetic Siegel-Weil formula establishes
a profound connection between intersection numbers in Shimura varieties an
d the Fourier coefficients of central derivatives of Eisenstein series. Th
is result was proven by C. Li and W. Zhang in 2021 using local methods. In
this talk\, I will present a new proof of the formula that uses the local
-global compatibility and the modularity of generating series of special d
ivisors.\n
LOCATION:https://stable.researchseminars.org/talk/Postech-PMI-NT/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ryan Chen (Princeton University)
DTSTART:20250925T000000Z
DTEND:20250925T010000Z
DTSTAMP:20260404T095121Z
UID:Postech-PMI-NT/8
DESCRIPTION:Title: Near-center derivatives and arithmetic 1-cycles\nby Ryan
Chen (Princeton University) as part of Postech-PMI Number Theory Seminar\
n\n\nAbstract\nTheta series for lattices count lattice vectors of fixed no
rm. Such theta series give some of the first examples of automorphic forms
.\n\nIt is possible to form "theta series" in other geometric contexts\, e
.g. for counting problems involving abelian varieties.\nIt is expected tha
t these theta series again have additional automorphic symmetry.\n\nI will
explain some “near-central” instances of an arithmetic Siegel--Weil f
ormula from Kudla’s program. These "geometrize" the classical Siegel--We
il formulas\, on lattice and lattice vector counting via Eisenstein series
.\n\nAt these near-central points of functional symmetry\, we observe that
both the "leading" special value (complex volumes) and the "subleading" f
irst derivative (arithmetic volume) simultaneously have geometric meaning.
\n\nThe key input is a new "limit phenomenon" relating positive characteri
stic intersection numbers and heights in mixed characteristic\, as well as
its automorphic counterpart.\n
LOCATION:https://stable.researchseminars.org/talk/Postech-PMI-NT/8/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Hyuk Jun Kweon (Seoul National University)
DTSTART:20251120T070000Z
DTEND:20251120T080000Z
DTSTAMP:20260404T095121Z
UID:Postech-PMI-NT/9
DESCRIPTION:Title: On the p-adic Group Cohomology of Finite Group Schemes\n
by Hyuk Jun Kweon (Seoul National University) as part of Postech-PMI Numbe
r Theory Seminar\n\nLecture held in Room 404.\n\nAbstract\nWe introduce a
cohomology theory for finite group schemes with commutative formal groups
as coefficients. Using Fontaine's Witt covectors\, this theory provides a
p-adic cohomology theory for finite group schemes and is motivated by the
failure of étale cohomology to detect inseparable extensions. We define a
G-module structure on commutative formal group schemes and prove that the
ir category forms a Grothendieck category\, so it has enough injectives. W
e show that\, with Witt covectors as coefficients\, the derived functors o
f the invariants functor coincide with the cohomology computed via the bar
resolution. As an application\, we identify the first cohomology of a fin
ite commutative p-group scheme G with its Dieudonné module.\n
LOCATION:https://stable.researchseminars.org/talk/Postech-PMI-NT/9/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Heejong Lee (KIAS)
DTSTART:20251113T070000Z
DTEND:20251113T080000Z
DTSTAMP:20260404T095121Z
UID:Postech-PMI-NT/10
DESCRIPTION:Title: Families of mod p local Galois representations\nby Heej
ong Lee (KIAS) as part of Postech-PMI Number Theory Seminar\n\nLecture hel
d in Room 404.\n\nAbstract\nProblems in Number Theory are often reduced to
local problems. Here\, local means focusing on one prime number p (e.g. s
olving polynomials modulo p)\, as opposed to all prime numbers. The p-adic
numbers were introduced in 1897 as a new foundation to study local proble
ms in Number Theory. \n\nIn this talk\, I will introduce local Galois grou
ps and their representations. They play a key role in understanding congru
ence phenomenon in the Langlands program\, which already appeared in the w
ork of Wiles on Fermat's Last Theorem. I will explain how to study these o
bjects geometrically. In turn\, this suggests a intriguing connection to t
he representation theory of finite groups of Lie type. I will explain why
this is a shadow of a bigger picture—the mod p local Langlands program
—and discuss my results in this direction.\n
LOCATION:https://stable.researchseminars.org/talk/Postech-PMI-NT/10/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Stefano Marseglia (Université Côte d'Azur)
DTSTART:20251030T070000Z
DTEND:20251030T080000Z
DTSTAMP:20260404T095121Z
UID:Postech-PMI-NT/11
DESCRIPTION:Title: Singular ideals in orders\nby Stefano Marseglia (Univer
sité Côte d'Azur) as part of Postech-PMI Number Theory Seminar\n\n\nAbst
ract\nIn this talk\, we introduce the notion of multiplicator ladder of an
order in a product of number fields. Examples of orders admitting such a
structure are quadratic orders\, or\, more generally\, Bass orders. If an
order has a multiplicator ladder then the lattice of inclusions of its ove
rorders is rigidly structured. We prove this result\, use it to recover a
recent Theorem of Cho-Hong-Lee\, and if time permits\, we discuss an appli
cation to the theory of abelian varieties over finite fields and their iso
geny graphs.\n
LOCATION:https://stable.researchseminars.org/talk/Postech-PMI-NT/11/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Joseph Muller (NCTS\, National Taiwan University)
DTSTART:20260312T070000Z
DTEND:20260312T080000Z
DTSTAMP:20260404T095121Z
UID:Postech-PMI-NT/12
DESCRIPTION:Title: Bruhat-Tits stratification for the GU(1\,n-1) Shimura varie
ty with parahoric reduction over an inert prime\nby Joseph Muller (NCT
S\, National Taiwan University) as part of Postech-PMI Number Theory Semin
ar\n\n\nAbstract\nThe basic locus of certain Shimura varieties is known to
be stratified by (classical) Deligne-Lusztig varieties. Such a stratifica
tion is usually called the Bruhat-Tits stratification\, because the incide
nce relation is expected to be determined by the Bruhat-Tits building of s
ome related p-adic group. By the work of Görtz-He-Nie on affine Deligne-L
usztig varieties\, we know precisely which Shimura varieties must admit a
Bruhat-Tits stratification. However\, determining the actual incidence rel
ations usually requires a case-by-case analysis.\nIn this talk\, we consid
er PEL unitary Shimura varieties of signature (1\,n-1) over an inert prime
. For these varieties\, so far the Bruhat-Tits stratification had only bee
n described for hyperspecial level (Vollaard-Wedhorn) and maximal parahori
c level (Cho). Building upon these works\, we describe the stratification
for arbitrary parahoric levels. If time permits\, we will discuss how the
Bruhat-Tits stratification compares with the EKOR strata on the basic locu
s.\n
LOCATION:https://stable.researchseminars.org/talk/Postech-PMI-NT/12/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Kazuki Morimoto (Kobe University)
DTSTART:20260319T070000Z
DTEND:20260319T080000Z
DTSTAMP:20260404T095121Z
UID:Postech-PMI-NT/13
DESCRIPTION:Title: On an Ichino-Ikeda type formula for Whittaker periods and t
heta lifts\nby Kazuki Morimoto (Kobe University) as part of Postech-PM
I Number Theory Seminar\n\n\nAbstract\nAn Ichino-Ikeda type formula provid
es an explicit identity between special values of $L$-functions and period
s of automorphic forms. For example\, in joint works with Furusawa\, we pr
oved Ichino-Ikeda type formulas for Bessel periods for any irreducible cus
pidal tempered automorphic representations of $(\\mathrm{SO}(5)\, \\mathrm
{SO}(2))$\, using theta lifts for several dual pairs. In this talk\, I wil
l discuss about an extension of this approach to automorphic representatio
ns that are not necessarily tempered but generic. As a specific example of
this approach\, I will give a proof of an Ichino-Ikeda type formula of Wh
ittaker periods for any irreducible cuspidal automorphic representations o
f $\\mathrm{GSp}(4)$.\n
LOCATION:https://stable.researchseminars.org/talk/Postech-PMI-NT/13/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Andrei Seymour-Howell (Chonnam National University)
DTSTART:20260423T070000Z
DTEND:20260423T080000Z
DTSTAMP:20260404T095121Z
UID:Postech-PMI-NT/14
DESCRIPTION:by Andrei Seymour-Howell (Chonnam National University) as part
of Postech-PMI Number Theory Seminar\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/Postech-PMI-NT/14/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dongryul Kim (Stanford University)
DTSTART:20260409T070000Z
DTEND:20260409T080000Z
DTSTAMP:20260404T095121Z
UID:Postech-PMI-NT/15
DESCRIPTION:Title: Igusa stacks and the cohomology of Shimura varieties\nb
y Dongryul Kim (Stanford University) as part of Postech-PMI Number Theory
Seminar\n\n\nAbstract\nIgusa stacks are $p$-adic geometric objects\, recen
tly introduced by\nMingjia Zhang\, that roughly parametrize ways to $p$-ad
ically\nuniformize (global) Shimura varieties by local Shimura varieties.
In\njoint work with Patrick Daniels\, Pol van Hoften\, and Mingjia Zhang\,
we\nconstruct Igusa stacks for all abelian type Shimura data and apply\nt
hem to the study of $\\ell$-adic cohomology of Shimura varieties. I\nwill
discuss the geometric ingredients that go into the construction\nas well a
s how it naturally fits into Fargues--Scholze's framework of\ncategorical
local Langlands.\n
LOCATION:https://stable.researchseminars.org/talk/Postech-PMI-NT/15/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Haseo Ki (Yonsei University)
DTSTART:20260417T060000Z
DTEND:20260417T070000Z
DTSTAMP:20260404T095121Z
UID:Postech-PMI-NT/16
DESCRIPTION:Title: On the Bogomolny-Schmit Conjecture for Maass Forms\nby
Haseo Ki (Yonsei University) as part of Postech-PMI Number Theory Seminar\
n\n\nAbstract\nI will introduce the Bogomolny-Schmit Conjecture for Maass
Forms.\n
LOCATION:https://stable.researchseminars.org/talk/Postech-PMI-NT/16/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yunqing Tang (UC Berkeley)
DTSTART:20260514T000000Z
DTEND:20260514T010000Z
DTSTAMP:20260404T095121Z
UID:Postech-PMI-NT/17
DESCRIPTION:by Yunqing Tang (UC Berkeley) as part of Postech-PMI Number Th
eory Seminar\n\nAbstract: TBA\n
LOCATION:https://stable.researchseminars.org/talk/Postech-PMI-NT/17/
END:VEVENT
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