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Seminar information archive
Seminar information archive ～04/26｜Today's seminar 04/27 | Future seminars 04/28～
2026/04/24
Colloquium
15:30-16:30 Room #NISSAY Lecture Hall(大講義室) (Graduate School of Math. Sci. Bldg.)
Yukako Kezuka (Graduate School of Mathematical Sciences, The University of Tokyo)
A Birch–Swinnerton-Dyer dichotomy (日本語)
Yukako Kezuka (Graduate School of Mathematical Sciences, The University of Tokyo)
A Birch–Swinnerton-Dyer dichotomy (日本語)
[ Abstract ]
The aim of this talk is to explore a possible weakening of the Birch–Swinnerton-Dyer conjecture, framed as a dichotomy, in which neither the equality of the analytic and Mordell–Weil ranks nor the finiteness of the Tate–Shafarevich group is assumed to hold individually, but rather that if one fails, then so does the other – and in a very specific way. We will explain our motivations coming from (1) the analogy with Iwasawa theory, (2) connections with known results onelliptic curves, and (3) comparison with the function field case.
This talk is based on joint work with Don Zagier (MPIM Bonn).
The aim of this talk is to explore a possible weakening of the Birch–Swinnerton-Dyer conjecture, framed as a dichotomy, in which neither the equality of the analytic and Mordell–Weil ranks nor the finiteness of the Tate–Shafarevich group is assumed to hold individually, but rather that if one fails, then so does the other – and in a very specific way. We will explain our motivations coming from (1) the analogy with Iwasawa theory, (2) connections with known results onelliptic curves, and (3) comparison with the function field case.
This talk is based on joint work with Don Zagier (MPIM Bonn).
2026/04/22
Seminar on Mathematics for various disciplines
10:30-11:30 Room #056 (Graduate School of Math. Sci. Bldg.)
Hidekazu Yoshioka (Japan Advanced Institute of Science and Technology)
Non-standard mathematical models for a deeper understanding of aquatic environments (日本語)
Hidekazu Yoshioka (Japan Advanced Institute of Science and Technology)
Non-standard mathematical models for a deeper understanding of aquatic environments (日本語)
2026/04/21
Tuesday Seminar on Topology
16:00-17:00 Online
Pre-registration required. See our seminar webpage.
Masaki Taniguchi (Kyoto University)
Exotic diffeomorphisms on a contractible 4-manifold surviving two stabilization (JAPANESE)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Pre-registration required. See our seminar webpage.
Masaki Taniguchi (Kyoto University)
Exotic diffeomorphisms on a contractible 4-manifold surviving two stabilization (JAPANESE)
[ Abstract ]
Wall's stabilization principle suggests that exotic phenomena in dimension four in the orientable category disappear after taking connected sums with sufficiently many S2xS2. Since most known exotic pairs of closed 4-manifolds become diffeomorphic after one stabilization, a natural question was: is a single S2xS2 enough? Recently, Jianfeng Lin constructed an exotic diffeomorphism on a closed 4-manifold-a diffeomorphism topologically isotopic to the identity but not smoothly isotopic-that survives one stabilization. In this talk, we provide a relative exotic diffeomorphism on a compact contractible 4-manifold that survives two stabilizations. This gives the first exotic phenomenon in the orientable category that survives two stabilizations. This is joint work with Sungkyung Kang and Junghwan Park.
[ Reference URL ]Wall's stabilization principle suggests that exotic phenomena in dimension four in the orientable category disappear after taking connected sums with sufficiently many S2xS2. Since most known exotic pairs of closed 4-manifolds become diffeomorphic after one stabilization, a natural question was: is a single S2xS2 enough? Recently, Jianfeng Lin constructed an exotic diffeomorphism on a closed 4-manifold-a diffeomorphism topologically isotopic to the identity but not smoothly isotopic-that survives one stabilization. In this talk, we provide a relative exotic diffeomorphism on a compact contractible 4-manifold that survives two stabilizations. This gives the first exotic phenomenon in the orientable category that survives two stabilizations. This is joint work with Sungkyung Kang and Junghwan Park.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Operator Algebra Seminars
16:45-18:15 Room #126 (Graduate School of Math. Sci. Bldg.)
Ayoub Hafid (Univ. Tokyo)
Concepts of coarse geometry on quantum metric spaces
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Ayoub Hafid (Univ. Tokyo)
Concepts of coarse geometry on quantum metric spaces
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
2026/04/20
Seminar on Geometric Complex Analysis
10:30-12:00 Room #126 (Graduate School of Math. Sci. Bldg.)
Yusaku Tiba (Ochanomizu Univ.)
$C^{\ell}$-estimates for the $\overline{\partial}$-equation on high tensor powers of positive line bundles (Japanese)
https://forms.gle/8ERsVDLuKHwbVzm57
Yusaku Tiba (Ochanomizu Univ.)
$C^{\ell}$-estimates for the $\overline{\partial}$-equation on high tensor powers of positive line bundles (Japanese)
[ Abstract ]
Let $M$ be a compact complex manifold, $L$ be a positive holomorphic line bundle over $M$, and $E$ be a holomorphic vector bundle over $M$. It is known that the cohomology groups $H^i(M, L^k \otimes E)$ vanish for $i > 0$ when $k$ is sufficiently large. This vanishing theorem is typically proved by solving the $\overline{\partial}$-equation using H\"ormander’s $L^2$-estimates in the complex geometry. In this talk, we solve the $\overline{\partial}$-equation not by H\"ormander’s method, but by means of weighted integral formulas. In particular, we apply the weighted integral formula of Andersson--Berndtsson (1982) in a semi-classical setting and obtain $C^{\ell}$-norm estimates for solutions of the $\overline{\partial}$-equation.
[ Reference URL ]Let $M$ be a compact complex manifold, $L$ be a positive holomorphic line bundle over $M$, and $E$ be a holomorphic vector bundle over $M$. It is known that the cohomology groups $H^i(M, L^k \otimes E)$ vanish for $i > 0$ when $k$ is sufficiently large. This vanishing theorem is typically proved by solving the $\overline{\partial}$-equation using H\"ormander’s $L^2$-estimates in the complex geometry. In this talk, we solve the $\overline{\partial}$-equation not by H\"ormander’s method, but by means of weighted integral formulas. In particular, we apply the weighted integral formula of Andersson--Berndtsson (1982) in a semi-classical setting and obtain $C^{\ell}$-norm estimates for solutions of the $\overline{\partial}$-equation.
https://forms.gle/8ERsVDLuKHwbVzm57
2026/04/14
Tuesday Seminar of Analysis
16:00-17:30 Room # 002 (Graduate School of Math. Sci. Bldg.)
Nicola Fusco (University of Naples Federico II)
Consistency for the surface diffusion flow in three dimensions (English)
Nicola Fusco (University of Naples Federico II)
Consistency for the surface diffusion flow in three dimensions (English)
[ Abstract ]
We will discuss the flat flow solution for the surface diffusion equation via a discrete minimizing movements scheme proposed in 1994 in a celebrated paper by J.W. Cahn and J.E. Taylor. We will show that in dimension three the scheme converges to the unique smooth solution of the equation, provided the initial set is sufficiently regular. Joint paper with Marco Cicalese, Vesa Julin and Andrea Kubin.
We will discuss the flat flow solution for the surface diffusion equation via a discrete minimizing movements scheme proposed in 1994 in a celebrated paper by J.W. Cahn and J.E. Taylor. We will show that in dimension three the scheme converges to the unique smooth solution of the equation, provided the initial set is sufficiently regular. Joint paper with Marco Cicalese, Vesa Julin and Andrea Kubin.
Tuesday Seminar on Topology
16:00-17:30 Room #hybrid/056 (Graduate School of Math. Sci. Bldg.)
Pre-registration required. See our seminar webpage.
Yukihiro Okamoto (Tokyo Metropolitan University)
Non-contractible loops of Legendrian tori from families of knots (JAPANESE)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Pre-registration required. See our seminar webpage.
Yukihiro Okamoto (Tokyo Metropolitan University)
Non-contractible loops of Legendrian tori from families of knots (JAPANESE)
[ Abstract ]
The unit cotangent bundle of the Euclidean space R3 has a canonical contact structure. In this talk, we discuss loops of Legendrian tori in this 5-dimensional contact manifold. In particular, we focus on loops arising as families of the unit conormal bundles of knots in R3, and I will explain a topological method to compute the monodromy on the Legendrian contact homology in degree 0 induced by those loops. As an application, we get examples of non-contractible loops of Legendrian tori which are contractible in the space of smoothly embedded tori. This is joint work with Marián Poppr.
[ Reference URL ]The unit cotangent bundle of the Euclidean space R3 has a canonical contact structure. In this talk, we discuss loops of Legendrian tori in this 5-dimensional contact manifold. In particular, we focus on loops arising as families of the unit conormal bundles of knots in R3, and I will explain a topological method to compute the monodromy on the Legendrian contact homology in degree 0 induced by those loops. As an application, we get examples of non-contractible loops of Legendrian tori which are contractible in the space of smoothly embedded tori. This is joint work with Marián Poppr.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Operator Algebra Seminars
16:45-18:15 Room #126 (Graduate School of Math. Sci. Bldg.)
Akihiko Arai (Chiba University)
On the isomorphism problem for ultraproducts of $C^*$-algebras in continuous model theory
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Akihiko Arai (Chiba University)
On the isomorphism problem for ultraproducts of $C^*$-algebras in continuous model theory
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
2026/04/13
Tokyo Probability Seminar
16:00-17:30 Room #126 (Graduate School of Math. Sci. Bldg.)
We are having teatime from 15:20 in the common room on the second floor. Please join us.
Daisuke Shiraishi (Kyoto University)
4次元単純ランダムウォークの交叉と長距離パーコレーションの関係
We are having teatime from 15:20 in the common room on the second floor. Please join us.
Daisuke Shiraishi (Kyoto University)
4次元単純ランダムウォークの交叉と長距離パーコレーションの関係
[ Abstract ]
よく知られているように、4次元ブラウン運動の軌跡は単純曲線になる。一方で4次元単純ランダムウォークの軌跡は、ループ除去ランダムウォークの長さに非自明な対数項が現れる程度のループを持つ。本講演では、4次元単純ランダムウォークの軌跡の交叉とある長距離パーコレーションモデルとの関係性について解説する。
よく知られているように、4次元ブラウン運動の軌跡は単純曲線になる。一方で4次元単純ランダムウォークの軌跡は、ループ除去ランダムウォークの長さに非自明な対数項が現れる程度のループを持つ。本講演では、4次元単純ランダムウォークの軌跡の交叉とある長距離パーコレーションモデルとの関係性について解説する。
Seminar on Geometric Complex Analysis
10:30-12:00 Room #126 (Graduate School of Math. Sci. Bldg.)
Taito Shimoji (Univ. of Osaka)
On the nilpotent quasi-projective groups (Japanese)
https://forms.gle/8ERsVDLuKHwbVzm57
Taito Shimoji (Univ. of Osaka)
On the nilpotent quasi-projective groups (Japanese)
[ Abstract ]
The quasi-projective groups are the fundamental groups of smooth quasi-projective complex varieties. Aguilar and Campana provided the problem about the torsion-free nilpotent quasi-projective groups. The problem asks whether such groups are 2-step nilpotent or abelian groups(arXiv:2301.11232,Question26). In this talk, I introduce some my result related to the torsion-free nilpotent quasi-projective groups and the above question. In particular, the latest result suggests the existence of torsion-free nilpotent quasi-projective groups with three or more steps.
[ Reference URL ]The quasi-projective groups are the fundamental groups of smooth quasi-projective complex varieties. Aguilar and Campana provided the problem about the torsion-free nilpotent quasi-projective groups. The problem asks whether such groups are 2-step nilpotent or abelian groups(arXiv:2301.11232,Question26). In this talk, I introduce some my result related to the torsion-free nilpotent quasi-projective groups and the above question. In particular, the latest result suggests the existence of torsion-free nilpotent quasi-projective groups with three or more steps.
https://forms.gle/8ERsVDLuKHwbVzm57
2026/04/10
Geometric Analysis Seminar
16:00-17:00 Room #056 (Graduate School of Math. Sci. Bldg.)
Shinichiroh Matsuo (Nagoya University)
Discretization of Dirac operators and lattice gauge theory (日本語)
https://sites.google.com/g.ecc.u-tokyo.ac.jp/geometricanalysisseminar/
Shinichiroh Matsuo (Nagoya University)
Discretization of Dirac operators and lattice gauge theory (日本語)
[ Abstract ]
Our ultimate goal is to discretize Seiberg-Witten theory.
Considering PL = DIFF in dimension four, we would like to construct something like PL Seiberg-Witten theory.
As a first step towards this goal, we study the discretization of the analytic index of Dirac operators.
However, the analytic index of Fredholm operators is an essentially infinite-dimensional phenomenon, while the index theory of finite-dimensional self-adjoint operators is trivial.
Thus, a naive discretization of Dirac operators does not work.
In this talk, I will explain how the “Wilson-Dirac operator” from lattice gauge theory provides a correct discretization, at least from the viewpoint of the analytic index.
This talk is based on a joint work with Shoto Aoki, Hidenori Fukaya, Mikio Furuta, Tetsuya Oonogi, and Satoshi Yamaguchi.
https://arxiv.org/abs/2602.12576
https://arxiv.org/abs/2407.17708
[ Reference URL ]Our ultimate goal is to discretize Seiberg-Witten theory.
Considering PL = DIFF in dimension four, we would like to construct something like PL Seiberg-Witten theory.
As a first step towards this goal, we study the discretization of the analytic index of Dirac operators.
However, the analytic index of Fredholm operators is an essentially infinite-dimensional phenomenon, while the index theory of finite-dimensional self-adjoint operators is trivial.
Thus, a naive discretization of Dirac operators does not work.
In this talk, I will explain how the “Wilson-Dirac operator” from lattice gauge theory provides a correct discretization, at least from the viewpoint of the analytic index.
This talk is based on a joint work with Shoto Aoki, Hidenori Fukaya, Mikio Furuta, Tetsuya Oonogi, and Satoshi Yamaguchi.
https://arxiv.org/abs/2602.12576
https://arxiv.org/abs/2407.17708
https://sites.google.com/g.ecc.u-tokyo.ac.jp/geometricanalysisseminar/
2026/04/08
Tokyo-Nagoya Algebra Seminar
13:00-14:30 Online
Ryu Tomonaga (The University of Tokyo)
d-無限表現型代数と射影多様体の導来同値について (Japanese)
[ Reference URL ]
https://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
Ryu Tomonaga (The University of Tokyo)
d-無限表現型代数と射影多様体の導来同値について (Japanese)
[ Reference URL ]
https://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
2026/04/07
Tuesday Seminar on Topology
16:00-17:30 Room #hybrid/056 (Graduate School of Math. Sci. Bldg.)
Pre-registration required. See our seminar webpage.
Tatsumasa Suzuki (The University of Tokyo)
Price twist and pochette surgery constructing non-simply connected closed 4-manifolds (JAPANESE)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Pre-registration required. See our seminar webpage.
Tatsumasa Suzuki (The University of Tokyo)
Price twist and pochette surgery constructing non-simply connected closed 4-manifolds (JAPANESE)
[ Abstract ]
A cut-and-paste operation along an embedded real projective plane in a 4-manifold is called a Price twist. A Price twist on the 4-sphere produces, up to diffeomorphism, at most three 4-manifolds: the 4-sphere itself, a homotopy 4-sphere, and a non-simply connected closed 4-manifold. In general, the classification of diffeomorphism types of non-simply connected closed 4-manifolds is still far from being well understood. In this talk, we focus on Price twists on the 4-sphere associated with embeddings of the real projective plane of Kinoshita type that yield non-simply connected 4-manifolds. We present several properties of these manifolds and results on the classification of their diffeomorphism types. We also explain pochette surgery, introduced by Zjuñici Iwase and Yukio Matsumoto, which is closely related to the results of this work. This talk is based on joint work with Tsukasa Isoshima (Keio University).
[ Reference URL ]A cut-and-paste operation along an embedded real projective plane in a 4-manifold is called a Price twist. A Price twist on the 4-sphere produces, up to diffeomorphism, at most three 4-manifolds: the 4-sphere itself, a homotopy 4-sphere, and a non-simply connected closed 4-manifold. In general, the classification of diffeomorphism types of non-simply connected closed 4-manifolds is still far from being well understood. In this talk, we focus on Price twists on the 4-sphere associated with embeddings of the real projective plane of Kinoshita type that yield non-simply connected 4-manifolds. We present several properties of these manifolds and results on the classification of their diffeomorphism types. We also explain pochette surgery, introduced by Zjuñici Iwase and Yukio Matsumoto, which is closely related to the results of this work. This talk is based on joint work with Tsukasa Isoshima (Keio University).
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Operator Algebra Seminars
16:45-18:15 Room #126 (Graduate School of Math. Sci. Bldg.)
Kohki Sakamoto (Univ. Tokyo)
On the spectral gap conjecture for pairs in SU(2)
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Kohki Sakamoto (Univ. Tokyo)
On the spectral gap conjecture for pairs in SU(2)
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
2026/03/27
Colloquium
16:00-17:00 Room #NISSAY Lecture Hall(大講義室) (Graduate School of Math. Sci. Bldg.)
Nakahiro Yoshida (Graduate School of Mathematical Sciences, The University of Tokyo)
A study of chance and randomness: a personal history with selection bias (日本語)
Nakahiro Yoshida (Graduate School of Mathematical Sciences, The University of Tokyo)
A study of chance and randomness: a personal history with selection bias (日本語)
[ Abstract ]
My studies in probability and statistics have been guided by numerous coincidences, even though my direction has at times been seemingly random. Aware of the bias inherent in my selection of topics and retrospective evaluation of events, I reflect on the trajectory that has brought me to the present.
My studies in probability and statistics have been guided by numerous coincidences, even though my direction has at times been seemingly random. Aware of the bias inherent in my selection of topics and retrospective evaluation of events, I reflect on the trajectory that has brought me to the present.
2026/03/19
FJ-LMI Seminar
13:30-14:15 Room #056 (Graduate School of Math. Sci. Bldg.)
Amaury HAYAT (ENPC, Paris)
How can AI Help Mathematicians? (英語)
https://fj-lmi.cnrs.fr/seminars/
Amaury HAYAT (ENPC, Paris)
How can AI Help Mathematicians? (英語)
[ Abstract ]
The advent of artificial intelligence raises an important question: can AI assist mathematicians in solving open problems in mathematics? This talk explores this question from multiple perspectives. We will explore how different types of AI models can be trained to provide valuable insights into mathematical questions from different areas of mathematics and applied mathematics. We will also present recent works on AI models specifically designed for automated theorem proving.
[ Reference URL ]The advent of artificial intelligence raises an important question: can AI assist mathematicians in solving open problems in mathematics? This talk explores this question from multiple perspectives. We will explore how different types of AI models can be trained to provide valuable insights into mathematical questions from different areas of mathematics and applied mathematics. We will also present recent works on AI models specifically designed for automated theorem proving.
https://fj-lmi.cnrs.fr/seminars/
2026/03/18
FJ-LMI Seminar
13:30-14:15 Room #056 (Graduate School of Math. Sci. Bldg.)
Amaury HAYAT (ENPC, Paris)
Stabilization of PDEs and AI for mathematics (英語)
https://fj-lmi.cnrs.fr/seminars/
Amaury HAYAT (ENPC, Paris)
Stabilization of PDEs and AI for mathematics (英語)
[ Abstract ]
Control theory consists in asking: if we can act on a system, what can we make it do? One of the main problems is the stabilization problem: how can we act on a system to guarantee the long-term behavior of its solutions? In this presentation, we will examine this problem from several angles. First, we will look at the problem of stabilizing PDEs from an abstract perspective and present a recent approach called F-equivalence (or sometimes Fredholm backstepping). The principle is simple: instead of trying to find a control that makes the system stable, we look at another problem: we try find a control that renders the PDE system dynamically equivalent to a simpler system for which stability is already known. Besides being interesting in itself, this approach has also resulted in new results in control theory, and we will review the progress that has been made in the last three years. In a second part, we will focus on a more concrete problem: the stabilization of hyperbolic equations modeling road traffic. We will show how abstract mathematical concepts, such as entropic solutions, can have tangible impacts in real-world scenarios, and we will discuss their application to traffic regulation and the reduction of traffic jams.
[ Reference URL ]Control theory consists in asking: if we can act on a system, what can we make it do? One of the main problems is the stabilization problem: how can we act on a system to guarantee the long-term behavior of its solutions? In this presentation, we will examine this problem from several angles. First, we will look at the problem of stabilizing PDEs from an abstract perspective and present a recent approach called F-equivalence (or sometimes Fredholm backstepping). The principle is simple: instead of trying to find a control that makes the system stable, we look at another problem: we try find a control that renders the PDE system dynamically equivalent to a simpler system for which stability is already known. Besides being interesting in itself, this approach has also resulted in new results in control theory, and we will review the progress that has been made in the last three years. In a second part, we will focus on a more concrete problem: the stabilization of hyperbolic equations modeling road traffic. We will show how abstract mathematical concepts, such as entropic solutions, can have tangible impacts in real-world scenarios, and we will discuss their application to traffic regulation and the reduction of traffic jams.
https://fj-lmi.cnrs.fr/seminars/
Applied Analysis
16:00-17:30 Room #128 (Graduate School of Math. Sci. Bldg.)
Dietmar Hoemberg (Weierstrass Institute, Berlin)
A phasefield approach to two-scale topology optimization (English)
Dietmar Hoemberg (Weierstrass Institute, Berlin)
A phasefield approach to two-scale topology optimization (English)
[ Abstract ]
Subject of my presentation is a novel approach for optimizing both the macroscopic shape and the porous mesoscopic structure of components. In the first part of my presentation I will introduce the concept of phasefield based topology optimization. The second part of my presentation is devoted to two-scale topology optimization. The key feature here is the introduction of an additional local volume control (LVC), which allows to adjust the desired spatial scales. The main novelty is that the radius of the LVC may depend both on space and a local stress measure. This allows for creating optimal topologies with heterogeneous mesostructures enforcing any desired spatial grading and accommodating stress concentrations by stress dependent pore size. I will present some analytical results for the resulting optimal control problem and conclude with numerical results showing the versatility of our approach for creating optimal macroscopic designs with tailored mesostructures.
Subject of my presentation is a novel approach for optimizing both the macroscopic shape and the porous mesoscopic structure of components. In the first part of my presentation I will introduce the concept of phasefield based topology optimization. The second part of my presentation is devoted to two-scale topology optimization. The key feature here is the introduction of an additional local volume control (LVC), which allows to adjust the desired spatial scales. The main novelty is that the radius of the LVC may depend both on space and a local stress measure. This allows for creating optimal topologies with heterogeneous mesostructures enforcing any desired spatial grading and accommodating stress concentrations by stress dependent pore size. I will present some analytical results for the resulting optimal control problem and conclude with numerical results showing the versatility of our approach for creating optimal macroscopic designs with tailored mesostructures.
2026/03/11
Number Theory Seminar
17:00-18:00 Room #117 (Graduate School of Math. Sci. Bldg.)
Kam Fai Tam (Xiamen Malaysia University)
A conjectural construction of Arthur Packets in Fargues-Scholze's categorical local Langlands correspondence
Kam Fai Tam (Xiamen Malaysia University)
A conjectural construction of Arthur Packets in Fargues-Scholze's categorical local Langlands correspondence
[ Abstract ]
The presentation consists of two parts. In the first part, we review -- from a novice point of view -- the categorical local Langlands correspondence due to Fargues and Scholze. Topics include: the structure of Bun_G and LocSys_{\hat G}, spectral action via Hecke operators, geometric Satake transform, and some conjectural consequences proposed by Fargues. (Apologies: the p-adic geometry underlying the relative Fargues-Fontaine curve is not included.)
In the second part, I will present a conjectural construction of Arthur packets in Fargues-Scholze's framework. This construction is based on the vanishing cycle functor introduced by Cunningham-Fiori-Moussaoui-Mracek-Xu, which is in turn inspired by Adams-Barbasch-Vogan for real groups. (A confession for curious audiences: this presentation offers essentially no new results. My goal is to illustrate how the legacy of James Arthur may influence other theories.)
The presentation consists of two parts. In the first part, we review -- from a novice point of view -- the categorical local Langlands correspondence due to Fargues and Scholze. Topics include: the structure of Bun_G and LocSys_{\hat G}, spectral action via Hecke operators, geometric Satake transform, and some conjectural consequences proposed by Fargues. (Apologies: the p-adic geometry underlying the relative Fargues-Fontaine curve is not included.)
In the second part, I will present a conjectural construction of Arthur packets in Fargues-Scholze's framework. This construction is based on the vanishing cycle functor introduced by Cunningham-Fiori-Moussaoui-Mracek-Xu, which is in turn inspired by Adams-Barbasch-Vogan for real groups. (A confession for curious audiences: this presentation offers essentially no new results. My goal is to illustrate how the legacy of James Arthur may influence other theories.)
2026/03/10
Operator Algebra Seminars
16:45-18:15 Room #126 (Graduate School of Math. Sci. Bldg.)
Yuki Miyamoto (Chiba University)
Group von Neumann algebras of non-unimodular almost unimodular groups and their twisted versions
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Yuki Miyamoto (Chiba University)
Group von Neumann algebras of non-unimodular almost unimodular groups and their twisted versions
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Operator Algebra Seminars
15:00-16:30 Room #126 (Graduate School of Math. Sci. Bldg.)
Kai Toyosawa (Universität Münster)
Relative biexactness of amalgamated free product von Neumann algebras
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Kai Toyosawa (Universität Münster)
Relative biexactness of amalgamated free product von Neumann algebras
[ Reference URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
2026/03/09
Tokyo-Nagoya Algebra Seminar
16:00-17:30 Online
Kyoungmo Kim 김 경모 (University of Cologne)
Algebras derived equivalent to skew-gentle algebras (English)
https://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
Kyoungmo Kim 김 경모 (University of Cologne)
Algebras derived equivalent to skew-gentle algebras (English)
[ Abstract ]
The class of gentle algebras has several nice properties: its derived categories are well understood, it has deep connections with surface geometry, and it is closed under derived equivalence. A generalized class of skew-gentle algebras also has well-behaved derived categories and a geometric model. However, the class of skew-gentle algebras is not closed under derived equivalence. In this talk, we introduce a larger class of semi-gentle algebras with a geometric model and talk about closedness of the class under derived equivalence. This is a joint work with Severin Barmeier, Cheol-Hyun Cho, Kyungmin Rho, Sibylle Schroll, and Zhengfang Wang.
Zoom ID 834 4165 7899
Password 799113
[ Reference URL ]The class of gentle algebras has several nice properties: its derived categories are well understood, it has deep connections with surface geometry, and it is closed under derived equivalence. A generalized class of skew-gentle algebras also has well-behaved derived categories and a geometric model. However, the class of skew-gentle algebras is not closed under derived equivalence. In this talk, we introduce a larger class of semi-gentle algebras with a geometric model and talk about closedness of the class under derived equivalence. This is a joint work with Severin Barmeier, Cheol-Hyun Cho, Kyungmin Rho, Sibylle Schroll, and Zhengfang Wang.
Zoom ID 834 4165 7899
Password 799113
https://www.math.nagoya-u.ac.jp/~aaron.chan/TNAseminar.html
2026/02/20
Lectures
16:30-17:30 Room #056 (Graduate School of Math. Sci. Bldg.)
Toshiyuki Hibiya (Professor Emeritus, The University of Tokyo)
月と海底地形が織りなす深海乱流の世界 (日本語)
Toshiyuki Hibiya (Professor Emeritus, The University of Tokyo)
月と海底地形が織りなす深海乱流の世界 (日本語)
2026/02/10
Numerical Analysis Seminar
16:30-18:00 Room #122 (Graduate School of Math. Sci. Bldg.)
Franz Chouly (Universidad de la República)
Finite Element Methods for the Elasto-Plastic Torsion Problem (English)
https://sites.google.com/g.ecc.u-tokyo.ac.jp/utnas-bulletin-board/
Franz Chouly (Universidad de la República)
Finite Element Methods for the Elasto-Plastic Torsion Problem (English)
[ Abstract ]
We will describe finite element methods for the elasto-plastic torsion problem, as a prototype of variational inequality with constraints on the gradient of the solution. This problem has been an object of study from the theoretical viewpoint since the 1970s. From the numerical analysis viewpoint, it remains difficult to obtain optimal a priori error estimates. We will present the numerical analysis and numerical results for three methods based on standard Lagrange finite elements of orden 1 or 2: a direct discretization and a Nitsche discretization of a modified variational inequality, when the source term is constant, and a penalty technique for a non constant source term. Particularly the Nitsche technique yields fully optimal a priori error bounds. This is a joint work with Patrick Hild (Université Paul Sabatier, Toulouse, France) and Tom Gustafsson (Aalto University, Finland).
[ Reference URL ]We will describe finite element methods for the elasto-plastic torsion problem, as a prototype of variational inequality with constraints on the gradient of the solution. This problem has been an object of study from the theoretical viewpoint since the 1970s. From the numerical analysis viewpoint, it remains difficult to obtain optimal a priori error estimates. We will present the numerical analysis and numerical results for three methods based on standard Lagrange finite elements of orden 1 or 2: a direct discretization and a Nitsche discretization of a modified variational inequality, when the source term is constant, and a penalty technique for a non constant source term. Particularly the Nitsche technique yields fully optimal a priori error bounds. This is a joint work with Patrick Hild (Université Paul Sabatier, Toulouse, France) and Tom Gustafsson (Aalto University, Finland).
https://sites.google.com/g.ecc.u-tokyo.ac.jp/utnas-bulletin-board/
2026/01/23
thesis presentations
9:15-10:30 Room #118 (Graduate School of Math. Sci. Bldg.)
范 凌虎 (東京大学大学院数理科学研究科)
Modular quotient singularities and their crepant resolutions
（モジュラー商特異点とそのクレパント解消）
范 凌虎 (東京大学大学院数理科学研究科)
Modular quotient singularities and their crepant resolutions
（モジュラー商特異点とそのクレパント解消）
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