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Seminar information archive
Seminar information archive ～06/26｜Today's seminar 06/27 | Future seminars 06/28～
2026/06/26
Colloquium
15:30-16:30 Room #NISSAY Lecture Hall (Graduate School of Math. Sci. Bldg.)
Bez Neal (Graduate School of Mathematical Sciences, The University of Tokyo)
The Kakeya conjecture and the Brascamp-Lieb inequality (日本語)
Bez Neal (Graduate School of Mathematical Sciences, The University of Tokyo)
The Kakeya conjecture and the Brascamp-Lieb inequality (日本語)
[ Abstract ]
Despite being ostensibly a problem in geometric measure theory,
the Kakeya conjecture has huge significance in modern Fourier analysis.
After discussing this connection,
I will explain the relevance of the Brascamp-Lieb inequality in this context
and introduce some recent progress in the theory of this inequality.
Despite being ostensibly a problem in geometric measure theory,
the Kakeya conjecture has huge significance in modern Fourier analysis.
After discussing this connection,
I will explain the relevance of the Brascamp-Lieb inequality in this context
and introduce some recent progress in the theory of this inequality.
Geometric Analysis Seminar
13:30-14;30 Room #002 (Graduate School of Math. Sci. Bldg.)
Federica Dragoni (Cardiff University)
Convexity: from the Euclidean space to Riemannian and sub-Riemannian manifolds (英語)
https://sites.google.com/g.ecc.u-tokyo.ac.jp/geometricanalysisseminar/
Federica Dragoni (Cardiff University)
Convexity: from the Euclidean space to Riemannian and sub-Riemannian manifolds (英語)
[ Abstract ]
In this talk I will give an overview on different notions of convexity introduced in the last decades to generalise the standard (Euclidean) convexity to different geometries such as Riemannian manifolds, Carnot groups and the geometry of vector fields. Later I will show some more recent developments and how this new geometrical approach can connect most of the previous notions.
[ Reference URL ]In this talk I will give an overview on different notions of convexity introduced in the last decades to generalise the standard (Euclidean) convexity to different geometries such as Riemannian manifolds, Carnot groups and the geometry of vector fields. Later I will show some more recent developments and how this new geometrical approach can connect most of the previous notions.
https://sites.google.com/g.ecc.u-tokyo.ac.jp/geometricanalysisseminar/
Seminar on Probability and Statistics
13:30-14:30 Room #122 (Graduate School of Math. Sci. Bldg.)
Prof. Hsin-Hsiung 'Bill’ Huang (School of Data, Mathematical, and Statistical Sciences, University of Central Florida)
Scalable Bayesian Conformal Inference for High-Dimensional Spatiotemporal Zero-Inflated Count Data (English)
https://u-tokyo-ac-jp.zoom.us/meeting/register/UmviZSskR766wD4QoUvP2g
Prof. Hsin-Hsiung 'Bill’ Huang (School of Data, Mathematical, and Statistical Sciences, University of Central Florida)
Scalable Bayesian Conformal Inference for High-Dimensional Spatiotemporal Zero-Inflated Count Data (English)
[ Abstract ]
I will present a Bayesian framework for spatiotemporal count data with excess zeros, overdispersion, and ultrahigh-dimensional covariates. The model combines zero-inflated negative binomial regression, TPBN shrinkage priors for sparse fixed effects, graph-Laplacian or SPDE-type spatial random effects, smooth global time effects, and unit-specific Ornstein--Uhlenbeck SDE random effects. Pólya--Gamma augmentation yields a conditionally Gaussian structure, supporting both blocked Gibbs sampling and scalable structured variational inference. I will also discuss split conformal calibration for discrete predictive sets and an auxiliary LAQ/QMLE perspective for the OU component. Simulation studies and a measles surveillance analysis illustrate calibrated prediction and recovery of latent spatiotemporal structure.
[ Reference URL ]I will present a Bayesian framework for spatiotemporal count data with excess zeros, overdispersion, and ultrahigh-dimensional covariates. The model combines zero-inflated negative binomial regression, TPBN shrinkage priors for sparse fixed effects, graph-Laplacian or SPDE-type spatial random effects, smooth global time effects, and unit-specific Ornstein--Uhlenbeck SDE random effects. Pólya--Gamma augmentation yields a conditionally Gaussian structure, supporting both blocked Gibbs sampling and scalable structured variational inference. I will also discuss split conformal calibration for discrete predictive sets and an auxiliary LAQ/QMLE perspective for the OU component. Simulation studies and a measles surveillance analysis illustrate calibrated prediction and recovery of latent spatiotemporal structure.
https://u-tokyo-ac-jp.zoom.us/meeting/register/UmviZSskR766wD4QoUvP2g
2026/06/25
Applied Analysis
16:00-17:30 Room # 002 (Graduate School of Math. Sci. Bldg.)
Xiao Dongyuan (Tohoku University)
Complete classification of traveling wave solutions to monotone dynamical systems (Japanese)
Xiao Dongyuan (Tohoku University)
Complete classification of traveling wave solutions to monotone dynamical systems (Japanese)
[ Abstract ]
To study the propagation phenomena of solutions to the reaction-diffusion equation the asymptotic behavior of traveling wave solutions plays a crucial role. When the nonlinear reaction term satisfies the monostable condition, it is known that there exists a minimal traveling wave speed, and that traveling wave solutions exist for any speed c larger than or equal to the minimal speed. It has been shown, through simple phase plane analysis, that these traveling waves can be classified into three cases based on their decay rates.
It Is expected that a similar classification should hold for more general order-preserving systems, such as nonlocal diffusion equations, Lotka–Volterra systems, and reaction–diffusion equations with time delay. However, a complete classification remains unavailable because direct phase plane analysis is no longer applicable in these settings. In this talk, I will introduce a method based on comparison argument and sliding method to classify traveling waves. This research is based on joint work with Maolin Zhou (Nankai University) and Chang-hong Wu (National Yang Ming Chiao Tung University).
To study the propagation phenomena of solutions to the reaction-diffusion equation the asymptotic behavior of traveling wave solutions plays a crucial role. When the nonlinear reaction term satisfies the monostable condition, it is known that there exists a minimal traveling wave speed, and that traveling wave solutions exist for any speed c larger than or equal to the minimal speed. It has been shown, through simple phase plane analysis, that these traveling waves can be classified into three cases based on their decay rates.
It Is expected that a similar classification should hold for more general order-preserving systems, such as nonlocal diffusion equations, Lotka–Volterra systems, and reaction–diffusion equations with time delay. However, a complete classification remains unavailable because direct phase plane analysis is no longer applicable in these settings. In this talk, I will introduce a method based on comparison argument and sliding method to classify traveling waves. This research is based on joint work with Maolin Zhou (Nankai University) and Chang-hong Wu (National Yang Ming Chiao Tung University).
2026/06/23
Operator Algebra Seminars
16:45-18:15 Room #126 (Graduate School of Math. Sci. Bldg.)
Ravi Mistry (the University of Tokyo)
Knots, Invariants, QFT, and Beyond
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Ravi Mistry (the University of Tokyo)
Knots, Invariants, QFT, and Beyond
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Tuesday Seminar on Topology
16:00-17:30 Room #hybrid/056 (Graduate School of Math. Sci. Bldg.)
Pre-registration required. See our seminar webpage.
Andrei Pajitnov (Université de Nantes)
Morse-Novikov theory for links (ENGLISH)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Pre-registration required. See our seminar webpage.
Andrei Pajitnov (Université de Nantes)
Morse-Novikov theory for links (ENGLISH)
[ Abstract ]
Let M be a compact manifold with a non-empty boundary N, and x an element of the first cohomology group of M. We assume that the restriction of x to N can be represented by a fibration over a circle. The Morse-Novikov number MN(M,x) is the minimal possible number of critical points of a Morse map f of M to a circle, such that [f]=x, and the restriction of f to N is a fibration over the circle. In this talk we present our results about the Morse-Novikov numbers for the exteriors of links in 3-sphere. This is joint work with L. Chen and H. Endo.
[ Reference URL ]Let M be a compact manifold with a non-empty boundary N, and x an element of the first cohomology group of M. We assume that the restriction of x to N can be represented by a fibration over a circle. The Morse-Novikov number MN(M,x) is the minimal possible number of critical points of a Morse map f of M to a circle, such that [f]=x, and the restriction of f to N is a fibration over the circle. In this talk we present our results about the Morse-Novikov numbers for the exteriors of links in 3-sphere. This is joint work with L. Chen and H. Endo.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
2026/06/22
Seminar on Geometric Complex Analysis
10:30-12:00 Room #126 (Graduate School of Math. Sci. Bldg.)
Online only. No in-person attendance.
Naoto Yotsutani (Shizuoka Univ./IMAG, Univ. Montpellier)
Secondary polytopes of spherical varieties (Japanese)
https://forms.gle/8ERsVDLuKHwbVzm57
Online only. No in-person attendance.
Naoto Yotsutani (Shizuoka Univ./IMAG, Univ. Montpellier)
Secondary polytopes of spherical varieties (Japanese)
[ Abstract ]
This talk is based on ongoing joint work with Thibaut Delcroix and King Leung Lee. Our main objective is to investigate the Chow stability of spherical varieties.
A celebrated theorem of Gelfand, Kapranov, Sturmfels, and Zelevinsky (1992) states that the Chow polytopes of projective toric varieties coincide with their secondary polytopes. In the spherical setting, one can construct an analogous polytope, which may be viewed as a natural generalization of the secondary polytope of a toric variety. In this talk, I will explain the construction of this polytope and its relation to Chow stability. Particular emphasis will be placed on how the classical GKZ argument in the toric setting can be adapted to the broader context of spherical varieties.
[ Reference URL ]This talk is based on ongoing joint work with Thibaut Delcroix and King Leung Lee. Our main objective is to investigate the Chow stability of spherical varieties.
A celebrated theorem of Gelfand, Kapranov, Sturmfels, and Zelevinsky (1992) states that the Chow polytopes of projective toric varieties coincide with their secondary polytopes. In the spherical setting, one can construct an analogous polytope, which may be viewed as a natural generalization of the secondary polytope of a toric variety. In this talk, I will explain the construction of this polytope and its relation to Chow stability. Particular emphasis will be placed on how the classical GKZ argument in the toric setting can be adapted to the broader context of spherical varieties.
https://forms.gle/8ERsVDLuKHwbVzm57
Tokyo Probability Seminar
16:00-17:30 Room #126 (Graduate School of Math. Sci. Bldg.)
We are having teatime from 15:15 in the common room on the second floor. Please join us.
Manasa Nagatsu (Kyoto University)
Large $N$ expansion for smooth multi-trace spectral statistics of
classical matrix ensembles, central limit theorems and matrix integrals.
We are having teatime from 15:15 in the common room on the second floor. Please join us.
Manasa Nagatsu (Kyoto University)
Large $N$ expansion for smooth multi-trace spectral statistics of
classical matrix ensembles, central limit theorems and matrix integrals.
[ Abstract ]
We consider expectations of the form $E [tr h_1(X_1^N)... tr h_r(X_r^N)]$,
where $X_i^N$ are self-adjoint polynomials in various independent
classical random matrices and $h_i$ are smooth test function and obtain a
large $N$ expansion of these quantities, building on the framework of
polynomial approximation and Bernstein-type inequalities recently
developed by Chen, Garza-Vargas, Tropp, and van Handel.
As applications of the above, we prove the higher-order asymptotic
vanishing of cumulants for smooth linear statistics, establish a Central
Limit Theorem, and demonstrate the existence of formal asymptotic
expansions for the free energy and observables of matrix integrals with
smooth potentials.
In addition to presenting these results, we will briefly review the role
of linear statistics in random matrix theory and discuss the motivation
behind the large $N$ expansion framework introduced in the context of
strong convergence.
This talk is based on joint work with Benoit Collins.
We consider expectations of the form $E [tr h_1(X_1^N)... tr h_r(X_r^N)]$,
where $X_i^N$ are self-adjoint polynomials in various independent
classical random matrices and $h_i$ are smooth test function and obtain a
large $N$ expansion of these quantities, building on the framework of
polynomial approximation and Bernstein-type inequalities recently
developed by Chen, Garza-Vargas, Tropp, and van Handel.
As applications of the above, we prove the higher-order asymptotic
vanishing of cumulants for smooth linear statistics, establish a Central
Limit Theorem, and demonstrate the existence of formal asymptotic
expansions for the free energy and observables of matrix integrals with
smooth potentials.
In addition to presenting these results, we will briefly review the role
of linear statistics in random matrix theory and discuss the motivation
behind the large $N$ expansion framework introduced in the context of
strong convergence.
This talk is based on joint work with Benoit Collins.
2026/06/18
Logic
15:30-17:30 Room #122 (Graduate School of Math. Sci. Bldg.)
Paul Larson (Miami University)
Discontinuous homomorphisms without Hamel bases
Paul Larson (Miami University)
Discontinuous homomorphisms without Hamel bases
[ Abstract ]
A Hamel basis for the real line is a basis for the line over the scalar field of rational numbers. The Axiom of Choice implies that Hamel bases exist. It is a classical fact that every measurable homomorphism from the additive group on the real line to itself is continuous, and therefore is given by multiplication by some real number. However, permutations of Hamel bases naturally give rise to discontinuous homomorphisms. In this talk we will show that this implication cannot be reversed, by forcing to produce a model of ZF in which there exists a discontinuous homomorphism but there is no Hamel basis. This is joint work with Saharon Shelah.
A Hamel basis for the real line is a basis for the line over the scalar field of rational numbers. The Axiom of Choice implies that Hamel bases exist. It is a classical fact that every measurable homomorphism from the additive group on the real line to itself is continuous, and therefore is given by multiplication by some real number. However, permutations of Hamel bases naturally give rise to discontinuous homomorphisms. In this talk we will show that this implication cannot be reversed, by forcing to produce a model of ZF in which there exists a discontinuous homomorphism but there is no Hamel basis. This is joint work with Saharon Shelah.
2026/06/16
Operator Algebra Seminars
16:45-18:15 Room #126 (Graduate School of Math. Sci. Bldg.)
Hiroki Ishikura (RIMS, Kyoto Univ.)
Borel planar complexes and soficity
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Hiroki Ishikura (RIMS, Kyoto Univ.)
Borel planar complexes and soficity
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Tuesday Seminar on Topology
16:00-17:30 Room #hybrid/128 (Graduate School of Math. Sci. Bldg.)
Pre-registration required. See our seminar webpage.
Yuto Moriwaki (RIKEN iTHEMS)
Conformally flat factorization homology (JAPANESE)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Pre-registration required. See our seminar webpage.
Yuto Moriwaki (RIKEN iTHEMS)
Conformally flat factorization homology (JAPANESE)
[ Abstract ]
This talk presents conformally flat factorization homology, introduced as a conformal Riemannian analogue of Lurie's factorization homology. Ordinary factorization homology takes a d-disk algebra as input and produces invariants of d-dimensional manifolds that are independent of the choice of metric. In contrast, conformally flat factorization homology takes as input a conformally flat d-disk algebra, which is an algebra over the operad formed by conformal open embeddings of disks, and constructs, via its left Kan extension, metric-dependent invariants of conformally flat Riemannian manifolds.
This theory provides a framework connecting representations of local conformal transformations with Riemannian geometric invariants, and describes the local structure of d-dimensional conformal field theory. The talk will also discuss concrete examples constructed using Bergman spaces and Grunsky operators in dimension two, and using unitary representations of SO+(d,1) in dimensions three and higher.
This talk is based on arXiv:2602.08729 and arXiv:2603.06491.
[ Reference URL ]This talk presents conformally flat factorization homology, introduced as a conformal Riemannian analogue of Lurie's factorization homology. Ordinary factorization homology takes a d-disk algebra as input and produces invariants of d-dimensional manifolds that are independent of the choice of metric. In contrast, conformally flat factorization homology takes as input a conformally flat d-disk algebra, which is an algebra over the operad formed by conformal open embeddings of disks, and constructs, via its left Kan extension, metric-dependent invariants of conformally flat Riemannian manifolds.
This theory provides a framework connecting representations of local conformal transformations with Riemannian geometric invariants, and describes the local structure of d-dimensional conformal field theory. The talk will also discuss concrete examples constructed using Bergman spaces and Grunsky operators in dimension two, and using unitary representations of SO+(d,1) in dimensions three and higher.
This talk is based on arXiv:2602.08729 and arXiv:2603.06491.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
2026/06/15
Tokyo Probability Seminar
16:00-17:30 Room #126 (Graduate School of Math. Sci. Bldg.)
We are having teatime from 15:15 in the common room on the second floor. Please join us.
Tomoyuki Ichiba (University of California Santa Barbara)
Feynman formula for discrete-time quantum walk and its applications
We are having teatime from 15:15 in the common room on the second floor. Please join us.
Tomoyuki Ichiba (University of California Santa Barbara)
Feynman formula for discrete-time quantum walk and its applications
[ Abstract ]
We explicitly connect (discrete-time) quantum walks on Z with a four-state Markov additive process via a Feynman-type formula. Using this representation, we derive a relation between the spectral decomposition of the Markov additive process and the limiting density of the homogeneous quantum walk. In addition, we consider a space-time rescaling of quantum walks, which leads to a system of quantum transport PDEs of Dirac type in continuous time and space with phase interaction and potential terms. Our probabilistic representation for this type of PDE offers its stochastic extension as well as an efficient Monte Carlo computational technique. This is joint work with Jean-Pierre Fouque and Ka Lok Lam.
We explicitly connect (discrete-time) quantum walks on Z with a four-state Markov additive process via a Feynman-type formula. Using this representation, we derive a relation between the spectral decomposition of the Markov additive process and the limiting density of the homogeneous quantum walk. In addition, we consider a space-time rescaling of quantum walks, which leads to a system of quantum transport PDEs of Dirac type in continuous time and space with phase interaction and potential terms. Our probabilistic representation for this type of PDE offers its stochastic extension as well as an efficient Monte Carlo computational technique. This is joint work with Jean-Pierre Fouque and Ka Lok Lam.
FJ-LMI Seminar
10:30-12:00 Room #002 (Graduate School of Math. Sci. Bldg.)
Eric Leclerc, . Fabrizio Cleri, Yuki Miura, Stephane Poulain (LIMMS & IIS of The University of Tokyo)
- Introduction to a quantum inspired model of the mitochondria dysfunction in liver disease;
- From Boltzmann to Lindblad: quantum systems out of equilibrium;
- A hybrid liver model of mechanistic ODE systems and machine learning;
- Presentation of research background in bioinformatics and genomics, and introduction to new research projects for in silico liver organ physiology modeling using AI and informatics tools. (英語)
Eric Leclerc, . Fabrizio Cleri, Yuki Miura, Stephane Poulain (LIMMS & IIS of The University of Tokyo)
- Introduction to a quantum inspired model of the mitochondria dysfunction in liver disease;
- From Boltzmann to Lindblad: quantum systems out of equilibrium;
- A hybrid liver model of mechanistic ODE systems and machine learning;
- Presentation of research background in bioinformatics and genomics, and introduction to new research projects for in silico liver organ physiology modeling using AI and informatics tools. (英語)
[ Abstract ]
These 4 short presentations will focus on possible interactions between two laboratories.
These 4 short presentations will focus on possible interactions between two laboratories.
2026/06/10
Number Theory Seminar
17:00-18:00 Room #117 (Graduate School of Math. Sci. Bldg.)
Ana Caraiani (Imperial College London)
Towards an Eichler-Shimura decomposition for ordinary p-adic Siegel modular forms
Ana Caraiani (Imperial College London)
Towards an Eichler-Shimura decomposition for ordinary p-adic Siegel modular forms
[ Abstract ]
There are two different ways to construct families of ordinary p-adic Siegel modular forms. One is by p-adically interpolating classes in Betti cohomology, first introduced by Hida and then given a more representation-theoretic interpretation by Emerton. The other is by p-adically interpolating classes in coherent cohomology, once again pioneered by Hida and generalised in recent years by Boxer and Pilloni. I will explain these two constructions and then discuss joint work in progress with James Newton and Juan Esteban Rodríguez Camargo that aims to compare them.
There are two different ways to construct families of ordinary p-adic Siegel modular forms. One is by p-adically interpolating classes in Betti cohomology, first introduced by Hida and then given a more representation-theoretic interpretation by Emerton. The other is by p-adically interpolating classes in coherent cohomology, once again pioneered by Hida and generalised in recent years by Boxer and Pilloni. I will explain these two constructions and then discuss joint work in progress with James Newton and Juan Esteban Rodríguez Camargo that aims to compare them.
Tokyo-Nagoya Algebra Seminar
16:30-18:00 Online
Calvin Pfeifer (University of Cologne)
Generic modules arising from stability (English)
https://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
Calvin Pfeifer (University of Cologne)
Generic modules arising from stability (English)
[ Abstract ]
This talk is a report on joint work in progress with Lidia Angeleri-Hügel and Rosanna Laking. Our aim is to extend parts of the theory of large modules over tame hereditary algebras to arbitrary tame algebras.
Let A be a tame finite dimensional algebra over an algebraically closed field, and θ an additive functional on the Grothendieck group of A. Baumann, Kamnitzer and Tingley associate to θ a wide interval in the lattice of torsion classes of the category of finite dimensional A-modules, whose corresponding wide subcategory consists of the θ-semistable A-modules in the sense of King. Angeleri-Hügel, Laking and Sentieri use cosilting theory to assign to such a wide interval a closed rigid subset of the Ziegler spectrum of the unbounded derived category of all A-modules. On the other hand, Plamondon associates to θ a generically $τ^-$-regular irreducible component of the scheme of A-modules. In this talk, we will explain how the closed rigid subset of the Ziegler spectrum is determined by generic modules constructed from the generically $τ^-$-regular irreducible component.
Zoom ID 839 3959 5057
password 518784
[ Reference URL ]This talk is a report on joint work in progress with Lidia Angeleri-Hügel and Rosanna Laking. Our aim is to extend parts of the theory of large modules over tame hereditary algebras to arbitrary tame algebras.
Let A be a tame finite dimensional algebra over an algebraically closed field, and θ an additive functional on the Grothendieck group of A. Baumann, Kamnitzer and Tingley associate to θ a wide interval in the lattice of torsion classes of the category of finite dimensional A-modules, whose corresponding wide subcategory consists of the θ-semistable A-modules in the sense of King. Angeleri-Hügel, Laking and Sentieri use cosilting theory to assign to such a wide interval a closed rigid subset of the Ziegler spectrum of the unbounded derived category of all A-modules. On the other hand, Plamondon associates to θ a generically $τ^-$-regular irreducible component of the scheme of A-modules. In this talk, we will explain how the closed rigid subset of the Ziegler spectrum is determined by generic modules constructed from the generically $τ^-$-regular irreducible component.
Zoom ID 839 3959 5057
password 518784
https://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
2026/06/09
Operator Algebra Seminars
16:45-18:15 Room #126 (Graduate School of Math. Sci. Bldg.)
Taisuke Hoshino (Univ. Tokyo)
Rigidity for graph-wreath product II$_1$ factors
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Taisuke Hoshino (Univ. Tokyo)
Rigidity for graph-wreath product II$_1$ factors
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Tuesday Seminar on Topology
16:00-17:30 Room #hybrid/056 (Graduate School of Math. Sci. Bldg.)
Pre-registration required. See our seminar webpage.
Masato Tanabe (RIKEN iTHEMS)
Thom polynomials relative to maps prescribed near the boundary (JAPANESE)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Pre-registration required. See our seminar webpage.
Masato Tanabe (RIKEN iTHEMS)
Thom polynomials relative to maps prescribed near the boundary (JAPANESE)
[ Abstract ]
Thom polynomials are universal cohomological obstructions to the appearance of singularities of given types in differentiable maps. Introduced by R. Thom in the 1950s, they have been extensively studied ever since. In one important line of applications, various invariants of immersions have been expressed in terms of singularities of their extensions (a.k.a. singular Seifert surfaces). However, these formulas are obtained in different forms and remain somewhat scattered.
In this talk, as the first step to unify them, I would like to introduce the notion of Thom polynomials relative to prescribed maps around the boundary. As a main result, we show a structure theorem of Thom polynomials relative to framed immersions. In fact, most of the earlier formulas are summarized as the vanishing of "correction terms" appearing in the structure theorem. Our key tools are Steenrod's obstruction theory and Kervaire's relative characteristic classes, and the K-invariance of singularity types plays an important role.
[ Reference URL ]Thom polynomials are universal cohomological obstructions to the appearance of singularities of given types in differentiable maps. Introduced by R. Thom in the 1950s, they have been extensively studied ever since. In one important line of applications, various invariants of immersions have been expressed in terms of singularities of their extensions (a.k.a. singular Seifert surfaces). However, these formulas are obtained in different forms and remain somewhat scattered.
In this talk, as the first step to unify them, I would like to introduce the notion of Thom polynomials relative to prescribed maps around the boundary. As a main result, we show a structure theorem of Thom polynomials relative to framed immersions. In fact, most of the earlier formulas are summarized as the vanishing of "correction terms" appearing in the structure theorem. Our key tools are Steenrod's obstruction theory and Kervaire's relative characteristic classes, and the K-invariance of singularity types plays an important role.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
2026/06/08
Seminar on Geometric Complex Analysis
10:30-12:00 Room #126 (Graduate School of Math. Sci. Bldg.)
Yoshihiko Matsumoto (The Univ. of Osaka)
CR-invariant energy of Legendrian knots in the Heisenberg group (Japanese)
https://forms.gle/8ERsVDLuKHwbVzm57
Yoshihiko Matsumoto (The Univ. of Osaka)
CR-invariant energy of Legendrian knots in the Heisenberg group (Japanese)
[ Abstract ]
We introduce an energy functional for Legendrian knots in the 3-dimensional Heisenberg group, which carries a natural contact structure. This is an analogue of the energy for ordinary knots in Euclidean 3-space due to O'Hara (1991). Whereas O'Hara's energy (more precisely, the one of exponent -2) is invariant under Möbius transformations, our energy for Legendrian knots is invariant under the action of PU(2,1), the group of CR automorphisms of the one-point compactification of the Heisenberg group. I would like to explain carefully how the energy should be defined so as to achieve the PU(2,1)-invariance, and how R-circles, a distinguished class of Legendrian (un)knots, arise as energy minimizers. Time permitting, I will also discuss some open problems. This talk is based on joint work with Jun O'Hara (Chiba University).
[ Reference URL ]We introduce an energy functional for Legendrian knots in the 3-dimensional Heisenberg group, which carries a natural contact structure. This is an analogue of the energy for ordinary knots in Euclidean 3-space due to O'Hara (1991). Whereas O'Hara's energy (more precisely, the one of exponent -2) is invariant under Möbius transformations, our energy for Legendrian knots is invariant under the action of PU(2,1), the group of CR automorphisms of the one-point compactification of the Heisenberg group. I would like to explain carefully how the energy should be defined so as to achieve the PU(2,1)-invariance, and how R-circles, a distinguished class of Legendrian (un)knots, arise as energy minimizers. Time permitting, I will also discuss some open problems. This talk is based on joint work with Jun O'Hara (Chiba University).
https://forms.gle/8ERsVDLuKHwbVzm57
2026/06/05
Algebraic Geometry Seminar
14:00-15:00 Room #大講義室（NISSAY Lecture Hall） (Graduate School of Math. Sci. Bldg.)
Young-Hoon Kiem (Korea Institute for Advanced Study)
Cohomology of moduli spaces of curves
Young-Hoon Kiem (Korea Institute for Advanced Study)
Cohomology of moduli spaces of curves
[ Abstract ]
Moduli spaces of stable pointed curves have been much studied but still we know surprisingly little about their cohomology. In this talk, I will discuss some recent progresses based on techniques from combinatorics and probability theory as well as the algebraic geometry of wall crossings in the stack of maps.
Moduli spaces of stable pointed curves have been much studied but still we know surprisingly little about their cohomology. In this talk, I will discuss some recent progresses based on techniques from combinatorics and probability theory as well as the algebraic geometry of wall crossings in the stack of maps.
2026/06/04
Applied Analysis
16:00-17:30 Room # 002 (Graduate School of Math. Sci. Bldg.)
Shobu Shiraki (University of Zagreb)
Beckner's sharp inequalities revisited on binary cubes (Japanese)
Shobu Shiraki (University of Zagreb)
Beckner's sharp inequalities revisited on binary cubes (Japanese)
[ Abstract ]
The Hausdorff–Young inequality and Young’s convolution inequality are fundamental tools in harmonic analysis. The landmark paper “Inequalities in Fourier Analysis” by William Beckner (Ann. of Math., 1975) established the exact values of the sharp constants appearing in these inequalities. Recently, these inequalities have received renewed attention in the setting of binary cubes, driven by applications in additive combinatorics through works by Kane–Tao, de Dios Pont–Greenfeld–Ivanisvili–Madrid, and others. In this discrete setting, the sharp constant is known to be 1 and is no longer the central issue. Instead, the focus shifts to the range of exponents for which the Hausdorff–Young inequality and Young’s convolution inequality hold — a range that is enlarged compared to the classical case. In this talk, we aim to fully characterize this range. This is joint work with Tonći Crmarić (University of Split) and Vjekoslav Kovač (University of Zagreb).
The Hausdorff–Young inequality and Young’s convolution inequality are fundamental tools in harmonic analysis. The landmark paper “Inequalities in Fourier Analysis” by William Beckner (Ann. of Math., 1975) established the exact values of the sharp constants appearing in these inequalities. Recently, these inequalities have received renewed attention in the setting of binary cubes, driven by applications in additive combinatorics through works by Kane–Tao, de Dios Pont–Greenfeld–Ivanisvili–Madrid, and others. In this discrete setting, the sharp constant is known to be 1 and is no longer the central issue. Instead, the focus shifts to the range of exponents for which the Hausdorff–Young inequality and Young’s convolution inequality hold — a range that is enlarged compared to the classical case. In this talk, we aim to fully characterize this range. This is joint work with Tonći Crmarić (University of Split) and Vjekoslav Kovač (University of Zagreb).
2026/06/02
Operator Algebra Seminars
16:45-18:15 Room #126 (Graduate School of Math. Sci. Bldg.)
Yusuke Nishinaka (Osaka Metropolitan Univ.)
Costello-Gwilliam factorization algebras and vertex algebras
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Yusuke Nishinaka (Osaka Metropolitan Univ.)
Costello-Gwilliam factorization algebras and vertex algebras
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
FJ-LMI Seminar
10:00-12:00 Room # (Graduate School of Math. Sci. Bldg.)
Makiko SASADA (The University of Tokyo)
Scaling Limits of Interacting Particle Systems: From Gaussian Fields to KPZ Universality
https://fj-lmi.cnrs.fr/fj-lmi-day-2026/
Makiko SASADA (The University of Tokyo)
Scaling Limits of Interacting Particle Systems: From Gaussian Fields to KPZ Universality
[ Abstract ]
This talk explores the scaling limits of interacting particle systems with multiple conserved quantities. Starting from weakly asymmetric dynamics on a lattice, we characterize the evolution of fluctuation fields in the diffusive limit. We show how the interplay between different conserved modes leads to a transition from linear Gaussian fields to the KPZ (Kardar-Parisi-Zhang) universality class. Using the framework of Nonlinear Fluctuating Hydrodynamics, we discuss how the second-order nonlinearities in the macroscopic currents determine whether each mode exhibits diffusive or anomalous scaling. This talk is based on joint work with Hugo Da Cunha.
[ Reference URL ]This talk explores the scaling limits of interacting particle systems with multiple conserved quantities. Starting from weakly asymmetric dynamics on a lattice, we characterize the evolution of fluctuation fields in the diffusive limit. We show how the interplay between different conserved modes leads to a transition from linear Gaussian fields to the KPZ (Kardar-Parisi-Zhang) universality class. Using the framework of Nonlinear Fluctuating Hydrodynamics, we discuss how the second-order nonlinearities in the macroscopic currents determine whether each mode exhibits diffusive or anomalous scaling. This talk is based on joint work with Hugo Da Cunha.
https://fj-lmi.cnrs.fr/fj-lmi-day-2026/
FJ-LMI Seminar
10:00-12:00 Room # (Graduate School of Math. Sci. Bldg.)
Takeshi SAITO (The University of Tokyo)
Some developments in cohomology theories in arithmetic (英語)
https://fj-lmi.cnrs.fr/fj-lmi-day-2026/
Takeshi SAITO (The University of Tokyo)
Some developments in cohomology theories in arithmetic (英語)
[ Abstract ]
The introduction of cohomology theories into arithmetic geometry has its roots in the Weil conjectures and began with Grothendieck’s definition of étale cohomology in the 1960s. We will discuss several more recent developments, particularly those arising from collaborations between French and Japanese mathematicians, including motives with modulus, $p$-adic Simpson correspondences, and analogies with microlocal analysis.
[ Reference URL ]The introduction of cohomology theories into arithmetic geometry has its roots in the Weil conjectures and began with Grothendieck’s definition of étale cohomology in the 1960s. We will discuss several more recent developments, particularly those arising from collaborations between French and Japanese mathematicians, including motives with modulus, $p$-adic Simpson correspondences, and analogies with microlocal analysis.
https://fj-lmi.cnrs.fr/fj-lmi-day-2026/
FJ-LMI Seminar
10:00-12:00 Room # (Graduate School of Math. Sci. Bldg.)
Luc PIRIO (CNRS FJ-LMI)
Lines, Curves, Surfaces, and Functional Equations
https://fj-lmi.cnrs.fr/fj-lmi-day-2026/
Luc PIRIO (CNRS FJ-LMI)
Lines, Curves, Surfaces, and Functional Equations
[ Abstract ]
This short talk will offer an informal and visual introduction to families of curves on surfaces, and explain how these geometric objects naturally lead to an interesting class of functional equations.
[ Reference URL ]This short talk will offer an informal and visual introduction to families of curves on surfaces, and explain how these geometric objects naturally lead to an interesting class of functional equations.
https://fj-lmi.cnrs.fr/fj-lmi-day-2026/
FJ-LMI Seminar
10:00-12:00 Room # (Graduate School of Math. Sci. Bldg.)
Valentin MASSICOT (CNRS FJ-LMI (IRL2025) & LMR (UMR 9008))
Double quotients for symmetry breaking
https://fj-lmi.cnrs.fr/fj-lmi-day-2026/
Valentin MASSICOT (CNRS FJ-LMI (IRL2025) & LMR (UMR 9008))
Double quotients for symmetry breaking
[ Abstract ]
The orbit structure in flag varieties encodes branching laws for real reductive groups. In this talk, we describe a family of double quotients which arise naturally in the context of symmetry breaking for the general linear group.
These spaces generalize certain classical quotients, a fundamental example being the one associated with Gaussian elimination and the Bruhat decomposition. In this setting, double cosets are described using natural invariants inspired by the ranks of submatrices in the classical case.
[ Reference URL ]The orbit structure in flag varieties encodes branching laws for real reductive groups. In this talk, we describe a family of double quotients which arise naturally in the context of symmetry breaking for the general linear group.
These spaces generalize certain classical quotients, a fundamental example being the one associated with Gaussian elimination and the Bruhat decomposition. In this setting, double cosets are described using natural invariants inspired by the ranks of submatrices in the classical case.
https://fj-lmi.cnrs.fr/fj-lmi-day-2026/
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