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過去の記録 ～05/17｜本日 05/18 | 今後の予定 05/19～
2026年05月19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
上川弘郎 氏 (京都大学)
The homotopy groups of the automorphism group of Kirchberg algebras with compact group actions
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
上川弘郎 氏 (京都大学)
The homotopy groups of the automorphism group of Kirchberg algebras with compact group actions
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
PDE実解析研究会
10:30-11:30 数理科学研究科棟(駒場) 128号室
通常の会場と異なります。
浜向 直 氏 (北海道大学 大学院理学研究院)
対数凹関数に対するGagliardo-Nirenberg型不等式と非線形楕円型固有値問題への応用 (日本語)
通常の会場と異なります。
浜向 直 氏 (北海道大学 大学院理学研究院)
対数凹関数に対するGagliardo-Nirenberg型不等式と非線形楕円型固有値問題への応用 (日本語)
[ 講演概要 ]
Gagliardo-Nirenberg型不等式を、遠方で減衰する対数凹関数に対して導きます。証明では、関数から定まるエントロピーに対する上下からの評価が鍵となります。上からの評価には対数型ソボレフの不等式、下からの評価には関数の対数凹性を利用します。また、得られたGagliardo-Nirenberg型不等式における定数の精度についても議論します。さらに、完全非線形楕円型固有値問題の解に適用して、固有値に対する下からの評価を導きます。本講演の内容は、藤田安啓氏、五十嵐蓮氏との共同研究に基づきます。
Gagliardo-Nirenberg型不等式を、遠方で減衰する対数凹関数に対して導きます。証明では、関数から定まるエントロピーに対する上下からの評価が鍵となります。上からの評価には対数型ソボレフの不等式、下からの評価には関数の対数凹性を利用します。また、得られたGagliardo-Nirenberg型不等式における定数の精度についても議論します。さらに、完全非線形楕円型固有値問題の解に適用して、固有値に対する下からの評価を導きます。本講演の内容は、藤田安啓氏、五十嵐蓮氏との共同研究に基づきます。
トポロジー火曜セミナー
17:30-18:30 数理科学研究科棟(駒場) hybrid/056号室
Lie群論・表現論セミナーと合同開催。 参加を希望される場合は、セミナーのウェブページをご覧下さい。
森田 陽介 氏 (九州大学)
Compact Clifford-Klein forms and homotopy theory of sphere bundles (JAPANESE)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Lie群論・表現論セミナーと合同開催。 参加を希望される場合は、セミナーのウェブページをご覧下さい。
森田 陽介 氏 (九州大学)
Compact Clifford-Klein forms and homotopy theory of sphere bundles (JAPANESE)
[ 講演概要 ]
Let G/H be a homogeneous space of reductive type (such as the pseudo-Riemannian hyperbolic space H^{p,q}). If a discrete subgroup of G acts properly and freely on G/H, the quotient space becomes a manifold locally modelled on G/H and is called a Clifford-Klein form. In this talk, I will explain a new necessary condition on G/H for the existence of compact Clifford-Klein forms, formulated in terms of homotopy theory of sphere bundles. Our theorem and Adams's solution to the 'vector fields on sphere' problem (1962) together imply the following result: unless p is divisible by 2^{ν(q)}, there does not exist a compact complete pseudo-Riemannian manifolds of signature (p,q) with constant negative sectional curvature. Here, ν(q) is an explicit natural number roughly equal to q/2. This is joint work with Fanny Kassel and Nicolas Tholozan.
[ 参考URL ]Let G/H be a homogeneous space of reductive type (such as the pseudo-Riemannian hyperbolic space H^{p,q}). If a discrete subgroup of G acts properly and freely on G/H, the quotient space becomes a manifold locally modelled on G/H and is called a Clifford-Klein form. In this talk, I will explain a new necessary condition on G/H for the existence of compact Clifford-Klein forms, formulated in terms of homotopy theory of sphere bundles. Our theorem and Adams's solution to the 'vector fields on sphere' problem (1962) together imply the following result: unless p is divisible by 2^{ν(q)}, there does not exist a compact complete pseudo-Riemannian manifolds of signature (p,q) with constant negative sectional curvature. Here, ν(q) is an explicit natural number roughly equal to q/2. This is joint work with Fanny Kassel and Nicolas Tholozan.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Lie群論・表現論セミナー
17:30-18:30 数理科学研究科棟(駒場) 056号室
トポロジー火曜セミナーと合同開催。
森田陽介 氏 (九州大学)
Compact Clifford-Klein forms and homotopy theory of sphere bundles (Japanese)
トポロジー火曜セミナーと合同開催。
森田陽介 氏 (九州大学)
Compact Clifford-Klein forms and homotopy theory of sphere bundles (Japanese)
[ 講演概要 ]
Let G/H be a homogeneous space of reductive type (such as the pseudo-Riemannian hyperbolic space H^{p,q}). If a discrete subgroup of G acts properly and freely on G/H, the quotient space becomes a manifold locally modelled on G/H and is called a Clifford-Klein form. In this talk, I will explain a new necessary condition on G/H for the existence of compact Clifford-Klein forms, formulated in terms of homotopy theory of sphere bundles. Our theorem and Adams's solution to the ‘vector fields on sphere’ problem (1962) together imply the following result: unless p is divisible by 2^{ν(q)}, there does not exist a compact complete pseudo-Riemannian manifolds of signature (p,q) with constant negative sectional curvature. Here, ν(q) is an explicit natural number roughly equal to q/2. This is joint work with Fanny Kassel and Nicolas Tholozan.
Let G/H be a homogeneous space of reductive type (such as the pseudo-Riemannian hyperbolic space H^{p,q}). If a discrete subgroup of G acts properly and freely on G/H, the quotient space becomes a manifold locally modelled on G/H and is called a Clifford-Klein form. In this talk, I will explain a new necessary condition on G/H for the existence of compact Clifford-Klein forms, formulated in terms of homotopy theory of sphere bundles. Our theorem and Adams's solution to the ‘vector fields on sphere’ problem (1962) together imply the following result: unless p is divisible by 2^{ν(q)}, there does not exist a compact complete pseudo-Riemannian manifolds of signature (p,q) with constant negative sectional curvature. Here, ν(q) is an explicit natural number roughly equal to q/2. This is joint work with Fanny Kassel and Nicolas Tholozan.
2026年05月20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
毛塚 由佳子 氏 (東京大学大学院数理科学研究科)
Special values of $L$-functions and the Birch and Swinnerton-Dyer conjecture for CM elliptic curves
https://www.ms.u-tokyo.ac.jp/~kezuka/
毛塚 由佳子 氏 (東京大学大学院数理科学研究科)
Special values of $L$-functions and the Birch and Swinnerton-Dyer conjecture for CM elliptic curves
[ 講演概要 ]
Elliptic curves with complex multiplication (CM) have long served as some of the most powerful examples for understanding the Birch and Swinnerton-Dyer (BSD) conjecture. In particular, a wide range of arithmetic phenomena has been observed in families of quadratic twists of these curves. In this talk, I will explain how CM elliptic curves have been used to advance our understanding of the conjecture, and discuss some current directions in this area, focusing in particular on Iwasawa theory and recent developments involving the Gross family of elliptic curves.
[ 参考URL ]Elliptic curves with complex multiplication (CM) have long served as some of the most powerful examples for understanding the Birch and Swinnerton-Dyer (BSD) conjecture. In particular, a wide range of arithmetic phenomena has been observed in families of quadratic twists of these curves. In this talk, I will explain how CM elliptic curves have been used to advance our understanding of the conjecture, and discuss some current directions in this area, focusing in particular on Iwasawa theory and recent developments involving the Gross family of elliptic curves.
https://www.ms.u-tokyo.ac.jp/~kezuka/
2026年05月22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
Justin Sawon 氏 (University of North Carolina Chapel Hill)
Classification results for Lagrangian fibrations
Justin Sawon 氏 (University of North Carolina Chapel Hill)
Classification results for Lagrangian fibrations
[ 講演概要 ]
A Lagrangian fibration on a holomorphic symplectic manifold or variety is one whose general fibre is an abelian variety that is Lagrangian with respect to the symplectic form. Examples were constructed by Beauville/Mukai whose fibres are Jacobians of curves, and by Markushevich-Tikhomirov, Arbarella-Sacca-Ferretti, Matteini, S-Shen, and Brakkee-Camere-Grossi-Pertusi-Sacca-Viktorova whose fibres are Prym varieties of curves with involutions. In all of these examples the family of curves is a linear system on a K3 surface, suggesting the question: is this always the case? Markushevich answered this affirmatively in the genus two case: if the relative compactified Jacobian of a family of genus two curves is a Lagrangian fibration then the curves all lie on a K3 surface, and the Lagrangian fibration is a Beauville-Mukai system. In this talk I will describe our generalization of this result to higher genus, and also to relative Prym varieties of genus three covers with involutions (joint work with Xuqiang Qin).
A Lagrangian fibration on a holomorphic symplectic manifold or variety is one whose general fibre is an abelian variety that is Lagrangian with respect to the symplectic form. Examples were constructed by Beauville/Mukai whose fibres are Jacobians of curves, and by Markushevich-Tikhomirov, Arbarella-Sacca-Ferretti, Matteini, S-Shen, and Brakkee-Camere-Grossi-Pertusi-Sacca-Viktorova whose fibres are Prym varieties of curves with involutions. In all of these examples the family of curves is a linear system on a K3 surface, suggesting the question: is this always the case? Markushevich answered this affirmatively in the genus two case: if the relative compactified Jacobian of a family of genus two curves is a Lagrangian fibration then the curves all lie on a K3 surface, and the Lagrangian fibration is a Beauville-Mukai system. In this talk I will describe our generalization of this result to higher genus, and also to relative Prym varieties of genus three covers with involutions (joint work with Xuqiang Qin).
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
Evgeny Shinder 氏 (University of Sheffield / 東京大学大学院数理科学研究科)
Gromov's cancellation question in birational algebraic geometry
Evgeny Shinder 氏 (University of Sheffield / 東京大学大学院数理科学研究科)
Gromov's cancellation question in birational algebraic geometry
[ 講演概要 ]
Gromov's 1999 cancellation question is: given two open embeddings of a variety U into a variety X, do they always have isomorphic closed complements? In my joint work with Hsueh-Yung Lin we reformulate this question in terms of the structure of the Grothendieck ring of varieties and answer it in various situations. The answer will be positive or negative depending on the dimension of varieties and the ground field. Finally, I will present an application to the structure of the Cremona group of birational self-maps of the projective space.
Gromov's 1999 cancellation question is: given two open embeddings of a variety U into a variety X, do they always have isomorphic closed complements? In my joint work with Hsueh-Yung Lin we reformulate this question in terms of the structure of the Grothendieck ring of varieties and answer it in various situations. The answer will be positive or negative depending on the dimension of varieties and the ground field. Finally, I will present an application to the structure of the Cremona group of birational self-maps of the projective space.
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.
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 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 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
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)
TBA
厚東 裕紀 氏 (Academia Sinica)
TBA
[ 講演概要 ]
TBA
TBA
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)
(Japanese)
[ 参考URL ]
https://forms.gle/8ERsVDLuKHwbVzm57
小森 洋平 氏 (早稲田大学)
(Japanese)
[ 参考URL ]
https://forms.gle/8ERsVDLuKHwbVzm57
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
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.
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.
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)
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.
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.
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)
TBA
Luc PIRIO 氏 (CNRS FJ-LMI)
TBA
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
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.
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.
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
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)
TBA
Young-Hoon Kiem 氏 (Korea Institute for Advanced Study)
TBA
[ 講演概要 ]
TBA
TBA
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 results are obtained in different forms and remain somewhat scattered.
In this talk, I would like to present a relative version of Thom polynomial theory that places them in a unified framework. First, we introduce Thom polynomials relative to maps prescribed near the boundary, based on Steenrod's obstruction theory. Next, we show a structure theorem of Thom polynomials relative to framed immersions, using Kervaire's relative characteristic classes. Finally, we reinterpret earlier formulas within our framework, and also recover and generalize some of them, including Némethi--Pintér's formula for immersions associated with singular map-germs.
[ 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 results are obtained in different forms and remain somewhat scattered.
In this talk, I would like to present a relative version of Thom polynomial theory that places them in a unified framework. First, we introduce Thom polynomials relative to maps prescribed near the boundary, based on Steenrod's obstruction theory. Next, we show a structure theorem of Thom polynomials relative to framed immersions, using Kervaire's relative characteristic classes. Finally, we reinterpret earlier formulas within our framework, and also recover and generalize some of them, including Némethi--Pintér's formula for immersions associated with singular map-germs.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
