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過去の記録
過去の記録 ～10/06｜本日 10/07 | 今後の予定 10/08～
2026年07月08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
Vova Sosnilo 氏 (理化学研究所 数理創造研究センター)
Descent for algebraic K-theory of algebraic stacks
https://vova-sosnilo.com/
Vova Sosnilo 氏 (理化学研究所 数理創造研究センター)
Descent for algebraic K-theory of algebraic stacks
[ 講演概要 ]
Algebraic K-theory satisfies descent with respect to Nisnevich covers, which allows one to deduce global computations for schemes to the affine case. For algebraic stacks this is insufficient, since algebraic stacks with nontrivial stabilizers do not admit Nisnevich covers by affine schemes. However, a theorem of Deshmukh shows that any algebraic stack with separated diagonal admits a Nisnevich surjection from an affine scheme. The Atiyah—Segal completion theorem measures precisely the failure of algebraic K-theory to satisfy descent with respect to Nisnevich surjections. We show that it holds for ANS algebraic stacks of finite type over a field of characteristic 0 using trace methods and equivariant resolution of singularities. Time permitting, we discuss an ongoing work attempting to extend this result in characteristic p.
[ 参考URL ]Algebraic K-theory satisfies descent with respect to Nisnevich covers, which allows one to deduce global computations for schemes to the affine case. For algebraic stacks this is insufficient, since algebraic stacks with nontrivial stabilizers do not admit Nisnevich covers by affine schemes. However, a theorem of Deshmukh shows that any algebraic stack with separated diagonal admits a Nisnevich surjection from an affine scheme. The Atiyah—Segal completion theorem measures precisely the failure of algebraic K-theory to satisfy descent with respect to Nisnevich surjections. We show that it holds for ANS algebraic stacks of finite type over a field of characteristic 0 using trace methods and equivariant resolution of singularities. Time permitting, we discuss an ongoing work attempting to extend this result in characteristic p.
https://vova-sosnilo.com/
東京名古屋代数セミナー
13:00-14:30 オンライン開催
髙谷 悠太 氏 (東京大学)
Characteristic-free approaches around Yu's construction (Japanese)
https://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
髙谷 悠太 氏 (東京大学)
Characteristic-free approaches around Yu's construction (Japanese)
[ 講演概要 ]
Yu's construction is one of the most wide-ranging constructions of supercuspidal representations. Recently, Fintzen, Kaletha, and Spice introduced a quadratic twist of this construction to build stable L-packets, which also appears in the geometric realization via positive-depth Deligne-Lusztig induction. In this talk, I will present a direct approach to twisted Yu's construction and explain how to remove technical conditions on small primes in the theory of Yu's construction and positive-depth Deligne-Lusztig induction.
Zoom ID 882 6509 3568 Password 616173
[ 参考URL ]Yu's construction is one of the most wide-ranging constructions of supercuspidal representations. Recently, Fintzen, Kaletha, and Spice introduced a quadratic twist of this construction to build stable L-packets, which also appears in the geometric realization via positive-depth Deligne-Lusztig induction. In this talk, I will present a direct approach to twisted Yu's construction and explain how to remove technical conditions on small primes in the theory of Yu's construction and positive-depth Deligne-Lusztig induction.
Zoom ID 882 6509 3568 Password 616173
https://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
2026年07月07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
橋本七海 氏 (慶応大)
Equivalence of categories of KK-theory or E-theory for $C^*$-algebras over topological spaces by reflection functors
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
橋本七海 氏 (慶応大)
Equivalence of categories of KK-theory or E-theory for $C^*$-algebras over topological spaces by reflection functors
[ 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
16:00-17:00 オンライン開催
セミナーのホームページから参加登録を行って下さい。
矢ヶ崎 達彦 氏 ( 京都工芸繊維大学)
Topological properties of groups of volume-preserving diffeomorphisms and groups of uniform homeomorphisms (JAPANESE)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
セミナーのホームページから参加登録を行って下さい。
矢ヶ崎 達彦 氏 ( 京都工芸繊維大学)
Topological properties of groups of volume-preserving diffeomorphisms and groups of uniform homeomorphisms (JAPANESE)
[ 講演概要 ]
This talk is a continuation of survey on topological properties of groups of homeomorphisms/diffeomorphisms on noncompact manifolds. As a subject related to ends of noncompact manifolds, we discuss volume transfer towards ends, which leads to the existence of continuous sections under the compact-open topology for the actions of diffeomorphism groups on the spaces of volume forms on noncompact manifolds (a noncompact version of Moser's theorem) and for the end charge homomorphisms introduced by Alpern and Prasad. We also give a brief survey on the local and end deformation properties in groups of uniform homeomorphisms on noncompact metric manifolds with the sup-metric.
[ 参考URL ]This talk is a continuation of survey on topological properties of groups of homeomorphisms/diffeomorphisms on noncompact manifolds. As a subject related to ends of noncompact manifolds, we discuss volume transfer towards ends, which leads to the existence of continuous sections under the compact-open topology for the actions of diffeomorphism groups on the spaces of volume forms on noncompact manifolds (a noncompact version of Moser's theorem) and for the end charge homomorphisms introduced by Alpern and Prasad. We also give a brief survey on the local and end deformation properties in groups of uniform homeomorphisms on noncompact metric manifolds with the sup-metric.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
2026年07月06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
Xiaojun Wu 氏 (筑波大学)
Generalised Ueda Obstruction Classes and Non-Semipositive Line Bundles (English)
https://forms.gle/8ERsVDLuKHwbVzm57
Xiaojun Wu 氏 (筑波大学)
Generalised Ueda Obstruction Classes and Non-Semipositive Line Bundles (English)
[ 講演概要 ]
Serre’s classical example provides a fundamental instance of a nef but non-semipositive line bundle and motivated the analytic definition of nefness introduced by Demailly–Peternell–Schneider. Building on subsequent developments by Koike, the classical Ueda obstruction classes provide a natural criterion for non-semipositivity. In this talk, we introduce a natural generalisation of the Ueda obstruction classes that is always well defined and for which the Chern curvature naturally determines representatives. As an application, we obtain an elementary and systematic method for constructing nef but non-semipositive line bundles.
[ 参考URL ]Serre’s classical example provides a fundamental instance of a nef but non-semipositive line bundle and motivated the analytic definition of nefness introduced by Demailly–Peternell–Schneider. Building on subsequent developments by Koike, the classical Ueda obstruction classes provide a natural criterion for non-semipositivity. In this talk, we introduce a natural generalisation of the Ueda obstruction classes that is always well defined and for which the Chern curvature naturally determines representatives. As an application, we obtain an elementary and systematic method for constructing nef but non-semipositive line bundles.
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
15:20〜 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。
舟木直久 氏 (北京雁栖湖応用数学研究院)
Interface motion from non-gradient Glauber-Kawasaki dynamics
15:20〜 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。
舟木直久 氏 (北京雁栖湖応用数学研究院)
Interface motion from non-gradient Glauber-Kawasaki dynamics
[ 講演概要 ]
Motivated by the problem of dynamic phase transitions, we study the derivation of interface motion from non-gradient Glauber-Kawasaki dynamics. In the balanced case, the limiting interface evolves according to the anisotropic curvature flow, while in the unbalanced case it is governed by a geometric Hamilton-Jacobi equation. We establish this result as a quantitative hydrodynamic limit and, by applying the method of quantitative homogenization, obtain convergence rates. We also investigate fluctuations of the interface and derive a linear stochastic partial differential equation. This talk is partially based on several joint works with Chenlin Gu (Tsinghua U), Han Wang (Tsinghua U), Shuhan Zhou (Peking U), Hyunjoon Park (Meiji U), Claudio Landim (IMPA), Sunder Sethuraman (U Arizona).
Motivated by the problem of dynamic phase transitions, we study the derivation of interface motion from non-gradient Glauber-Kawasaki dynamics. In the balanced case, the limiting interface evolves according to the anisotropic curvature flow, while in the unbalanced case it is governed by a geometric Hamilton-Jacobi equation. We establish this result as a quantitative hydrodynamic limit and, by applying the method of quantitative homogenization, obtain convergence rates. We also investigate fluctuations of the interface and derive a linear stochastic partial differential equation. This talk is partially based on several joint works with Chenlin Gu (Tsinghua U), Han Wang (Tsinghua U), Shuhan Zhou (Peking U), Hyunjoon Park (Meiji U), Claudio Landim (IMPA), Sunder Sethuraman (U Arizona).
2026年07月03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
吉川 翔 氏 (東京科学大学)
Hodge–Tate splitting and Akizuki–Nakano vanishing
吉川 翔 氏 (東京科学大学)
Hodge–Tate splitting and Akizuki–Nakano vanishing
[ 講演概要 ]
Akizuki–Nakano vanishing theorem は、Kodaira vanishing theorem を微分形式係数のコホモロジーへ拡張する基本的な消滅定理であり、複素代数幾何においてコホモロジーの制御や変形理論に重要な役割を果たす。一方、正標数ではこの定理は一般には成立せず、どのような幾何学的条件の下で同様の消滅定理が成り立つかは、自然かつ重要な問題である。
この方向の出発点として、Deligne–Illusie は、滑らかな固有多様体がW_2-lift をもち、かつその次元が標数より小さい場合に、de Rham complex の分解を用いて Akizuki–Nakano vanishing を証明した。近年、Petrov は quasi-F-split 多様体に対して、次元に関する制限なしに Akizuki–Nakano vanishing が従うことを証明した。
本講演では、これらの結果を統一的に捉える枠組みとして Hodge–Tate splitting という条件を考察し、この条件から Akizuki–Nakano vanishing が導かれることを説明する。また、この結果の混標数における類似についても紹介したい。
本講演は石塚彾氏との共同研究に基づく。
Akizuki–Nakano vanishing theorem は、Kodaira vanishing theorem を微分形式係数のコホモロジーへ拡張する基本的な消滅定理であり、複素代数幾何においてコホモロジーの制御や変形理論に重要な役割を果たす。一方、正標数ではこの定理は一般には成立せず、どのような幾何学的条件の下で同様の消滅定理が成り立つかは、自然かつ重要な問題である。
この方向の出発点として、Deligne–Illusie は、滑らかな固有多様体がW_2-lift をもち、かつその次元が標数より小さい場合に、de Rham complex の分解を用いて Akizuki–Nakano vanishing を証明した。近年、Petrov は quasi-F-split 多様体に対して、次元に関する制限なしに Akizuki–Nakano vanishing が従うことを証明した。
本講演では、これらの結果を統一的に捉える枠組みとして Hodge–Tate splitting という条件を考察し、この条件から Akizuki–Nakano vanishing が導かれることを説明する。また、この結果の混標数における類似についても紹介したい。
本講演は石塚彾氏との共同研究に基づく。
2026年07月01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
石倉麟太郎 氏 (東京大学大学院数理科学研究科)
On boundedness of the number of cuspidal automorphic representations of Mp(4) ordinary at p
石倉麟太郎 氏 (東京大学大学院数理科学研究科)
On boundedness of the number of cuspidal automorphic representations of Mp(4) ordinary at p
[ 講演概要 ]
The notion of ordinary modular forms, introduced and developed in Hida theory, has played a central role in the study of p-adic families of automorphic forms. It is therefore natural to ask how this notion extends to automorphic representations of covering groups. This talk is concerned with p-ordinary cuspidal automorphic representations of the metaplectic group Mp(4) with holomorphic discrete series at infinity. Using two Iwahori-level Hecke operators, we define an ordinary projector and investigate the conditions for a representation to be ordinary at p. Fixing the level K, we prove a bound (depending only on K) for the number of genuine cuspidal automorphic representations of Mp(4) ordinary at p and containing nonzero K-fixed vectors, as the holomorphic weight varies.
The notion of ordinary modular forms, introduced and developed in Hida theory, has played a central role in the study of p-adic families of automorphic forms. It is therefore natural to ask how this notion extends to automorphic representations of covering groups. This talk is concerned with p-ordinary cuspidal automorphic representations of the metaplectic group Mp(4) with holomorphic discrete series at infinity. Using two Iwahori-level Hecke operators, we define an ordinary projector and investigate the conditions for a representation to be ordinary at p. Fixing the level K, we prove a bound (depending only on K) for the number of genuine cuspidal automorphic representations of Mp(4) ordinary at p and containing nonzero K-fixed vectors, as the holomorphic weight varies.
2026年06月30日(火)
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/123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。
Sang-hyun Kim 氏 (Korea Institute For Advanced Study)
Structure and rigidity of manifold diffeomorphism groups (ENGLISH)
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。
Sang-hyun Kim 氏 (Korea Institute For Advanced Study)
Structure and rigidity of manifold diffeomorphism groups (ENGLISH)
[ 講演概要 ]
Given a manifold M and a structure S, we denote by Homeo(M;S) the group of S-preserving homeomorphisms of M. We will be particularly concerned with the case tha S is the C^r structure in the sense of Hölder continuity. In such a case, the group is written as Diff^r(M). The goal of this lecture series is to survey recent results and open questions on the rigidity of the group structures involving these groups. When M is a compact one-manifold, namely an interval or a circle, each real number r≥1 admits a finitely generated subgroup G_r of Diff^r(M) such that G_r never embeds into Diff^s(M) for any s>r. This generalizes observations by earlier foliation theorists on the case r=0 or r=1. In the second talk, I will propose a rigidity phenomenon regarding higher dimensional manifolds. Namely, we consider the question exactly when two manifold diffeomorphism groups Diff^r(M) and Diff^s(N) have the same logical structure. Modern findings regarding this question gives a generalization of classical results of Whittaker (1963), and of Takens-Filipkiewicz (1982). This talk is based on joint work with Thomas Koberda (UVa) and Javier de la Nuez-Gonzalez (KIAS).
[ 参考URL ]Given a manifold M and a structure S, we denote by Homeo(M;S) the group of S-preserving homeomorphisms of M. We will be particularly concerned with the case tha S is the C^r structure in the sense of Hölder continuity. In such a case, the group is written as Diff^r(M). The goal of this lecture series is to survey recent results and open questions on the rigidity of the group structures involving these groups. When M is a compact one-manifold, namely an interval or a circle, each real number r≥1 admits a finitely generated subgroup G_r of Diff^r(M) such that G_r never embeds into Diff^s(M) for any s>r. This generalizes observations by earlier foliation theorists on the case r=0 or r=1. In the second talk, I will propose a rigidity phenomenon regarding higher dimensional manifolds. Namely, we consider the question exactly when two manifold diffeomorphism groups Diff^r(M) and Diff^s(N) have the same logical structure. Modern findings regarding this question gives a generalization of classical results of Whittaker (1963), and of Takens-Filipkiewicz (1982). This talk is based on joint work with Thomas Koberda (UVa) and Javier de la Nuez-Gonzalez (KIAS).
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
2026年06月29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
Chin-Yu Hsiao 氏 (国立台湾大学)
Heat kernel asymptotics for the $\bar{\partial}$-Neumann Laplacian on manifolds with boundary (English)
https://forms.gle/8ERsVDLuKHwbVzm57
Chin-Yu Hsiao 氏 (国立台湾大学)
Heat kernel asymptotics for the $\bar{\partial}$-Neumann Laplacian on manifolds with boundary (English)
[ 講演概要 ]
We study the heat kernel asymptotics of the $\bar{\partial}$-Neumann Laplacian associated with high tensor powers of a holomorphic line bundle. Specifically, for a relatively compact complex submanifold with smooth boundary in a complex manifold, we consider the $\bar{\partial}$-Neumann Laplacian acting on holomorphic sections of a holomorphic bundle over the submanifold. As the tensor power of the line bundle approaches infinity, we obtain explicit asymptotic expansions of the heat kernel in the submanifold's interior, on its boundary, and near the boundary. This is achieved by explicitly solving the heat equation for the weighted $\bar{\partial}$-Neumann Laplacian in domains that are not necessarily strongly pseudoconvex and showing uniform convergence of the associated scaled Laplacian's heat kernel to this solution. As an application, we establish analogue holomorphic Morse inequalities of Demailly on complex manifolds with boundary.
[ 参考URL ]We study the heat kernel asymptotics of the $\bar{\partial}$-Neumann Laplacian associated with high tensor powers of a holomorphic line bundle. Specifically, for a relatively compact complex submanifold with smooth boundary in a complex manifold, we consider the $\bar{\partial}$-Neumann Laplacian acting on holomorphic sections of a holomorphic bundle over the submanifold. As the tensor power of the line bundle approaches infinity, we obtain explicit asymptotic expansions of the heat kernel in the submanifold's interior, on its boundary, and near the boundary. This is achieved by explicitly solving the heat equation for the weighted $\bar{\partial}$-Neumann Laplacian in domains that are not necessarily strongly pseudoconvex and showing uniform convergence of the associated scaled Laplacian's heat kernel to this solution. As an application, we establish analogue holomorphic Morse inequalities of Demailly on complex manifolds with boundary.
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
15:20〜 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。
野田 涼一郎 氏 (早稲田大学)
Fine geometry of collision measures
15:20〜 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。
野田 涼一郎 氏 (早稲田大学)
Fine geometry of collision measures
[ 講演概要 ]
Given several independent stochastic processes, their collision measure is a random measure that records when and where they collide. In this talk, I will discuss fine geometric properties of collision measures for independent Markov processes on metric measure spaces. Under standard heat kernel estimates, we identify the local dimensions of the temporal and spatial marginals of the collision measure. We also determine the Hausdorff dimensions of their supports, as well as those of the corresponding sets of collision times and collision sites. Finally, we study logarithmic limsup gauges describing typical and thick collision times and sites.
Given several independent stochastic processes, their collision measure is a random measure that records when and where they collide. In this talk, I will discuss fine geometric properties of collision measures for independent Markov processes on metric measure spaces. Under standard heat kernel estimates, we identify the local dimensions of the temporal and spatial marginals of the collision measure. We also determine the Hausdorff dimensions of their supports, as well as those of the corresponding sets of collision times and collision sites. Finally, we study logarithmic limsup gauges describing typical and thick collision times and sites.
2026年06月26日(金)
談話会・数理科学講演会
15:30-16:30 数理科学研究科棟(駒場) NISSAY Lecture Hall号室
ベズ ニール 氏 (東京大学大学院数理科学研究科)
掛谷予想とBrascamp-Lieb不等式 (日本語)
ベズ ニール 氏 (東京大学大学院数理科学研究科)
掛谷予想とBrascamp-Lieb不等式 (日本語)
[ 講演概要 ]
掛谷予想は、表向きは幾何学的測度論の問題であるにもかかわらず、
現代のフーリエ解析において極めて重要な役割を果たしています。
本講演では、このつながりについて議論した後、
この文脈におけるBrascamp-Lieb不等式の重要性を説明し、
同不等式の理論における最近の進展について紹介します。
掛谷予想は、表向きは幾何学的測度論の問題であるにもかかわらず、
現代のフーリエ解析において極めて重要な役割を果たしています。
本講演では、このつながりについて議論した後、
この文脈におけるBrascamp-Lieb不等式の重要性を説明し、
同不等式の理論における最近の進展について紹介します。
幾何解析セミナー
13:30-14;30 数理科学研究科棟(駒場) 002号室
Federica Dragoni 氏 (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 氏 (Cardiff University)
Convexity: from the Euclidean space to Riemannian and sub-Riemannian manifolds (英語)
[ 講演概要 ]
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.
[ 参考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/
統計数学セミナー
13:30-14:30 数理科学研究科棟(駒場) 122号室
ハイブリッド開催
Prof. Hsin-Hsiung 'Bill’ Huang 氏 (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
ハイブリッド開催
Prof. Hsin-Hsiung 'Bill’ Huang 氏 (School of Data, Mathematical, and Statistical Sciences, University of Central Florida)
Scalable Bayesian Conformal Inference for High-Dimensional Spatiotemporal Zero-Inflated Count Data (English)
[ 講演概要 ]
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.
[ 参考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年06月25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
Xiao Dongyuan 氏 (東北大学)
Complete classification of traveling wave solutions to monotone dynamical systems (Japanese)
Xiao Dongyuan 氏 (東北大学)
Complete classification of traveling wave solutions to monotone dynamical systems (Japanese)
[ 講演概要 ]
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年06月23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
Ravi Mistry 氏 (東大数理)
Knots, Invariants, QFT, and Beyond
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Ravi Mistry 氏 (東大数理)
Knots, Invariants, QFT, and Beyond
[ 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。
Andrei Pajitnov 氏 (Université de Nantes)
Morse-Novikov theory for links (ENGLISH)
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。
Andrei Pajitnov 氏 (Université de Nantes)
Morse-Novikov theory for links (ENGLISH)
[ 講演概要 ]
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.
[ 参考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年06月22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
オンライン開催のみ。対面での開催はありません。
四ッ谷 直仁 氏 (静岡大学/IMAG, モンペリエ大学)
Secondary polytopes of spherical varieties (Japanese)
https://forms.gle/8ERsVDLuKHwbVzm57
オンライン開催のみ。対面での開催はありません。
四ッ谷 直仁 氏 (静岡大学/IMAG, モンペリエ大学)
Secondary polytopes of spherical varieties (Japanese)
[ 講演概要 ]
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.
[ 参考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
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。
永津 愛彩 氏 (京都大学)
Large $N$ expansion for smooth multi-trace spectral statistics of
classical matrix ensembles, central limit theorems and matrix integrals.
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。
永津 愛彩 氏 (京都大学)
Large $N$ expansion for smooth multi-trace spectral statistics of
classical matrix ensembles, central limit theorems and matrix integrals.
[ 講演概要 ]
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年06月18日(木)
基礎論セミナー
15:30-17:30 数理科学研究科棟(駒場) 122号室
Paul Larson 氏 (Miami University)
Discontinuous homomorphisms without Hamel bases
Paul Larson 氏 (Miami University)
Discontinuous homomorphisms without Hamel bases
[ 講演概要 ]
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年06月16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
石倉宙樹 氏 (京大数理研)
Borel planar complexes and soficity
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
石倉宙樹 氏 (京大数理研)
Borel planar complexes and soficity
[ 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/128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。
森脇 湧登 氏 (理化学研究所数理創造研究センター)
共形平坦因子化ホモロジー (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。
森脇 湧登 氏 (理化学研究所数理創造研究センター)
共形平坦因子化ホモロジー (JAPANESE)
[ 講演概要 ]
本講演では、Lurie の因子化ホモロジーの共形リーマン幾何類似として導入された、共形平坦因子化ホモロジーを紹介する。
通常の因子化ホモロジーは、d-disk 代数を入力として、d次元多様体の計量に依存しない不変量を与える。これに対し、共形平坦因子化ホモロジーでは、disk の共形埋め込みのなす operad の代数である共形平坦 d-disk 代数を入力とし、その左 Kan 拡張により、共形平坦リーマン多様体の計量に依存した不変量を構成する。
この理論は、局所的な共形変換の表現とリーマン幾何的な不変量を結びつける枠組みを与え、d次元の共形場理論の局所構造を記述するものである。講演では、2次元の場合には Bergman 空間と Grunsky 作用素、3次元以上の場合には SO+(d,1) のユニタリ表現を用いて構成される具体例についても説明する。
本講演は arXiv:2602.08729 および arXiv:2603.06491に基づく。
[ 参考URL ]本講演では、Lurie の因子化ホモロジーの共形リーマン幾何類似として導入された、共形平坦因子化ホモロジーを紹介する。
通常の因子化ホモロジーは、d-disk 代数を入力として、d次元多様体の計量に依存しない不変量を与える。これに対し、共形平坦因子化ホモロジーでは、disk の共形埋め込みのなす operad の代数である共形平坦 d-disk 代数を入力とし、その左 Kan 拡張により、共形平坦リーマン多様体の計量に依存した不変量を構成する。
この理論は、局所的な共形変換の表現とリーマン幾何的な不変量を結びつける枠組みを与え、d次元の共形場理論の局所構造を記述するものである。講演では、2次元の場合には Bergman 空間と Grunsky 作用素、3次元以上の場合には SO+(d,1) のユニタリ表現を用いて構成される具体例についても説明する。
本講演は arXiv:2602.08729 および arXiv:2603.06491に基づく。
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
2026年06月15日(月)
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。
一場 知之 氏 (University of California Santa Barbara)
Feynman formula for discrete-time quantum walk and its applications
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。
一場 知之 氏 (University of California Santa Barbara)
Feynman formula for discrete-time quantum walk and its applications
[ 講演概要 ]
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.
日仏数学拠点FJ-LMIセミナー
10:30-12:00 数理科学研究科棟(駒場) 002号室
Eric Leclerc, . Fabrizio Cleri, Yuki Miura, Stephane Poulain 氏 (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 氏 (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)
[ 講演概要 ]
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.
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