本文印刷
全画面プリント
今後の予定
過去の記録 ～09/19｜本日 09/20 | 今後の予定 09/21～
2026年09月28日(月)
東京確率論セミナー
14:00-17:30 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。
Stefan Junk 氏 (Gakushuin University) 14:00-15:15
Some elements of the proof of equivalence of strong and very strong disorder for directed polymers (private seminar)
Dominik Schmid 氏 ( University of Augsburg) 16:00-17:30
The periodic directed landscape
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。
Stefan Junk 氏 (Gakushuin University) 14:00-15:15
Some elements of the proof of equivalence of strong and very strong disorder for directed polymers (private seminar)
Dominik Schmid 氏 ( University of Augsburg) 16:00-17:30
The periodic directed landscape
[ 講演概要 ]
The Kardar--Parisi--Zhang universality class is a central topic in mathematical physics and probability theory. In this talk, we discuss the conjectural scaling limit of periodic models in the Kardar--Parisi--Zhang universality class: the periodic directed landscape. We establish the convergence of periodic exponential last passage percolation to the periodic directed landscape and give a variational characterization of the periodic KPZ fixed point, recently constructed by Baik, Liao, and Liu. We also establish the convergence of periodic asymmetric simple exclusion processes to periodic KPZ fixed points, coupled through the same periodic directed landscape. A key ingredient is a gluing technique for combining overlapping directed landscapes, which may be of independent interest. This is based on joint work with Amol Aggarwal and Ivan Corwin.
The Kardar--Parisi--Zhang universality class is a central topic in mathematical physics and probability theory. In this talk, we discuss the conjectural scaling limit of periodic models in the Kardar--Parisi--Zhang universality class: the periodic directed landscape. We establish the convergence of periodic exponential last passage percolation to the periodic directed landscape and give a variational characterization of the periodic KPZ fixed point, recently constructed by Baik, Liao, and Liu. We also establish the convergence of periodic asymmetric simple exclusion processes to periodic KPZ fixed points, coupled through the same periodic directed landscape. A key ingredient is a gluing technique for combining overlapping directed landscapes, which may be of independent interest. This is based on joint work with Amol Aggarwal and Ivan Corwin.
2026年10月02日(金)
代数幾何学セミナー
10:30-12:00 数理科学研究科棟(駒場) 122号室
いつもと時間帯・部屋が異なります。
JongHae Keum 氏 (KIAS)
Automorphisms of Fermat quartic surface
いつもと時間帯・部屋が異なります。
JongHae Keum 氏 (KIAS)
Automorphisms of Fermat quartic surface
[ 講演概要 ]
In 1944 Beniamino Segre proved that the Fermat quartic surface in the 3-dimensional projective space has infinitely many discrete automorphisms. It was the first example of an algebraic surface with infinite discrete automorphism group. Since then, it has long been an open problem to find generators of its automorphism group.
On the other hand, any other Fermat hypersurface of dimension > 1 and degree > 2 admits only projectively linear automorphisms, and has finite automorphism group.
With Keiji Oguiso and Xun Yu, we solve this problem, finding 16 geometric generators of finite order.
I will present this result, along with history of computation of automorphism groups of other K3 surfaces.
In 1944 Beniamino Segre proved that the Fermat quartic surface in the 3-dimensional projective space has infinitely many discrete automorphisms. It was the first example of an algebraic surface with infinite discrete automorphism group. Since then, it has long been an open problem to find generators of its automorphism group.
On the other hand, any other Fermat hypersurface of dimension > 1 and degree > 2 admits only projectively linear automorphisms, and has finite automorphism group.
With Keiji Oguiso and Xun Yu, we solve this problem, finding 16 geometric generators of finite order.
I will present this result, along with history of computation of automorphism groups of other K3 surfaces.
2026年10月05日(月)
作用素環セミナー
15:30-17:00 数理科学研究科棟(駒場) 126号室
森 孟彦 氏 (サレジオ工業高専)
The qx+r problem and the Cuntz algebra
森 孟彦 氏 (サレジオ工業高専)
The qx+r problem and the Cuntz algebra
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
久本 智之 氏 (名古屋大学)
Miyaoka–Yau inequality, delta invariant, and the Calabi functional (Japanese)
https://forms.gle/8ERsVDLuKHwbVzm57
久本 智之 氏 (名古屋大学)
Miyaoka–Yau inequality, delta invariant, and the Calabi functional (Japanese)
[ 講演概要 ]
本講演は、岩井雅崇氏（大阪大学）との共同研究に基づく。我々は（K安定とは限らない）一般のFano多様体に対して、いわゆるδ不変量を組み込む形で宮岡-Yau型の不等式を確立した。この新しい不等式の等号成立条件、そしてCalabi汎関数との関係について紹介したい。
[ 参考URL ]本講演は、岩井雅崇氏（大阪大学）との共同研究に基づく。我々は（K安定とは限らない）一般のFano多様体に対して、いわゆるδ不変量を組み込む形で宮岡-Yau型の不等式を確立した。この新しい不等式の等号成立条件、そしてCalabi汎関数との関係について紹介したい。
https://forms.gle/8ERsVDLuKHwbVzm57
東京確率論セミナー
16:50-18:20 数理科学研究科棟(駒場) 122号室
教室は１２２です。今日はTea Time はありません。
田口 大 氏 (関西大学)
Euler–Maruyama scheme with unbounded Hölder drift
教室は１２２です。今日はTea Time はありません。
田口 大 氏 (関西大学)
Euler–Maruyama scheme with unbounded Hölder drift
[ 講演概要 ]
In this talk, we establish the strong rate of convergence of the Euler--Maruyama scheme for multidimensional stochastic differential equations with unbounded, uniformly locally Hölder continuous drift and multiplicative noise. Our approach relies on the Itô--Tanaka trick (Zvonkin-type transformation) adapted to unbounded drift. Furthermore, in order to apply the stochastic sewing lemma, we employ heat kernel estimates for the transition density of the Euler--Maruyama scheme. This talk is based on joint work with Tsukasa Moritoki (Okayama university).
In this talk, we establish the strong rate of convergence of the Euler--Maruyama scheme for multidimensional stochastic differential equations with unbounded, uniformly locally Hölder continuous drift and multiplicative noise. Our approach relies on the Itô--Tanaka trick (Zvonkin-type transformation) adapted to unbounded drift. Furthermore, in order to apply the stochastic sewing lemma, we employ heat kernel estimates for the transition density of the Euler--Maruyama scheme. This talk is based on joint work with Tsukasa Moritoki (Okayama university).
2026年10月06日(火)
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
Yohance Osborne 氏 (Durham University)
Numerical approximation of mean field games systems (English)
https://sites.google.com/g.ecc.u-tokyo.ac.jp/utnas-bulletin-board/
Yohance Osborne 氏 (Durham University)
Numerical approximation of mean field games systems (English)
[ 講演概要 ]
Mean field games (MFG) are models for Nash equilibria of competitive differential games of optimal control involving a continuum of players. MFG equilibria are often described by systems of partial differential equations, where a Hamilton–Jacobi–Bellman (HJB) equation for the representative player’s value function is coupled nonlinearly with a Kolmogorov–Fokker–Planck (KFP) equation that determines the player distribution. MFG systems are particularly challenging to approximate computationally because they exhibit the following difficulties all at once: nonlinear couplings between the HJB and KFP equations, a temporal forward–backward structure, non-negativity of absolutely continuous player distributions, as well as potential nondifferentiability of the Hamiltonian. This talk addresses the numerical approximation of MFG systems for two classes of numerical schemes: (1) monotone stabilized finite element methods for second-order MFG systems with nondifferentiable Hamiltonians, and (2) particle methods for first-order MFG systems under displacement monotonicity. I will present theorems on the strong convergence of these numerical schemes and their rates of convergence, along with discussion of some numerical experiments.
[ 参考URL ]Mean field games (MFG) are models for Nash equilibria of competitive differential games of optimal control involving a continuum of players. MFG equilibria are often described by systems of partial differential equations, where a Hamilton–Jacobi–Bellman (HJB) equation for the representative player’s value function is coupled nonlinearly with a Kolmogorov–Fokker–Planck (KFP) equation that determines the player distribution. MFG systems are particularly challenging to approximate computationally because they exhibit the following difficulties all at once: nonlinear couplings between the HJB and KFP equations, a temporal forward–backward structure, non-negativity of absolutely continuous player distributions, as well as potential nondifferentiability of the Hamiltonian. This talk addresses the numerical approximation of MFG systems for two classes of numerical schemes: (1) monotone stabilized finite element methods for second-order MFG systems with nondifferentiable Hamiltonians, and (2) particle methods for first-order MFG systems under displacement monotonicity. I will present theorems on the strong convergence of these numerical schemes and their rates of convergence, along with discussion of some numerical experiments.
https://sites.google.com/g.ecc.u-tokyo.ac.jp/utnas-bulletin-board/
2026年10月08日(木)
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
木曜日の開催になります。ご注意ください。
Marcus Grote 氏 (University of Basel)
Adaptive FEM with Explicit Time Integration For the Wave Equation
(English)
https://sites.google.com/g.ecc.u-tokyo.ac.jp/utnas-bulletin-board/
木曜日の開催になります。ご注意ください。
Marcus Grote 氏 (University of Basel)
Adaptive FEM with Explicit Time Integration For the Wave Equation
(English)
[ 講演概要 ]
Starting from a recent a posteriori error estimator for the finite element solution of the wave equation with explicit time integration [Grote, Lakkis, Santos, 2024], we devise a space-time adaptive strategy which includes both time evolving meshes and local time-stepping to overcome any overly stringent CFL stability restriction on the time-step due to local mesh refinement. Moreover, at each time-step the adaptive algorithm monitors the accuracy thanks to the error indicators and recomputes the current step on a refined mesh until the desired tolerance is met; meanwhile, the mesh is coarsened in regions of smaller errors. Leapfrog based local time-stepping is applied in all regions of local mesh refinement to incorporate adaptivity into fully explicit time integration with mesh change while retaining efficiency. Numerical results illustrate the optimal rate of convergence of the a posteriori error estimators on time evolving meshes.
[ 参考URL ]Starting from a recent a posteriori error estimator for the finite element solution of the wave equation with explicit time integration [Grote, Lakkis, Santos, 2024], we devise a space-time adaptive strategy which includes both time evolving meshes and local time-stepping to overcome any overly stringent CFL stability restriction on the time-step due to local mesh refinement. Moreover, at each time-step the adaptive algorithm monitors the accuracy thanks to the error indicators and recomputes the current step on a refined mesh until the desired tolerance is met; meanwhile, the mesh is coarsened in regions of smaller errors. Leapfrog based local time-stepping is applied in all regions of local mesh refinement to incorporate adaptivity into fully explicit time integration with mesh change while retaining efficiency. Numerical results illustrate the optimal rate of convergence of the a posteriori error estimators on time evolving meshes.
https://sites.google.com/g.ecc.u-tokyo.ac.jp/utnas-bulletin-board/
2026年10月19日(月)
作用素環セミナー
15:30-17:00 数理科学研究科棟(駒場) 126号室
Xin-Hai Tong 氏 (東京大学)
Clustering Theorem for Bose--Hubbard class Gibbs states
Xin-Hai Tong 氏 (東京大学)
Clustering Theorem for Bose--Hubbard class Gibbs states
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
幸谷 亮汰 氏 (東京科学大学)
TBA (Japanese)
[ 参考URL ]
https://forms.gle/8ERsVDLuKHwbVzm57
幸谷 亮汰 氏 (東京科学大学)
TBA (Japanese)
[ 参考URL ]
https://forms.gle/8ERsVDLuKHwbVzm57
2026年10月26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
小池 貴之 氏 (筑波大学)
TBA (Japanese)
[ 参考URL ]
https://forms.gle/8ERsVDLuKHwbVzm57
小池 貴之 氏 (筑波大学)
TBA (Japanese)
[ 参考URL ]
https://forms.gle/8ERsVDLuKHwbVzm57
作用素環セミナー
15:30-17:00 数理科学研究科棟(駒場) 126号室
向原 未帆 氏 (九州大学)
TBA
向原 未帆 氏 (九州大学)
TBA
2026年11月02日(月)
作用素環セミナー
15:30-17:00 数理科学研究科棟(駒場) 126号室
森 迪也 氏 (新潟大学)
TBA
森 迪也 氏 (新潟大学)
TBA
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
高倉 真和 氏 (東京都立大学)
TBA (Japanese)
https://forms.gle/8ERsVDLuKHwbVzm57
高倉 真和 氏 (東京都立大学)
TBA (Japanese)
[ 講演概要 ]
TBA
[ 参考URL ]TBA
https://forms.gle/8ERsVDLuKHwbVzm57
2026年11月09日(月)
作用素環セミナー
15:30-17:00 数理科学研究科棟(駒場) 126号室
關山 輝流 氏 (慶應義塾大学)
KS-Groupoids and KS-Crossed Products associated with Inverse Semigroup Actions
關山 輝流 氏 (慶應義塾大学)
KS-Groupoids and KS-Crossed Products associated with Inverse Semigroup Actions
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
野口 潤次郎 氏 (東京大学)
多変数複素解析入門講義法 II：解析的多面体と岡シジジー (Japanese)
https://forms.gle/8ERsVDLuKHwbVzm57
野口 潤次郎 氏 (東京大学)
多変数複素解析入門講義法 II：解析的多面体と岡シジジー (Japanese)
[ 講演概要 ]
連接層の岡シジジーは岡理論における重要ポイントで、岡・カルタン理論もここまでは共通である。その結果をそのまま使うと岡理論、コホモロジー理論につなげると岡・カルタン理論となる。
通常、岡シジジーを閉直方体上で示したあと、解析的多面体上で形式化する。その解析的多面体も、開、閉の二つの流儀が歴史的にある。いずれにしても、その定義には微妙な点があり、入門講義で扱うときには注意が要る。ここでは、それらを少し論じた後に岡シジジーを正則凸集合上で定式化すると労は同じであるが扱い易くなり、記述もスッキリすることを例を通じて見たい。
[ 参考URL ]連接層の岡シジジーは岡理論における重要ポイントで、岡・カルタン理論もここまでは共通である。その結果をそのまま使うと岡理論、コホモロジー理論につなげると岡・カルタン理論となる。
通常、岡シジジーを閉直方体上で示したあと、解析的多面体上で形式化する。その解析的多面体も、開、閉の二つの流儀が歴史的にある。いずれにしても、その定義には微妙な点があり、入門講義で扱うときには注意が要る。ここでは、それらを少し論じた後に岡シジジーを正則凸集合上で定式化すると労は同じであるが扱い易くなり、記述もスッキリすることを例を通じて見たい。
https://forms.gle/8ERsVDLuKHwbVzm57
2026年11月16日(月)
作用素環セミナー
15:30-17:00 数理科学研究科棟(駒場) 126号室
阪本 皓貴 氏 (東大数理)
TBA
阪本 皓貴 氏 (東大数理)
TBA
2026年11月30日(月)
作用素環セミナー
15:30-17:00 数理科学研究科棟(駒場) 126 号室
紅村 冬大 氏 (九州工業大学)
Cartan-preserving *-automorphism groups: realization and obstructions for compact abelian groups
紅村 冬大 氏 (九州工業大学)
Cartan-preserving *-automorphism groups: realization and obstructions for compact abelian groups
[ 講演概要 ]
In this talk, we investigate automorphism groups preserving Cartan subalgebras of C*-algebras. First, we describe these groups in terms of automorphisms and 1-cocycles of twisted étale groupoids. As a consequence, we obtain a C*-algebraic analogue of a theorem of Feldman and Moore on Cartan-preserving automorphisms of von Neumann algebras. We then study Cartan-fixing automorphism groups. We show that every UCT Kirchberg algebra admits a Cartan subalgebra whose Cartan-fixing automorphism group contains every second countable compact abelian group. In contrast, for C*-algebras arising from expansive effective groupoids, we prove that compact Cartan-fixing automorphism groups must have finitely generated Pontryagin duals if the fixed point subalgebras are prime. As an application, we establish the existence of inequivalent Cartan subalgebras for Kirchberg algebras arising from expansive effective groupoids.
In this talk, we investigate automorphism groups preserving Cartan subalgebras of C*-algebras. First, we describe these groups in terms of automorphisms and 1-cocycles of twisted étale groupoids. As a consequence, we obtain a C*-algebraic analogue of a theorem of Feldman and Moore on Cartan-preserving automorphisms of von Neumann algebras. We then study Cartan-fixing automorphism groups. We show that every UCT Kirchberg algebra admits a Cartan subalgebra whose Cartan-fixing automorphism group contains every second countable compact abelian group. In contrast, for C*-algebras arising from expansive effective groupoids, we prove that compact Cartan-fixing automorphism groups must have finitely generated Pontryagin duals if the fixed point subalgebras are prime. As an application, we establish the existence of inequivalent Cartan subalgebras for Kirchberg algebras arising from expansive effective groupoids.
2026年12月07日(月)
作用素環セミナー
15:30-17:00 数理科学研究科棟(駒場) 126号室
宮川 明裕 氏 (京都大学)
TBA
宮川 明裕 氏 (京都大学)
TBA
2027年01月18日(月)
作用素環セミナー
15:30-17:00 数理科学研究科棟(駒場) 126号室
藤江 克徳 氏 (愛知県立大学)
TBA
藤江 克徳 氏 (愛知県立大学)
TBA
