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過去の記録 ～06/11｜本日 06/12 | 今後の予定 06/13～
2026年06月10日(水)
代数学コロキウム
17:00-18:00 数理科学研究科棟(駒場) 117号室
Ana Caraiani 氏 (Imperial College London)
Towards an Eichler-Shimura decomposition for ordinary p-adic Siegel modular forms
Ana Caraiani 氏 (Imperial College London)
Towards an Eichler-Shimura decomposition for ordinary p-adic Siegel modular forms
[ 講演概要 ]
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.
東京名古屋代数セミナー
16:30-18:00 オンライン開催
Calvin Pfeifer 氏 (University of Cologne)
Generic modules arising from stability (English)
https://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
Calvin Pfeifer 氏 (University of Cologne)
Generic modules arising from stability (English)
[ 講演概要 ]
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
[ 参考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年06月09日(火)
作用素環セミナー
16:45-18:15 数理科学研究科棟(駒場) 126号室
星野泰佑 氏 (東大数理)
Rigidity for graph-wreath product II$_1$ factors
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
星野泰佑 氏 (東大数理)
Rigidity for graph-wreath product II$_1$ factors
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
トポロジー火曜セミナー
16:00-17:30 数理科学研究科棟(駒場) hybrid/056号室
対面参加、オンライン参加のいずれの場合もセミナーのホームページから参加登録を行って下さい。
田邊 真郷 氏 (理化学研究所数理創造研究センター)
Thom polynomials relative to maps prescribed near the boundary (JAPANESE)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
対面参加、オンライン参加のいずれの場合もセミナーのホームページから参加登録を行って下さい。
田邊 真郷 氏 (理化学研究所数理創造研究センター)
Thom polynomials relative to maps prescribed near the boundary (JAPANESE)
[ 講演概要 ]
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.
[ 参考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年06月08日(月)
複素解析幾何セミナー
10:30-12:00 数理科学研究科棟(駒場) 126号室
松本 佳彦 氏 (大阪大学)
CR-invariant energy of Legendrian knots in the Heisenberg group (Japanese)
https://forms.gle/8ERsVDLuKHwbVzm57
松本 佳彦 氏 (大阪大学)
CR-invariant energy of Legendrian knots in the Heisenberg group (Japanese)
[ 講演概要 ]
3次元Heisenberg群（接触構造を下部構造としてもつ）のLegendre結び目について、エネルギーの定義を与える。これは今井（1991年）による通常の結び目のエネルギーの類似である。通常の結び目のエネルギー（正確にいえば指数-2のもの）がメビウス変換で不変であるのに対し、Legendre結び目のエネルギーはPU(2,1)の作用で不変となる。ここでPU(2,1)は3次元Heisenberg群の一点コンパクト化のCR自己同型群である。この講演では、エネルギーをどう定義すればPU(2,1)不変性が得られるかということ、およびエネルギー最小元としてR-circlesが現れることについて、ていねいに説明したい。時間が許せば未解決の問題についても述べる。この講演は今井淳氏（千葉大学）との共同研究にもとづく。
[ 参考URL ]3次元Heisenberg群（接触構造を下部構造としてもつ）のLegendre結び目について、エネルギーの定義を与える。これは今井（1991年）による通常の結び目のエネルギーの類似である。通常の結び目のエネルギー（正確にいえば指数-2のもの）がメビウス変換で不変であるのに対し、Legendre結び目のエネルギーはPU(2,1)の作用で不変となる。ここでPU(2,1)は3次元Heisenberg群の一点コンパクト化のCR自己同型群である。この講演では、エネルギーをどう定義すればPU(2,1)不変性が得られるかということ、およびエネルギー最小元としてR-circlesが現れることについて、ていねいに説明したい。時間が許せば未解決の問題についても述べる。この講演は今井淳氏（千葉大学）との共同研究にもとづく。
https://forms.gle/8ERsVDLuKHwbVzm57
2026年06月05日(金)
代数幾何学セミナー
14:00-15:00 数理科学研究科棟(駒場) 大講義室（NISSAY Lecture Hall）号室
Young-Hoon Kiem 氏 (Korea Institute for Advanced Study)
Cohomology of moduli spaces of curves
Young-Hoon Kiem 氏 (Korea Institute for Advanced Study)
Cohomology of moduli spaces of curves
[ 講演概要 ]
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年06月04日(木)
応用解析セミナー
16:00-17:30 数理科学研究科棟(駒場) 002号室
白木 尚武 氏 (University of Zagreb)
Beckner's sharp inequalities revisited on binary cubes (Japanese)
白木 尚武 氏 (University of Zagreb)
Beckner's sharp inequalities revisited on binary cubes (Japanese)
[ 講演概要 ]
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年06月02日(火)
作用素環セミナー
16:45-18:15 数理科学研究科棟(駒場) 126号室
西中祐介 氏 (大阪公立大)
Costello-Gwilliam factorization algebras and vertex algebras
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
西中祐介 氏 (大阪公立大)
Costello-Gwilliam factorization algebras and vertex algebras
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
日仏数学拠点FJ-LMIセミナー
10:00-12:00 数理科学研究科棟(駒場) 号室
佐々田 槙子 氏 (東京大学大学院数理科学研究科)
Scaling Limits of Interacting Particle Systems: From Gaussian Fields to KPZ Universality
https://fj-lmi.cnrs.fr/fj-lmi-day-2026/
佐々田 槙子 氏 (東京大学大学院数理科学研究科)
Scaling Limits of Interacting Particle Systems: From Gaussian Fields to KPZ Universality
[ 講演概要 ]
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.
[ 参考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/
日仏数学拠点FJ-LMIセミナー
10:00-12:00 数理科学研究科棟(駒場) 号室
斎藤 毅 氏 (東京大学大学院数理科学研究科)
Some developments in cohomology theories in arithmetic (英語)
https://fj-lmi.cnrs.fr/fj-lmi-day-2026/
斎藤 毅 氏 (東京大学大学院数理科学研究科)
Some developments in cohomology theories in arithmetic (英語)
[ 講演概要 ]
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.
[ 参考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/
日仏数学拠点FJ-LMIセミナー
10:00-12:00 数理科学研究科棟(駒場) 号室
Luc PIRIO 氏 (CNRS FJ-LMI)
Lines, Curves, Surfaces, and Functional Equations
https://fj-lmi.cnrs.fr/fj-lmi-day-2026/
Luc PIRIO 氏 (CNRS FJ-LMI)
Lines, Curves, Surfaces, and Functional Equations
[ 講演概要 ]
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.
[ 参考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/
日仏数学拠点FJ-LMIセミナー
10:00-12:00 数理科学研究科棟(駒場) 号室
Valentin MASSICOT 氏 (CNRS FJ-LMI (IRL2025) & LMR (UMR 9008))
Double quotients for symmetry breaking
https://fj-lmi.cnrs.fr/fj-lmi-day-2026/
Valentin MASSICOT 氏 (CNRS FJ-LMI (IRL2025) & LMR (UMR 9008))
Double quotients for symmetry breaking
[ 講演概要 ]
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.
[ 参考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/
数値解析セミナー
16:30-18:00 数理科学研究科棟(駒場) 002号室
Mikhail Lavrentiev 氏 (Novosibirsk State University and Institute of Automation & Electrometry SB RAS)
Fast numerical solution to shallow water system at PC - application to tsunami simulation (English)
https://sites.google.com/g.ecc.u-tokyo.ac.jp/utnas-bulletin-board/
Mikhail Lavrentiev 氏 (Novosibirsk State University and Institute of Automation & Electrometry SB RAS)
Fast numerical solution to shallow water system at PC - application to tsunami simulation (English)
[ 講演概要 ]
To calculate the distribution of maximal tsunami wave heights along the shoreline immediately after the earthquake a number of algorithms have been developed. Due to the hardware acceleration (the use of FPGA - Field Programmable Gates Array - microchip) numerical solution to the shallow water system takes 1 minute with Personal Computer within 1000x600 km water area, grid step compared to 250 m.
It takes 25 min to compute wave propagation over the entire Pacific Ocean at 1 min grid. Using the advantages of FPGA architecture, values of wave parameters are calculated at 7 time layers at one computer clock. The propores technology could be applied for more problems in computational hydrodynamics.
[ 参考URL ]To calculate the distribution of maximal tsunami wave heights along the shoreline immediately after the earthquake a number of algorithms have been developed. Due to the hardware acceleration (the use of FPGA - Field Programmable Gates Array - microchip) numerical solution to the shallow water system takes 1 minute with Personal Computer within 1000x600 km water area, grid step compared to 250 m.
It takes 25 min to compute wave propagation over the entire Pacific Ocean at 1 min grid. Using the advantages of FPGA architecture, values of wave parameters are calculated at 7 time layers at one computer clock. The propores technology could be applied for more problems in computational hydrodynamics.
https://sites.google.com/g.ecc.u-tokyo.ac.jp/utnas-bulletin-board/
トポロジー火曜セミナー
16:00-17:30 数理科学研究科棟(駒場) hybrid/056号室
対面参加、オンライン参加のいずれの場合もセミナーのホームページから参加登録を行って下さい。
浅野 知紘 氏 (京都大学)
Knot types of Lagrangian intersections and epimorphisms between knot groups (JAPANESE)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
対面参加、オンライン参加のいずれの場合もセミナーのホームページから参加登録を行って下さい。
浅野 知紘 氏 (京都大学)
Knot types of Lagrangian intersections and epimorphisms between knot groups (JAPANESE)
[ 講演概要 ]
Lagrangian intersections in symplectic manifolds have been studied from various perspectives. In recent years, several works have also investigated the knot types of Lagrangian intersections.
In this talk, we discuss a problem posed by Okamoto. Starting from a knot in the 3-dimensional Euclidean space, we move its conormal bundle in the cotangent bundle by a compactly supported Hamiltonian isotopy. When its intersection with the zero-section is connected and clean, it gives rise to another knot. We ask how the knot type of this new knot is related to that of the original one.
I will explain a new constraint on this problem obtained by using microlocal sheaf theory, in terms of the fundamental groups of knot complements. This talk is based on joint work with Yukihiro Okamoto (Tokyo Metropolitan University).
[ 参考URL ]Lagrangian intersections in symplectic manifolds have been studied from various perspectives. In recent years, several works have also investigated the knot types of Lagrangian intersections.
In this talk, we discuss a problem posed by Okamoto. Starting from a knot in the 3-dimensional Euclidean space, we move its conormal bundle in the cotangent bundle by a compactly supported Hamiltonian isotopy. When its intersection with the zero-section is connected and clean, it gives rise to another knot. We ask how the knot type of this new knot is related to that of the original one.
I will explain a new constraint on this problem obtained by using microlocal sheaf theory, in terms of the fundamental groups of knot complements. This talk is based on joint work with Yukihiro Okamoto (Tokyo Metropolitan University).
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
日仏数学拠点FJ-LMIセミナー
10:00-12:00 数理科学研究科棟(駒場) 号室
小林俊行 氏 (東京大学大学院数理科学研究科)
Symmetry Breaking and Geometric Analysis
https://fj-lmi.cnrs.fr/fj-lmi-day-2026/
小林俊行 氏 (東京大学大学院数理科学研究科)
Symmetry Breaking and Geometric Analysis
[ 講演概要 ]
In this talk, I first give a brief overview of fundamental problems in the branching theory of infinite-dimensional representations, namely the study of restricted representations. I then discuss recent advances in this area and their applications to spectral analysis on locally symmetric spaces beyond the traditional Riemannian setting, with particular emphasis on joint work with French colleagues.
[ 参考URL ]In this talk, I first give a brief overview of fundamental problems in the branching theory of infinite-dimensional representations, namely the study of restricted representations. I then discuss recent advances in this area and their applications to spectral analysis on locally symmetric spaces beyond the traditional Riemannian setting, with particular emphasis on joint work with French colleagues.
https://fj-lmi.cnrs.fr/fj-lmi-day-2026/
2026年06月01日(月)
複素解析幾何セミナー
10:30-12:00 数理科学研究科棟(駒場) 126号室
小森 洋平 氏 (早稲田大学)
Classification of arithmetic twice-punctured torus groups (Japanese)
https://forms.gle/8ERsVDLuKHwbVzm57
小森 洋平 氏 (早稲田大学)
Classification of arithmetic twice-punctured torus groups (Japanese)
[ 講演概要 ]
A Fuchsian group is called arithmetic if it is commensurable with a Fuchsian group derived from a quaternion algebra. In this talk we will determine arithmetic twice-punctured torus groups; arithmetic once-punctured torus groups were already classified by Kisao Takeuchi. Our strategy is based on Takeuchi's approach to classify quadrilateral subgroups of the modular group. (“Subgroups of the modular group with signature (0 ; e1, e2, e3, e4)”（Saitama Math. Jour. Vol.14, 55—78, 1996).)
[ 参考URL ]A Fuchsian group is called arithmetic if it is commensurable with a Fuchsian group derived from a quaternion algebra. In this talk we will determine arithmetic twice-punctured torus groups; arithmetic once-punctured torus groups were already classified by Kisao Takeuchi. Our strategy is based on Takeuchi's approach to classify quadrilateral subgroups of the modular group. (“Subgroups of the modular group with signature (0 ; e1, e2, e3, e4)”（Saitama Math. Jour. Vol.14, 55—78, 1996).)
https://forms.gle/8ERsVDLuKHwbVzm57
2026年05月29日(金)
代数幾何学セミナー
13:15-14:45 数理科学研究科棟(駒場) 117号室
厚東 裕紀 氏 (Academia Sinica)
Towards a quantization of the Kirwan map via Fourier transform
厚東 裕紀 氏 (Academia Sinica)
Towards a quantization of the Kirwan map via Fourier transform
[ 講演概要 ]
Quantum cohomology ring is a deformation of the ordinary cohomology ring defined using counts of rational curves (genus zero Gromov-Witten invariants). In this talk, I will propose a Fourier transform for the quantum cohomology of smooth projective GIT quotients, viewed as a quantum analogue of the Kirwan map in ordinary cohomology. I will present several examples where this Fourier transform can be constructed and discuss some applications. This talk is based on ongoing work.
Quantum cohomology ring is a deformation of the ordinary cohomology ring defined using counts of rational curves (genus zero Gromov-Witten invariants). In this talk, I will propose a Fourier transform for the quantum cohomology of smooth projective GIT quotients, viewed as a quantum analogue of the Kirwan map in ordinary cohomology. I will present several examples where this Fourier transform can be constructed and discuss some applications. This talk is based on ongoing work.
2026年05月27日(水)
代数学コロキウム
17:00-18:00 数理科学研究科棟(駒場) 117号室
大西晴人 氏 (東京大学大学院数理科学研究科)
Geometric realization of the local Langlands and local Jacquet-Langlands correspondences for GL(4) in a partially ramified case
大西晴人 氏 (東京大学大学院数理科学研究科)
Geometric realization of the local Langlands and local Jacquet-Langlands correspondences for GL(4) in a partially ramified case
[ 講演概要 ]
The local Langlands correspondence and the local Jacquet-Langlands correspondence are realized using Lubin-Tate spaces. However, only limited cases of the correspondence between supercuspidal representations and L-parameters have been geometrically realized by algebraic varieties defined by explicit equations. There are several works in which such algebraic varieties are obtained as reductions of special affinoids in the Lubin-Tate space at infinite level. Even in the essentially tame case, where the correspondence is explicitly described by Bushnell–Henniart, such affinoids had previously been constructed only in the unramified and totally ramified cases. In this talk, I will explain a result constructing such affinoids in a partially ramified case, under certain special assumptions.
The local Langlands correspondence and the local Jacquet-Langlands correspondence are realized using Lubin-Tate spaces. However, only limited cases of the correspondence between supercuspidal representations and L-parameters have been geometrically realized by algebraic varieties defined by explicit equations. There are several works in which such algebraic varieties are obtained as reductions of special affinoids in the Lubin-Tate space at infinite level. Even in the essentially tame case, where the correspondence is explicitly described by Bushnell–Henniart, such affinoids had previously been constructed only in the unramified and totally ramified cases. In this talk, I will explain a result constructing such affinoids in a partially ramified case, under certain special assumptions.
東京名古屋代数セミナー
16:00-17:30 オンライン開催
水野 雄貴 氏 (Utrecht University)
Bondal–Orlov’s reconstruction theorem in noncommutative projective geometry (Japanese)
http://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
水野 雄貴 氏 (Utrecht University)
Bondal–Orlov’s reconstruction theorem in noncommutative projective geometry (Japanese)
[ 講演概要 ]
The (derived) category of coherent sheaves on a scheme encodes rich
information about the underlying geometry. P. Gabriel showed that for
noetherian schemes X and Y, if Coh X and Coh Y are equivalent as abelian
categories, then X and Y are isomorphic. Furthermore, A. Bondal and D.
Orlov proved that for smooth projective schemes X and Y with
(anti-)ample canonical bundles, if D^b(Coh X) and D^b(Coh Y) are
equivalent as triangulated categories, then X and Y are isomorphic. On
the other hand, J.-P. Serre showed that the category of coherent sheaves
on a projective scheme can be described as the quotient category of
finitely generated graded modules over the homogeneous coordinate ring
by the subcategory of torsion modules. Motivated by the results of
Gabriel and Serre, the quotient category of finitely generated graded
modules over a (not necessarily commutative) graded ring by the
subcategory of torsion modules is called a noncommutative projective scheme.
In this talk, I will present an analogue of Bondal–Orlov’s
reconstruction theorem for noncommutative projective geometry.
Furthermore, if time permits, I will discuss recent progress on the
study of the derived autoequivalence groups of noncommutative projective
schemes. Specifically, I will mention a structure result for the derived
autoequivalence groups of certain noncommutative projective planes.
ミーティング ID: 828 6882 8074
パスコード: 131261
[ 参考URL ]The (derived) category of coherent sheaves on a scheme encodes rich
information about the underlying geometry. P. Gabriel showed that for
noetherian schemes X and Y, if Coh X and Coh Y are equivalent as abelian
categories, then X and Y are isomorphic. Furthermore, A. Bondal and D.
Orlov proved that for smooth projective schemes X and Y with
(anti-)ample canonical bundles, if D^b(Coh X) and D^b(Coh Y) are
equivalent as triangulated categories, then X and Y are isomorphic. On
the other hand, J.-P. Serre showed that the category of coherent sheaves
on a projective scheme can be described as the quotient category of
finitely generated graded modules over the homogeneous coordinate ring
by the subcategory of torsion modules. Motivated by the results of
Gabriel and Serre, the quotient category of finitely generated graded
modules over a (not necessarily commutative) graded ring by the
subcategory of torsion modules is called a noncommutative projective scheme.
In this talk, I will present an analogue of Bondal–Orlov’s
reconstruction theorem for noncommutative projective geometry.
Furthermore, if time permits, I will discuss recent progress on the
study of the derived autoequivalence groups of noncommutative projective
schemes. Specifically, I will mention a structure result for the derived
autoequivalence groups of certain noncommutative projective planes.
ミーティング ID: 828 6882 8074
パスコード: 131261
http://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
2026年05月26日(火)
作用素環セミナー
16:45-18:15 数理科学研究科棟(駒場) 126号室
西原拓生 氏 (京大数理研)
Compact group actions and $G$-kernels on von Neumann algebras
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar-e.htm
西原拓生 氏 (京大数理研)
Compact group actions and $G$-kernels on von Neumann algebras
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar-e.htm
数値解析セミナー
16:30-18:00 数理科学研究科棟(駒場) 002号室
Qin(Tim) Sheng 氏 (Baylor University)
Advances in Splitting: Intercardinal Approaches to Nonlinear Hideo Kawarada Equations
(English)
https://sites.google.com/g.ecc.u-tokyo.ac.jp/utnas-bulletin-board/
Qin(Tim) Sheng 氏 (Baylor University)
Advances in Splitting: Intercardinal Approaches to Nonlinear Hideo Kawarada Equations
(English)
[ 講演概要 ]
This presentation addresses two main issues. First, we shall discuss recent advancements in both exponential and non-exponential splitting methods, with particular emphasis on their stability, accuracy and global error estimates. Second, we shall introduce a new splitting configuration for solving nonlinear Hideo Kawarada equations with mixed derivative terms. This approach leads to intercardinal splitting finite-difference schemes that provide efficient and accurate numerical approximations of the underlying solutions.
We shall further demonstrate that the resulting implicit methods are numerically stable, convergent, and efficient, while preserving key physical properties such as the positivity and monotonicity. The dynamic orders of accuracy of the proposed algorithms will be illustrated using generalized Milne devices. Simulation examples of the solution procedure will be presented and investigated, and several open problems will also be outlined.
[ 参考URL ]This presentation addresses two main issues. First, we shall discuss recent advancements in both exponential and non-exponential splitting methods, with particular emphasis on their stability, accuracy and global error estimates. Second, we shall introduce a new splitting configuration for solving nonlinear Hideo Kawarada equations with mixed derivative terms. This approach leads to intercardinal splitting finite-difference schemes that provide efficient and accurate numerical approximations of the underlying solutions.
We shall further demonstrate that the resulting implicit methods are numerically stable, convergent, and efficient, while preserving key physical properties such as the positivity and monotonicity. The dynamic orders of accuracy of the proposed algorithms will be illustrated using generalized Milne devices. Simulation examples of the solution procedure will be presented and investigated, and several open problems will also be outlined.
https://sites.google.com/g.ecc.u-tokyo.ac.jp/utnas-bulletin-board/
トポロジー火曜セミナー
16:00-17:30 数理科学研究科棟(駒場) hybrid/056号室
対面参加、オンライン参加のいずれの場合もセミナーのホームページから参加登録を行って下さい。
坂井 健人 氏 (東京大学大学院数理科学研究科)
On the large-scale geometry of k-multicurve graphs (JAPANESE)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
対面参加、オンライン参加のいずれの場合もセミナーのホームページから参加登録を行って下さい。
坂井 健人 氏 (東京大学大学院数理科学研究科)
On the large-scale geometry of k-multicurve graphs (JAPANESE)
[ 講演概要 ]
Graphs whose vertices are isotopy classes of simple closed curves, or multicurves, on surfaces have been widely studied, since they admit natural actions of mapping class groups. The curve graph and the pants graph are two fundamental examples. These graphs have found many applications in low-dimensional topology, including the study of Teichmüller spaces, Kleinian groups, and topology of 3-manifolds. In particular, the Gromov hyperbolicity of the curve graph, established by Masur and Minsky, played an important role in the proof of the Ending Lamination Theorem.
The k-multicurve graph, introduced by Erlandsson and Fanoni, is a graph whose vertices are multicurves with k components. It provides a natural interpolation between the curve graph and the pants graph. In this talk, we will present results on large-scale geometric properties of k-multicurve graphs, including hyperbolicity, relative hyperbolicity, and quasi-flat rank. If time permits, we will also discuss some connections with mapping class groups and Teichmüller spaces. This talk is based on joint work with Erika Kuno (Shibaura Institute of Technology) and Rin Kuramochi (The University of Tokyo).
[ 参考URL ]Graphs whose vertices are isotopy classes of simple closed curves, or multicurves, on surfaces have been widely studied, since they admit natural actions of mapping class groups. The curve graph and the pants graph are two fundamental examples. These graphs have found many applications in low-dimensional topology, including the study of Teichmüller spaces, Kleinian groups, and topology of 3-manifolds. In particular, the Gromov hyperbolicity of the curve graph, established by Masur and Minsky, played an important role in the proof of the Ending Lamination Theorem.
The k-multicurve graph, introduced by Erlandsson and Fanoni, is a graph whose vertices are multicurves with k components. It provides a natural interpolation between the curve graph and the pants graph. In this talk, we will present results on large-scale geometric properties of k-multicurve graphs, including hyperbolicity, relative hyperbolicity, and quasi-flat rank. If time permits, we will also discuss some connections with mapping class groups and Teichmüller spaces. This talk is based on joint work with Erika Kuno (Shibaura Institute of Technology) and Rin Kuramochi (The University of Tokyo).
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Lie群論・表現論セミナー
16:00-17:00 数理科学研究科棟(駒場) 128号室
ビクトール・ペレズ＝バルデス 氏 (東大数理)
On sporadic symmetry breaking operators from $S^3$ to $S^2$
ビクトール・ペレズ＝バルデス 氏 (東大数理)
On sporadic symmetry breaking operators from $S^3$ to $S^2$
[ 講演概要 ]
In this talk we construct and classify all differential symmetry breaking operators between certain principal series representations of the pair $(SO_0(4,1), SO_0(3,1))$.
In this case, we also prove a localness theorem, namely, all symmetry breaking operators between the principal series representations in concern are necessarily differential operators.
In addition, we show that all these symmetry breaking operators are sporadic, that is, they cannot be obtained by residue formulas of meromorphic families of symmetry breaking operators.
In this talk we construct and classify all differential symmetry breaking operators between certain principal series representations of the pair $(SO_0(4,1), SO_0(3,1))$.
In this case, we also prove a localness theorem, namely, all symmetry breaking operators between the principal series representations in concern are necessarily differential operators.
In addition, we show that all these symmetry breaking operators are sporadic, that is, they cannot be obtained by residue formulas of meromorphic families of symmetry breaking operators.
2026年05月25日(月)
複素解析幾何セミナー
10:30-12:00 数理科学研究科棟(駒場) 126号室
大橋 美佐 氏 (名古屋工業大学)
$S^{3} \times S^{3}$からみるHirzebruch曲面とその幾何構造 (Japanese)
https://forms.gle/8ERsVDLuKHwbVzm57
大橋 美佐 氏 (名古屋工業大学)
$S^{3} \times S^{3}$からみるHirzebruch曲面とその幾何構造 (Japanese)
[ 講演概要 ]
非負整数$m$に対してHirzebruch 曲面$W_{m}$は, 複素射影直線と複素射影平面の直積多様体の中の複素2次元のケーラー部分多様体である. $m$と$m′$が異なるとき, $W_{m}$と$W_{m′}$は正則同型でないことが知られている. 本講演では, $W_{m}$ 上の複素構造の差異を微分幾何学的な観点から捉えることを目的とする. $W_{m}$上のある2次元トーラス束が3次元球面の２個の直積$S^{3} \times S^{3}$と微分同型であることを用いて, 各Hirzebruch 曲面に対応する$S^{3} \times S^{3}$上の複素構造を大域的切断（テンソル場）として実現することを試みた．この微分同型の構成と性質, 及びその応用を紹介する.
[ 参考URL ]非負整数$m$に対してHirzebruch 曲面$W_{m}$は, 複素射影直線と複素射影平面の直積多様体の中の複素2次元のケーラー部分多様体である. $m$と$m′$が異なるとき, $W_{m}$と$W_{m′}$は正則同型でないことが知られている. 本講演では, $W_{m}$ 上の複素構造の差異を微分幾何学的な観点から捉えることを目的とする. $W_{m}$上のある2次元トーラス束が3次元球面の２個の直積$S^{3} \times S^{3}$と微分同型であることを用いて, 各Hirzebruch 曲面に対応する$S^{3} \times S^{3}$上の複素構造を大域的切断（テンソル場）として実現することを試みた．この微分同型の構成と性質, 及びその応用を紹介する.
https://forms.gle/8ERsVDLuKHwbVzm57
東京確率論セミナー
16:00-17:30 数理科学研究科棟(駒場) 126号室
15:15〜 ２階のコモンルームでTea timeを行います。ぜひこちらにもご参加ください。
岡嵜 郁也 氏 (東京科学大学)
非局所ディリクレ形式に関する調和写像の微分に付随する接束上のマルチンゲールについて
15:15〜 ２階のコモンルームでTea timeを行います。ぜひこちらにもご参加ください。
岡嵜 郁也 氏 (東京科学大学)
非局所ディリクレ形式に関する調和写像の微分に付随する接束上のマルチンゲールについて
[ 講演概要 ]
リーマン多様体が高次のユークリッド空間に埋め込まれているという仮定の下では, その多様体に値を取る非局所ディリクレ形式に関する調和写像を変分原理に基づいて定義できる. 例えば分数冪ラプラシアンに関するディリクレ形式を考えた場合は, Da Lio-Rivière (2011)で導入された分数冪ラプラシアンに関する調和写像に対応する. 本研究では値域の多様体の幾何と調和写像の関係を見ることを目的として, 調和写像にある程度の正則性を課し, その微分を確率過程を通して考察する. まず接束上の不連続なセミマルチンゲールに対する伊藤解析を, 第2基本形式などを用いてジャンプを定めることで定式化し, それを用いて接束上の不連続なマルチンゲールを導入する. また写像の定義域の空間として別のリーマン多様体と, その上のあるKillingベクトル場による変換で不変なディリクレ形式を考え, そのKillingベクトル場による調和写像の微分から定まるジャンプ過程が接束上のマルチンゲールとなることを紹介する.
リーマン多様体が高次のユークリッド空間に埋め込まれているという仮定の下では, その多様体に値を取る非局所ディリクレ形式に関する調和写像を変分原理に基づいて定義できる. 例えば分数冪ラプラシアンに関するディリクレ形式を考えた場合は, Da Lio-Rivière (2011)で導入された分数冪ラプラシアンに関する調和写像に対応する. 本研究では値域の多様体の幾何と調和写像の関係を見ることを目的として, 調和写像にある程度の正則性を課し, その微分を確率過程を通して考察する. まず接束上の不連続なセミマルチンゲールに対する伊藤解析を, 第2基本形式などを用いてジャンプを定めることで定式化し, それを用いて接束上の不連続なマルチンゲールを導入する. また写像の定義域の空間として別のリーマン多様体と, その上のあるKillingベクトル場による変換で不変なディリクレ形式を考え, そのKillingベクトル場による調和写像の微分から定まるジャンプ過程が接束上のマルチンゲールとなることを紹介する.
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