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過去の記録 ～06/22｜本日 06/23 | 今後の予定 06/24～
2025年06月24日(火)
作用素環セミナー
16:45-18:15 数理科学研究科棟(駒場) 117号室
George Elliott 氏 (Univ. Toronto)
Recent progress in the classification of C∗-algebras
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
George Elliott 氏 (Univ. Toronto)
Recent progress in the classification of C∗-algebras
[ 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
17:00-18:30 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。
Danny Calegari 氏 (The University of Chicago)
Universal circles and Zippers (1) (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。
Danny Calegari 氏 (The University of Chicago)
Universal circles and Zippers (1) (ENGLISH)
[ 講演概要 ]
If M is a hyperbolic 3-manifold fibering over the circle, then the fundamental group of M acts faithfully by homeomorphisms on a circle—the circle at infinity of the universal cover of the fiber—preserving a pair of invariant (stable and unstable) laminations. Many different kinds of dynamical structures including taut foliations and quasigeodesic or pseudo-Anosov flows are known to give rise to universal circles—a circle with a faithful action of the fundamental group preserving a pair of invariant laminations—and those universal circles play a key role in relating the dynamical structure to the geometry of M. In these two talks, I will introduce the idea of *zippers*, which give a new and direct way to construct universal circles, streamlining the known constructions in many cases, and giving a host of new constructions in others. In particular, zippers—and their associated universal circles—may be constructed directly from homological objects (uniform quasimorphisms), causal structures (uniform left orders), and many other structures. This is joint work with Ino Loukidou.
[ 参考URL ]If M is a hyperbolic 3-manifold fibering over the circle, then the fundamental group of M acts faithfully by homeomorphisms on a circle—the circle at infinity of the universal cover of the fiber—preserving a pair of invariant (stable and unstable) laminations. Many different kinds of dynamical structures including taut foliations and quasigeodesic or pseudo-Anosov flows are known to give rise to universal circles—a circle with a faithful action of the fundamental group preserving a pair of invariant laminations—and those universal circles play a key role in relating the dynamical structure to the geometry of M. In these two talks, I will introduce the idea of *zippers*, which give a new and direct way to construct universal circles, streamlining the known constructions in many cases, and giving a host of new constructions in others. In particular, zippers—and their associated universal circles—may be constructed directly from homological objects (uniform quasimorphisms), causal structures (uniform left orders), and many other structures. This is joint work with Ino Loukidou.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
2025年06月26日(木)
応用解析セミナー
16:00-17:30 数理科学研究科棟(駒場) 128号室
Yang Yang 氏 (Johns Hopkins University)
A half-space Bernstein theorem for anisotropic minimal graphs (English)
Yang Yang 氏 (Johns Hopkins University)
A half-space Bernstein theorem for anisotropic minimal graphs (English)
[ 講演概要 ]
Anisotropic functionals are the natural generalization of the area functional. From a technical perspective, what distinguishes general anisotropic functionals from the area case is the absence of a monotonicity formula. In this talk, we will present a proof of a half-space Bernstein theorem for anisotropic minimal graphs with flat boundary condition. The proof uses only the maximal principle and ideas from fully nonlinear PDE theory in lieu of a monotonicity formula. This is joint work with W. Du, C. Moony, and J. Zhu.
Anisotropic functionals are the natural generalization of the area functional. From a technical perspective, what distinguishes general anisotropic functionals from the area case is the absence of a monotonicity formula. In this talk, we will present a proof of a half-space Bernstein theorem for anisotropic minimal graphs with flat boundary condition. The proof uses only the maximal principle and ideas from fully nonlinear PDE theory in lieu of a monotonicity formula. This is joint work with W. Du, C. Moony, and J. Zhu.
トポロジー火曜セミナー
15:30-17:00 数理科学研究科棟(駒場) hybrid/122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。
Danny Calegari 氏 (The University of Chicago)
Universal circles and Zippers (2) (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。
Danny Calegari 氏 (The University of Chicago)
Universal circles and Zippers (2) (ENGLISH)
[ 講演概要 ]
If M is a hyperbolic 3-manifold fibering over the circle, then the fundamental group of M acts faithfully by homeomorphisms on a circle—the circle at infinity of the universal cover of the fiber—preserving a pair of invariant (stable and unstable) laminations. Many different kinds of dynamical structures including taut foliations and quasigeodesic or pseudo-Anosov flows are known to give rise to universal circles—a circle with a faithful action of the fundamental group preserving a pair of invariant laminations—and those universal circles play a key role in relating the dynamical structure to the geometry of M. In these two talks, I will introduce the idea of *zippers*, which give a new and direct way to construct universal circles, streamlining the known constructions in many cases, and giving a host of new constructions in others. In particular, zippers—and their associated universal circles—may be constructed directly from homological objects (uniform quasimorphisms), causal structures (uniform left orders), and many other structures. This is joint work with Ino Loukidou.
[ 参考URL ]If M is a hyperbolic 3-manifold fibering over the circle, then the fundamental group of M acts faithfully by homeomorphisms on a circle—the circle at infinity of the universal cover of the fiber—preserving a pair of invariant (stable and unstable) laminations. Many different kinds of dynamical structures including taut foliations and quasigeodesic or pseudo-Anosov flows are known to give rise to universal circles—a circle with a faithful action of the fundamental group preserving a pair of invariant laminations—and those universal circles play a key role in relating the dynamical structure to the geometry of M. In these two talks, I will introduce the idea of *zippers*, which give a new and direct way to construct universal circles, streamlining the known constructions in many cases, and giving a host of new constructions in others. In particular, zippers—and their associated universal circles—may be constructed directly from homological objects (uniform quasimorphisms), causal structures (uniform left orders), and many other structures. This is joint work with Ino Loukidou.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
2025年06月27日(金)
東京無限可積分系セミナー
14:00-16:00 数理科学研究科棟(駒場) 056号室
Boris Feigin 氏 (Hebrew University)
W-algebra for supergroups, cosets and Langlands-type duality for supergroups
(English)
Boris Feigin 氏 (Hebrew University)
W-algebra for supergroups, cosets and Langlands-type duality for supergroups
(English)
[ 講演概要 ]
I try to explain what is known about the Langlands duality for superalgebras and also say something about center on a critical level for superalgebras.
I try to explain what is known about the Langlands duality for superalgebras and also say something about center on a critical level for superalgebras.
2025年07月01日(火)
作用素環セミナー
16:45-18:15 数理科学研究科棟(駒場) 117号室
星野真生 氏 (東大数理)
A tensor categorical aspect of quantum group actions
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
星野真生 氏 (東大数理)
A tensor categorical aspect of quantum group actions
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
2025年07月03日(木)
応用解析セミナー
16:00-17:30 数理科学研究科棟(駒場) 128号室
確率論セミナーと合同開催
Jessica Lin 氏 (McGill University)
Generalized Front Propagation for Stochastic Spatial Models (English)
確率論セミナーと合同開催
Jessica Lin 氏 (McGill University)
Generalized Front Propagation for Stochastic Spatial Models (English)
[ 講演概要 ]
In this talk, I will present a general framework which can be used to analyze the scaling limits of various stochastic spatial "population" models. Such models include ternary Branching Brownian motion subject to majority voting and several interacting particle systems motivated by biology. The approach is based on moment duality and a PDE methodology introduced by Barles and Souganidis, which can be used to study the asymptotic behaviour of rescaled reaction-diffusion equations. In the limit, the models exhibit phase separation with an evolving interface which is governed by a global-in-time, generalized notion of mean-curvature flow. This talk is based on joint work with Thomas Hughes (University of Bath).
In this talk, I will present a general framework which can be used to analyze the scaling limits of various stochastic spatial "population" models. Such models include ternary Branching Brownian motion subject to majority voting and several interacting particle systems motivated by biology. The approach is based on moment duality and a PDE methodology introduced by Barles and Souganidis, which can be used to study the asymptotic behaviour of rescaled reaction-diffusion equations. In the limit, the models exhibit phase separation with an evolving interface which is governed by a global-in-time, generalized notion of mean-curvature flow. This talk is based on joint work with Thomas Hughes (University of Bath).
東京確率論セミナー
16:00-17:30 数理科学研究科棟(駒場) 128号室
教室は１２8です。応用解析セミナーとの合同セミナーです。 今日はTea Time はありません。
Jessica Lin 氏 (McGill University)
Generalized Front Propagation for Stochastic Spatial Models
教室は１２8です。応用解析セミナーとの合同セミナーです。 今日はTea Time はありません。
Jessica Lin 氏 (McGill University)
Generalized Front Propagation for Stochastic Spatial Models
[ 講演概要 ]
In this talk, I will present a general framework which can be used to analyze the scaling limits of various stochastic spatial "population" models. Such models include ternary Branching Brownian motion subject to majority voting and several interacting particle systems motivated by biology. The approach is based on moment duality and a PDE methodology introduced by Barles and Souganidis, which can be used to study the asymptotic behaviour of rescaled reaction-diffusion equations. In the limit, the models exhibit phase separation with an evolving interface which is governed by a global-in-time, generalized notion of mean-curvature flow. This talk is based on joint work with Thomas Hughes (University of Bath).
In this talk, I will present a general framework which can be used to analyze the scaling limits of various stochastic spatial "population" models. Such models include ternary Branching Brownian motion subject to majority voting and several interacting particle systems motivated by biology. The approach is based on moment duality and a PDE methodology introduced by Barles and Souganidis, which can be used to study the asymptotic behaviour of rescaled reaction-diffusion equations. In the limit, the models exhibit phase separation with an evolving interface which is governed by a global-in-time, generalized notion of mean-curvature flow. This talk is based on joint work with Thomas Hughes (University of Bath).
2025年07月07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) 128号室
丸亀 泰二 氏 (電気通信大学)
Chains on twistor CR manifolds and conformal geodesics in dimension three (Japanese)
https://forms.gle/gTP8qNZwPyQyxjTj8
丸亀 泰二 氏 (電気通信大学)
Chains on twistor CR manifolds and conformal geodesics in dimension three (Japanese)
[ 講演概要 ]
任意の3次元共形多様体(Σ,[g])には，ツイスターCR多様体と呼ばれる5次元Lorentz CR多様体が付随する．Mは，Σ上の計量gを固定すると，(Σ,g)の単位接球面束と同一視できる．この講演では，Mに対するFefferman計量(CR多様体のS1束上に自然に定まる共形計量)を，(Σ,g)のフレーム束上に具体的に構成し，M上の自然な曲線族であるchainの射影が，Σ上の共形測地線となることを説明する．応用として，3次元共形多様体の共形測地線が，全捩率汎関数の臨界曲線として特徴づけられることを述べる．
[ 参考URL ]任意の3次元共形多様体(Σ,[g])には，ツイスターCR多様体と呼ばれる5次元Lorentz CR多様体が付随する．Mは，Σ上の計量gを固定すると，(Σ,g)の単位接球面束と同一視できる．この講演では，Mに対するFefferman計量(CR多様体のS1束上に自然に定まる共形計量)を，(Σ,g)のフレーム束上に具体的に構成し，M上の自然な曲線族であるchainの射影が，Σ上の共形測地線となることを説明する．応用として，3次元共形多様体の共形測地線が，全捩率汎関数の臨界曲線として特徴づけられることを述べる．
https://forms.gle/gTP8qNZwPyQyxjTj8
2025年07月08日(火)
数値解析セミナー
16:30-18:00 数理科学研究科棟(駒場) 126号室
今川真城 氏 (京都大学大学院情報学研究科)
Convergence analysis of perturbed advection equations in a bounded domain (Japanese)
https://sites.google.com/g.ecc.u-tokyo.ac.jp/utnas-bulletin-board/
今川真城 氏 (京都大学大学院情報学研究科)
Convergence analysis of perturbed advection equations in a bounded domain (Japanese)
[ 講演概要 ]
移流方程式は流体のみならず広範な輸送現象を記述する1階偏微分方程式であり，その数学解析においては，2階の楕円型作用素に微小パラメータを乗じた項を付加して得られる近似方程式がしばしば考察される．この摂動項は数値計算において安定化効果に寄与する一方で，これは方程式の階数を変化させる特異摂動であるため，特に有界領域における境界値問題を扱う際には注意を要する．本講演では線型移流方程式の境界値問題に話題を限定し，近似方程式に課す境界条件が近似解の収束率に与える影響について議論する．また，得られた収束評価の妥当性を検証するための数値計算例も紹介する．
本講演は川越大輔先生（京都大学）との共同研究に基づく．
参考文献：
M. Imagawa and D. Kawagoe, On strong convergence of an elliptic regularization with the Neumann boundary condition applied to a stationary advection equation. arXiv:2303.17904
[ 参考URL ]移流方程式は流体のみならず広範な輸送現象を記述する1階偏微分方程式であり，その数学解析においては，2階の楕円型作用素に微小パラメータを乗じた項を付加して得られる近似方程式がしばしば考察される．この摂動項は数値計算において安定化効果に寄与する一方で，これは方程式の階数を変化させる特異摂動であるため，特に有界領域における境界値問題を扱う際には注意を要する．本講演では線型移流方程式の境界値問題に話題を限定し，近似方程式に課す境界条件が近似解の収束率に与える影響について議論する．また，得られた収束評価の妥当性を検証するための数値計算例も紹介する．
本講演は川越大輔先生（京都大学）との共同研究に基づく．
参考文献：
M. Imagawa and D. Kawagoe, On strong convergence of an elliptic regularization with the Neumann boundary condition applied to a stationary advection equation. arXiv:2303.17904
https://sites.google.com/g.ecc.u-tokyo.ac.jp/utnas-bulletin-board/
解析学火曜セミナー
16:00-17:30 数理科学研究科棟(駒場) 002号室
髙棹圭介 氏 (京都大学)
Brakke's inequality and the existence of Brakke flow for volume preserving mean curvature flow (Japanese)
髙棹圭介 氏 (京都大学)
Brakke's inequality and the existence of Brakke flow for volume preserving mean curvature flow (Japanese)
[ 講演概要 ]
We consider the existence of the weak solutions to the volume preserving mean curvature flow. The Brakke flow defined using Brakke's inequality is well known as one of the weak solutions to the mean curvature flow. On the other hand, the volume preserving mean curvature flow has been studied via L2-flow solution, BV solution, and flat flow, but the corresponding Brakke flow had not been considered so far. In this talk, we define the suitable Brakke flow for the volume preserving flow and show its global existence. This talk is based on joint works with Andrea Chiesa (University of Vienna).
We consider the existence of the weak solutions to the volume preserving mean curvature flow. The Brakke flow defined using Brakke's inequality is well known as one of the weak solutions to the mean curvature flow. On the other hand, the volume preserving mean curvature flow has been studied via L2-flow solution, BV solution, and flat flow, but the corresponding Brakke flow had not been considered so far. In this talk, we define the suitable Brakke flow for the volume preserving flow and show its global existence. This talk is based on joint works with Andrea Chiesa (University of Vienna).
2025年07月10日(木)
幾何解析セミナー
14:00-15:00 数理科学研究科棟(駒場) 056号室
Jeff Viaclovsky 氏 (University of California, Irvine)
TBA (英語)
Jeff Viaclovsky 氏 (University of California, Irvine)
TBA (英語)
[ 講演概要 ]
TBA
TBA
2025年07月22日(火)
作用素環セミナー
16:45-18:15 数理科学研究科棟(駒場) 117号室
Giovanni Ferrer 氏 (Ohio State University)
Higher quantum symmetries
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
Giovanni Ferrer 氏 (Ohio State University)
Higher quantum symmetries
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/~yasuyuki/tokyo-seminar.htm
2025年07月29日(火)
数値解析セミナー
16:30-18:00 数理科学研究科棟(駒場) 123号室
鈴木貴 氏 (大阪大学)
有界領域上のHodge分解の解析的証明とその応用 (Japanese)
鈴木貴 氏 (大阪大学)
有界領域上のHodge分解の解析的証明とその応用 (Japanese)
[ 講演概要 ]
有界領域上での微分形式についてそのHodge分解の解析的証明を与えていくつかの応用を紹介する。これは3次元のベクトル場に関する最近の結果の自然な拡張になっている。境界のある多様体の場合やBrezzi-Kikuchi不等式との関連性を述べ、Helmholtz分解の数値解法について新しいスキームを提案する。
有界領域上での微分形式についてそのHodge分解の解析的証明を与えていくつかの応用を紹介する。これは3次元のベクトル場に関する最近の結果の自然な拡張になっている。境界のある多様体の場合やBrezzi-Kikuchi不等式との関連性を述べ、Helmholtz分解の数値解法について新しいスキームを提案する。
2025年09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
Kang Li 氏 (FAU Erlangen-Nürnberg)
Dimension theories from groupoids to classifiable C∗-algebras, and back again
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/seminar/operalge/future.html
Kang Li 氏 (FAU Erlangen-Nürnberg)
Dimension theories from groupoids to classifiable C∗-algebras, and back again
[ 参考URL ]
https://www.ms.u-tokyo.ac.jp/seminar/operalge/future.html
