Text only print
Full screen print
Future seminars
Seminar information archive ～07/06｜Today's seminar 07/07 | Future seminars 07/08～
2025/07/08
Numerical Analysis Seminar
16:30-18:00 Room #126 (Graduate School of Math. Sci. Bldg.)
Masaki Imagawa (Kyoto Univsersity)
Convergence analysis of perturbed advection equations in a bounded domain (Japanese)
[ Reference URL ]
https://sites.google.com/g.ecc.u-tokyo.ac.jp/utnas-bulletin-board/
Masaki Imagawa (Kyoto Univsersity)
Convergence analysis of perturbed advection equations in a bounded domain (Japanese)
[ Reference URL ]
https://sites.google.com/g.ecc.u-tokyo.ac.jp/utnas-bulletin-board/
Tuesday Seminar of Analysis
16:00-17:30 Room #002 (Graduate School of Math. Sci. Bldg.)
Keisuke Takasao (Kyoto University)
Brakke's inequality and the existence of Brakke flow for volume preserving mean curvature flow (Japanese)
Keisuke Takasao (Kyoto University)
Brakke's inequality and the existence of Brakke flow for volume preserving mean curvature flow (Japanese)
[ Abstract ]
We consider the existence of the weak solutions to the volume preserving mean curvature flow. The Brakke flow defined using Brakke's inequality is well known as one of the weak solutions to the mean curvature flow. On the other hand, the volume preserving mean curvature flow has been studied via $L^2$-flow solution, BV solution, and flat flow, but the corresponding Brakke flow had not been considered so far. In this talk, we define the suitable Brakke flow for the volume preserving flow and show its global existence. This talk is based on joint works with Andrea Chiesa (University of Vienna).
We consider the existence of the weak solutions to the volume preserving mean curvature flow. The Brakke flow defined using Brakke's inequality is well known as one of the weak solutions to the mean curvature flow. On the other hand, the volume preserving mean curvature flow has been studied via $L^2$-flow solution, BV solution, and flat flow, but the corresponding Brakke flow had not been considered so far. In this talk, we define the suitable Brakke flow for the volume preserving flow and show its global existence. This talk is based on joint works with Andrea Chiesa (University of Vienna).
Lie Groups and Representation Theory
16:00-17:00 Room #128 (Graduate School of Math. Sci. Bldg.)
Koichi Arashi (Tokyo Gakugei University)
On integral representations of reproducing kernels on quasi-symmetric Siegel domains
Koichi Arashi (Tokyo Gakugei University)
On integral representations of reproducing kernels on quasi-symmetric Siegel domains
[ Abstract ]
L.\ Schwartz established the foundational theory of reproducing kernels in the 1960s.
Around the same time, S.\ G.\ Gindikin obtained an explicit integral representation of the Bergman kernel for the Siegel domain of the second kind $\mathcal{S}(\Omega,Q)\subset U_{\mathbb C}\times V$.
This formula suggests that the set of irreducible unitary representations of the generalized Heisenberg group $G^{V}=U\rtimes V$ realized on this domain is embedded in the unitary dual of the group.
Such a notion of multiplicity-freeness property has since been reconsidered from a complex-geometric standpoint, motivated by Huckleberry–Wurzbacher's study of ``coisotropic actions'' and by T.\ Kobayashi's introduction of ``visible actions'', and its understanding continues to deepen.
In this talk, we focus on a quasi-symmetric Siegel domain, and for a real subspace $W\subset V$, study the representations of the subgroup $G^{W}=U\rtimes W$.
We show that the multiplicity-freeness property can be characterized both by geometric features of the group action and by the multiplicity-free irreducible decomposition of the unitary representation on the Bergman space.
L.\ Schwartz established the foundational theory of reproducing kernels in the 1960s.
Around the same time, S.\ G.\ Gindikin obtained an explicit integral representation of the Bergman kernel for the Siegel domain of the second kind $\mathcal{S}(\Omega,Q)\subset U_{\mathbb C}\times V$.
This formula suggests that the set of irreducible unitary representations of the generalized Heisenberg group $G^{V}=U\rtimes V$ realized on this domain is embedded in the unitary dual of the group.
Such a notion of multiplicity-freeness property has since been reconsidered from a complex-geometric standpoint, motivated by Huckleberry–Wurzbacher's study of ``coisotropic actions'' and by T.\ Kobayashi's introduction of ``visible actions'', and its understanding continues to deepen.
In this talk, we focus on a quasi-symmetric Siegel domain, and for a real subspace $W\subset V$, study the representations of the subgroup $G^{W}=U\rtimes W$.
We show that the multiplicity-freeness property can be characterized both by geometric features of the group action and by the multiplicity-free irreducible decomposition of the unitary representation on the Bergman space.
Tuesday Seminar on Topology
17:00-18:30 Room #hybrid/056 (Graduate School of Math. Sci. Bldg.)
Pre-registration required. See our seminar webpage.
Hiroki Ishikura (The University of Tokyo)
Stallings-Swan’s Theorem for Borel graphs (JAPANESE)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Pre-registration required. See our seminar webpage.
Hiroki Ishikura (The University of Tokyo)
Stallings-Swan’s Theorem for Borel graphs (JAPANESE)
[ Abstract ]
A Borel graph is a simplicial graph on a standard Borel space X such that the edge set is a Borel subset of X^2. Such objects have been studied in the context of countable Borel equivalence relations, and recently there are many attempts to apply the ideas of geometric group theory to them. Stallings-Swan's theorem states that groups of cohomological dimension 1 are free groups. We will talk about an analog of this theorem for Borel graphs: A Borel graph on X with uniformly bounded degrees of cohomological dimension 1 is Lipschitz equivalent to a Borel acyclic graph on X. This is proved by establishing a criterion for certain decomposition of Borel graphs, which is inspired by Dunwoody's work on accessibility of groups.
[ Reference URL ]A Borel graph is a simplicial graph on a standard Borel space X such that the edge set is a Borel subset of X^2. Such objects have been studied in the context of countable Borel equivalence relations, and recently there are many attempts to apply the ideas of geometric group theory to them. Stallings-Swan's theorem states that groups of cohomological dimension 1 are free groups. We will talk about an analog of this theorem for Borel graphs: A Borel graph on X with uniformly bounded degrees of cohomological dimension 1 is Lipschitz equivalent to a Borel acyclic graph on X. This is proved by establishing a criterion for certain decomposition of Borel graphs, which is inspired by Dunwoody's work on accessibility of groups.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
thesis presentations
13:15-14:30 Room #128 (Graduate School of Math. Sci. Bldg.)
SATO Genki (東京大学大学院数理科学研究科)
Presentation of finite Reedy categories as localizations
of finite direct categories
(有限直圏の局所化としての有限Reedy圏の表示)
SATO Genki (東京大学大学院数理科学研究科)
Presentation of finite Reedy categories as localizations
of finite direct categories
(有限直圏の局所化としての有限Reedy圏の表示)
Tokyo-Nagoya Algebra Seminar
10:30-12:00 Online
Nao Mochizuki (Nagoya University)
On the Auslander—Reiten theory for extended hearts of proper connective DG-algebras (Japanese)
http://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
Nao Mochizuki (Nagoya University)
On the Auslander—Reiten theory for extended hearts of proper connective DG-algebras (Japanese)
[ Abstract ]
本講演では, proper connective DG代数のd-extended heartにおけるAuslander-Reiten理論 を紹介する.
講演の主な対象となるd-extended heartsは, コホモロジーが次数0から−d+1の間に集中するようなDG加群からなる導来圏の部分圏である. 特に, 有限次元代数の場合，1-extended heart は, 通常の有限生成加群圏に一致する.
本講演では，この有限生成加群圏におけるAuslander-Reiten理論が, d-extended hearts を用いることで proper connective DG代数の文脈にまで一般化されることを紹介する. また, DG-quiverから構成されるDG代数に対するAR-quiverの具体的な計算例も併せて紹介する.
Zoom ID 870 3048 1997 Password 392212
[ Reference URL ]本講演では, proper connective DG代数のd-extended heartにおけるAuslander-Reiten理論 を紹介する.
講演の主な対象となるd-extended heartsは, コホモロジーが次数0から−d+1の間に集中するようなDG加群からなる導来圏の部分圏である. 特に, 有限次元代数の場合，1-extended heart は, 通常の有限生成加群圏に一致する.
本講演では，この有限生成加群圏におけるAuslander-Reiten理論が, d-extended hearts を用いることで proper connective DG代数の文脈にまで一般化されることを紹介する. また, DG-quiverから構成されるDG代数に対するAR-quiverの具体的な計算例も併せて紹介する.
Zoom ID 870 3048 1997 Password 392212
http://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
2025/07/10
Geometric Analysis Seminar
14:00-15:00 Room #056 (Graduate School of Math. Sci. Bldg.)
Jeff Viaclovsky (University of California, Irvine)
TBA (英語)
Jeff Viaclovsky (University of California, Irvine)
TBA (英語)
[ Abstract ]
TBA
TBA
2025/07/14
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.
Hirotatsu Nagoji (Kyoto University)
Singularity of solutions to singular SPDEs
We are having teatime from 15:15 in the common room on the second floor. Please join us.
Hirotatsu Nagoji (Kyoto University)
Singularity of solutions to singular SPDEs
[ Abstract ]
We give a sufficient condition for the marginal distribution of the solution to singular SPDEs on the $d$-dimensional torus to be singular with respect to the law of the Gaussian measure induced by the corresponding linear equation. As applications we obtain the singularity of the $\phi^4_3$-quantum field measure with respect to the Gaussian free field measure and the border of parameters for the fractional $\phi^4$-measure to be singular with respect to the base Gaussian measure. Our approach is applicable to quite a large class of singular SPDEs. This talk is based on a joint work with S. Kusuoka (Kyoto University) and M. Hairer (EPFL).
We give a sufficient condition for the marginal distribution of the solution to singular SPDEs on the $d$-dimensional torus to be singular with respect to the law of the Gaussian measure induced by the corresponding linear equation. As applications we obtain the singularity of the $\phi^4_3$-quantum field measure with respect to the Gaussian free field measure and the border of parameters for the fractional $\phi^4$-measure to be singular with respect to the base Gaussian measure. Our approach is applicable to quite a large class of singular SPDEs. This talk is based on a joint work with S. Kusuoka (Kyoto University) and M. Hairer (EPFL).
Infinite Analysis Seminar Tokyo
15:30 (仮)-16:30 (仮) Room #056 (Graduate School of Math. Sci. Bldg.)
Danilo Lewański (University of Trieste)
A spin on Gromov-Witten / Hurwitz correspondence and integrability
(English)
Danilo Lewański (University of Trieste)
A spin on Gromov-Witten / Hurwitz correspondence and integrability
(English)
[ Abstract ]
Hurwitz numbers enumerate branched coverings of Riemann surfaces and provide a rich sandbox of examples for enumerative geometry and neighbouring areas. Surprisingly, there is a formula that connects them to the intersection theory of the moduli spaces of stable curves: the ELSV formula. Furthermore, these numbers enjoy an integrability of type 2D-Toda as they can be expressed as vacuum expectations in the Fock space, result that has been later employed in the GW/Hurwitz correspondence.
A spin-off from the research on the mirror symmetry on Calabi-Yau 3-folds led to the spin generation of Hurwitz numbers via topological recursion. Over time this result has been generalised in different directions, including the Hurwitz count of Riemann surfaces with a spin structure, which are conjecturally determining Gromov-Witten invariants of surfaces with smooth canonical divisor. This led once more to the link with integrability, this time of type BKP.
Hurwitz numbers enumerate branched coverings of Riemann surfaces and provide a rich sandbox of examples for enumerative geometry and neighbouring areas. Surprisingly, there is a formula that connects them to the intersection theory of the moduli spaces of stable curves: the ELSV formula. Furthermore, these numbers enjoy an integrability of type 2D-Toda as they can be expressed as vacuum expectations in the Fock space, result that has been later employed in the GW/Hurwitz correspondence.
A spin-off from the research on the mirror symmetry on Calabi-Yau 3-folds led to the spin generation of Hurwitz numbers via topological recursion. Over time this result has been generalised in different directions, including the Hurwitz count of Riemann surfaces with a spin structure, which are conjecturally determining Gromov-Witten invariants of surfaces with smooth canonical divisor. This led once more to the link with integrability, this time of type BKP.
2025/07/15
Tuesday Seminar on Topology
17:00-18:30 Room #056 (Graduate School of Math. Sci. Bldg.)
Pre-registration required. See our seminar webpage.
Anastasiia Tsvietkova (Rutgers University)
Polynomially many genus g surfaces in a hyperbolic 3-manifold (ENGLISH)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Pre-registration required. See our seminar webpage.
Anastasiia Tsvietkova (Rutgers University)
Polynomially many genus g surfaces in a hyperbolic 3-manifold (ENGLISH)
[ Abstract ]
For a low-dimensional manifold, one often tries to understand its intrinsic topology through its submanifolds, in particular of co-dimension 1. For example,
it was noticed before that presence of embedded essential surfaces in a 3-manifold can give information about that manifold. However to construct, classify or count such surfaces is a non-trivial task. We will discuss a universal upper bound for the number of non-isotopic genus g surfaces embedded in a hyperbolic 3-manifold, polynomial in hyperbolic volume. The surfaces are all closed essential surfaces, oriented and connected. This is joint work with Marc Lackenby.
[ Reference URL ]For a low-dimensional manifold, one often tries to understand its intrinsic topology through its submanifolds, in particular of co-dimension 1. For example,
it was noticed before that presence of embedded essential surfaces in a 3-manifold can give information about that manifold. However to construct, classify or count such surfaces is a non-trivial task. We will discuss a universal upper bound for the number of non-isotopic genus g surfaces embedded in a hyperbolic 3-manifold, polynomial in hyperbolic volume. The surfaces are all closed essential surfaces, oriented and connected. This is joint work with Marc Lackenby.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Tokyo-Nagoya Algebra Seminar
15:30-17:00 Online
Shunsuke Hirota (Kyoto University)
super category Oにおけるsemibrick (Japanese)
[ Reference URL ]
https://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
Shunsuke Hirota (Kyoto University)
super category Oにおけるsemibrick (Japanese)
[ Reference URL ]
https://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
2025/07/22
Operator Algebra Seminars
16:45-18:15 Room #117 (Graduate School of Math. Sci. Bldg.)
Giovanni Ferrer (Ohio State University)
Higher quantum symmetries
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Giovanni Ferrer (Ohio State University)
Higher quantum symmetries
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Tuesday Seminar on Topology
17:00-18:30 Room #hybrid/056 (Graduate School of Math. Sci. Bldg.)
Pre-registration required. See our seminar webpage.
Alexis Marchand (Kyoto University)
Sharp spectral gaps for scl from negative curvature (ENGLISH)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Pre-registration required. See our seminar webpage.
Alexis Marchand (Kyoto University)
Sharp spectral gaps for scl from negative curvature (ENGLISH)
[ Abstract ]
Stable commutator length is a measure of homological complexity of group elements, with connections to many topics in geometric topology, including quasimorphisms, bounded cohomology, and simplicial volume. The goal of this talk is to shed light on some of its relations with negative curvature. We will present a new geometric proof of a theorem of Heuer on sharp lower bounds for scl in right-angled Artin groups. Our proof relates letter-quasimorphisms (which are analogues of real-valued quasimorphisms with image in free groups) to negatively curved angle structures for surfaces estimating scl.
[ Reference URL ]Stable commutator length is a measure of homological complexity of group elements, with connections to many topics in geometric topology, including quasimorphisms, bounded cohomology, and simplicial volume. The goal of this talk is to shed light on some of its relations with negative curvature. We will present a new geometric proof of a theorem of Heuer on sharp lower bounds for scl in right-angled Artin groups. Our proof relates letter-quasimorphisms (which are analogues of real-valued quasimorphisms with image in free groups) to negatively curved angle structures for surfaces estimating scl.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
thesis presentations
11:00-12:15 Room #118 (Graduate School of Math. Sci. Bldg.)
KATAYAMA Sho (東京大学大学院数理科学研究科)
On positive solutions to inhomogeneous elliptic problems
on unbounded domains
(非有界傾域上の非斉次楕円型問題の正値解について)
KATAYAMA Sho (東京大学大学院数理科学研究科)
On positive solutions to inhomogeneous elliptic problems
on unbounded domains
(非有界傾域上の非斉次楕円型問題の正値解について)
2025/07/29
Numerical Analysis Seminar
16:30-18:00 Room #123 (Graduate School of Math. Sci. Bldg.)
Takashi Suzuki (Osaka University)
An analytic proof of the Hodge decomposition on bounded domains in Euclidean space and its applications (Japanese)
Takashi Suzuki (Osaka University)
An analytic proof of the Hodge decomposition on bounded domains in Euclidean space and its applications (Japanese)
2025/08/22
thesis presentations
16:00-17:15 Room #128 (Graduate School of Math. Sci. Bldg.)
HOSHINO Mao (東京大学大学院数理科学研究科)
A tensor categorical aspect of quantum group actions
(量子群作用のテンソル圏的様相)
HOSHINO Mao (東京大学大学院数理科学研究科)
A tensor categorical aspect of quantum group actions
(量子群作用のテンソル圏的様相)
2025/09/09
Operator Algebra Seminars
16:45-18:15 Room #126 (Graduate School of Math. Sci. Bldg.)
Kang Li (FAU Erlangen-Nürnberg)
Dimension theories from groupoids to classifiable $C^*$-algebras, and back again
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/seminar/operalge/future.html
Kang Li (FAU Erlangen-Nürnberg)
Dimension theories from groupoids to classifiable $C^*$-algebras, and back again
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/seminar/operalge/future.html
