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Seminar information archive
Seminar information archive ～04/01｜Today's seminar 04/02 | Future seminars 04/03～
Tokyo Probability Seminar
17:00-18:30 Room #126 (Graduate School of Math. Sci. Bldg.)
Sunder Sethuraman (University of Arizona)
Atypical behaviors of a tagged particle in asymmetric simple exclusion (English)
Sunder Sethuraman (University of Arizona)
Atypical behaviors of a tagged particle in asymmetric simple exclusion (English)
[ Abstract ]
Informally, the one dimensional asymmetric simple exclusion process follows a collection of continuous time random walks on Z interacting as follows: When a clock rings, the particle jumps to the nearest right or left with probabilities p or q=1-p, if that location is unoccupied. If occupied, the jump is suppressed and clocks start again.
In this system, seen as a toy model of `traffic', the motion of a distinguished or `tagged' particle is of interest. Starting from a stationary state, we study the `typical' behavior of a tagged particle, conditioned to deviate to an `atypical' position at time Nt, for a t>0 fixed. In the course of results, an `upper tail' large deviation principle, in scale N, is established for the position of the tagged particle. Also, with respect to `lower tail' events, in the totally asymmetric version, a connection is made with a `nonentropy' solution of the associated hydrodynamic Burgers equation. This is work with S.R.S. Varadhan (arXiv:2311.0780).
Informally, the one dimensional asymmetric simple exclusion process follows a collection of continuous time random walks on Z interacting as follows: When a clock rings, the particle jumps to the nearest right or left with probabilities p or q=1-p, if that location is unoccupied. If occupied, the jump is suppressed and clocks start again.
In this system, seen as a toy model of `traffic', the motion of a distinguished or `tagged' particle is of interest. Starting from a stationary state, we study the `typical' behavior of a tagged particle, conditioned to deviate to an `atypical' position at time Nt, for a t>0 fixed. In the course of results, an `upper tail' large deviation principle, in scale N, is established for the position of the tagged particle. Also, with respect to `lower tail' events, in the totally asymmetric version, a connection is made with a `nonentropy' solution of the associated hydrodynamic Burgers equation. This is work with S.R.S. Varadhan (arXiv:2311.0780).
2024/01/30
FJ-LMI Seminar
16:30-17:30 Room # (Graduate School of Math. Sci. Bldg.)
Danielle HILHORST (CNRS, Université de Paris-Saclay, France)
Convergence of solutions of a one-phase Stefan problem with Neumann boundary data to a self-similar profile (英語)
https://fj-lmi.cnrs.fr/seminars/
Danielle HILHORST (CNRS, Université de Paris-Saclay, France)
Convergence of solutions of a one-phase Stefan problem with Neumann boundary data to a self-similar profile (英語)
[ Abstract ]
We study a one-dimensional one-phase Stefan problem with a Neumann boundary condition on the fixed part of the boundary.
We construct a unique self-similar solution and show that for a large class of initial data, the solution of the time evolution problem
converges to this self-similar solution as time tends to infinity. Similar results were already obtained by Bouguezzi, Hilhorst,
Miyamoto, and Scheid in the case of Dirichlet data on the fixed boundary. However, they had to show that the space derivative
of the solution uniformly converges to its limit. Here, our proof requires less regularity, which should make our arguments easier
to adapt to different settings.
This is a joint work with Sabrina Roscani and Piotr Rybka.
[ Reference URL ]We study a one-dimensional one-phase Stefan problem with a Neumann boundary condition on the fixed part of the boundary.
We construct a unique self-similar solution and show that for a large class of initial data, the solution of the time evolution problem
converges to this self-similar solution as time tends to infinity. Similar results were already obtained by Bouguezzi, Hilhorst,
Miyamoto, and Scheid in the case of Dirichlet data on the fixed boundary. However, they had to show that the space derivative
of the solution uniformly converges to its limit. Here, our proof requires less regularity, which should make our arguments easier
to adapt to different settings.
This is a joint work with Sabrina Roscani and Piotr Rybka.
https://fj-lmi.cnrs.fr/seminars/
Applied Analysis
16:30-17:30 Room #002 (Graduate School of Math. Sci. Bldg.)
Danielle Hilhorst (CNRS / Université de Paris-Saclay)
Convergence of solutions of a one-phase Stefan problem with Neumann boundary data to a self-similar profile. (English)
Danielle Hilhorst (CNRS / Université de Paris-Saclay)
Convergence of solutions of a one-phase Stefan problem with Neumann boundary data to a self-similar profile. (English)
[ Abstract ]
We study a one-dimensional one-phase Stefan problem with a Neumann boundary condition on the fixed part of the boundary.
We construct a unique self-similar solution and show that for a large class of initial data, the solution of the time evolution problem converges to this self-similar solution as time tends to infinity. Similar results were already obtained by Bouguezzi, Hilhorst, Miyamoto, and Scheid in the case of Dirichlet data on the fixed boundary. However, they had to show that the space derivative of the solution uniformly converges to its limit. Here, our proof requires less regularity, which should make our arguments easier to adapt to different settings.
This is a joint work with Sabrina Roscani and Piotr Rybka.
We study a one-dimensional one-phase Stefan problem with a Neumann boundary condition on the fixed part of the boundary.
We construct a unique self-similar solution and show that for a large class of initial data, the solution of the time evolution problem converges to this self-similar solution as time tends to infinity. Similar results were already obtained by Bouguezzi, Hilhorst, Miyamoto, and Scheid in the case of Dirichlet data on the fixed boundary. However, they had to show that the space derivative of the solution uniformly converges to its limit. Here, our proof requires less regularity, which should make our arguments easier to adapt to different settings.
This is a joint work with Sabrina Roscani and Piotr Rybka.
2024/01/26
thesis presentations
9:15-10:30 Room #118 (Graduate School of Math. Sci. Bldg.)
YAMAGUCHI Tatsuki (Graduate School of Mathematical Sciences University of Tokyo)
Studies on F-singularities in equal characteristic zero via ultraproducts
（超積を用いた等標数0におけるF-特異点の研究）
YAMAGUCHI Tatsuki (Graduate School of Mathematical Sciences University of Tokyo)
Studies on F-singularities in equal characteristic zero via ultraproducts
（超積を用いた等標数0におけるF-特異点の研究）
thesis presentations
9:15-10:30 Room #128 (Graduate School of Math. Sci. Bldg.)
INOUE Daisuke (Graduate School of Mathematical Sciences University of Tokyo)
Numerical Methods for Nonlinear Partial Differential Equations Arising from Large-Scale Multi-Agent Control Problems
（大規模マルチエージェント制御問題に現れる非線形偏微分方程式の数値計算）
INOUE Daisuke (Graduate School of Mathematical Sciences University of Tokyo)
Numerical Methods for Nonlinear Partial Differential Equations Arising from Large-Scale Multi-Agent Control Problems
（大規模マルチエージェント制御問題に現れる非線形偏微分方程式の数値計算）
thesis presentations
11:00-12:15 Room #118 (Graduate School of Math. Sci. Bldg.)
SHIMADA Ryosuke (Graduate School of Mathematical Sciences University of Tokyo)
Geometric Structure of Affine Deligne-Lusztig Varieties for GLn
（GLnのアファインDeligne-Lusztig多様体の幾何構造）
SHIMADA Ryosuke (Graduate School of Mathematical Sciences University of Tokyo)
Geometric Structure of Affine Deligne-Lusztig Varieties for GLn
（GLnのアファインDeligne-Lusztig多様体の幾何構造）
thesis presentations
11:00-12:15 Room #128 (Graduate School of Math. Sci. Bldg.)
ETO Tokuhiro (Graduate School of Mathematical Sciences University of Tokyo)
Numerical Analysis for Geometric Evolution Equations
（幾何学的発展方程式に対する数値解析）
ETO Tokuhiro (Graduate School of Mathematical Sciences University of Tokyo)
Numerical Analysis for Geometric Evolution Equations
（幾何学的発展方程式に対する数値解析）
thesis presentations
13:00-14:15 Room #126 (Graduate School of Math. Sci. Bldg.)
OIKAWA Mizuki (Graduate School of Mathematical Sciences University of Tokyo)
Equivariant α-induction Frobenius algebras and related constructions of tensor categories
（同変α-誘導フロベニウス代数と関連するテンソル圏の構成）
OIKAWA Mizuki (Graduate School of Mathematical Sciences University of Tokyo)
Equivariant α-induction Frobenius algebras and related constructions of tensor categories
（同変α-誘導フロベニウス代数と関連するテンソル圏の構成）
thesis presentations
14:45-16:00 Room #118 (Graduate School of Math. Sci. Bldg.)
KOIZUMI Junnosuke (Graduate School of Mathematical Sciences University of Tokyo)
Study of motives with modulus using Q-divisors
（モジュラス付きモチーフのQ因子を用いた研究）
KOIZUMI Junnosuke (Graduate School of Mathematical Sciences University of Tokyo)
Study of motives with modulus using Q-divisors
（モジュラス付きモチーフのQ因子を用いた研究）
thesis presentations
14:45-16:00 Room #122 (Graduate School of Math. Sci. Bldg.)
MIYAZAWA Jin (Graduate School of Mathematical Sciences University of Tokyo)
Real Seiberg-Witten theory and its applications to surfaces in 4-manifolds
（実Seiberg-Witten理論とその4次元多様体に埋め込まれた曲面への応用）
MIYAZAWA Jin (Graduate School of Mathematical Sciences University of Tokyo)
Real Seiberg-Witten theory and its applications to surfaces in 4-manifolds
（実Seiberg-Witten理論とその4次元多様体に埋め込まれた曲面への応用）
thesis presentations
14:45-16:00 Room #126 (Graduate School of Math. Sci. Bldg.)
HASHIBA Yasuhito (Graduate School of Mathematical Sciences University of Tokyo)
On the structure of crossed product von Neumann algebras
（接合積von Neumann環の構造について）
HASHIBA Yasuhito (Graduate School of Mathematical Sciences University of Tokyo)
On the structure of crossed product von Neumann algebras
（接合積von Neumann環の構造について）
thesis presentations
14:45-16:00 Room #128 (Graduate School of Math. Sci. Bldg.)
YAMAGISHI Hayate ( )
Asymptotic expansion of estimators related to diffusion processes driven by fractional Brownian motion
（非整数ブラウン運動によって駆動される拡散過程に関わる推定量の漸近展開）
YAMAGISHI Hayate ( )
Asymptotic expansion of estimators related to diffusion processes driven by fractional Brownian motion
（非整数ブラウン運動によって駆動される拡散過程に関わる推定量の漸近展開）
2024/01/25
Information Mathematics Seminar
16:50-18:35 Room #056 (Graduate School of Math. Sci. Bldg.)
Yasunari Suzuki (NTT)
Design and control of fault-tolerant quantum computer (Japanese)
Yasunari Suzuki (NTT)
Design and control of fault-tolerant quantum computer (Japanese)
[ Abstract ]
To demonstrate quantum computational advantage, we need quantum error-correction technology to reduce effective error rates to a small value. In this talk, we explain methods to fault-tolerantly control encoded logical information and methods to translate practical algorithms to basic operations.
To demonstrate quantum computational advantage, we need quantum error-correction technology to reduce effective error rates to a small value. In this talk, we explain methods to fault-tolerantly control encoded logical information and methods to translate practical algorithms to basic operations.
thesis presentations
9:15-10:30 Room #122 (Graduate School of Math. Sci. Bldg.)
TAKANO Akihiro (Graduate School of Mathematical Sciences University of Tokyo)
Studies on knot theory using braid groups and Thompson’s group
（組み紐群とトンプソン群を用いた結び目理論の研究）
TAKANO Akihiro (Graduate School of Mathematical Sciences University of Tokyo)
Studies on knot theory using braid groups and Thompson’s group
（組み紐群とトンプソン群を用いた結び目理論の研究）
thesis presentations
9:15-10:30 Room #128 (Graduate School of Math. Sci. Bldg.)
HIGASHI Kohei (Graduate School of Mathematical Sciences University of Tokyo)
Fuzzy cellular automaton and systems with singular integrals and their applications
（ファジーセルオートマトンおよび特異積分をもつシステムの数理とその応用）
HIGASHI Kohei (Graduate School of Mathematical Sciences University of Tokyo)
Fuzzy cellular automaton and systems with singular integrals and their applications
（ファジーセルオートマトンおよび特異積分をもつシステムの数理とその応用）
thesis presentations
11:00-12:15 Room #118 (Graduate School of Math. Sci. Bldg.)
Li Kimihiko (Graduate School of Mathematical Sciences University of Tokyo)
q-de Rham complexes of higher level
（高レベルq-ド・ラーム複体）
Li Kimihiko (Graduate School of Mathematical Sciences University of Tokyo)
q-de Rham complexes of higher level
（高レベルq-ド・ラーム複体）
thesis presentations
11:00-12:15 Room #122 (Graduate School of Math. Sci. Bldg.)
Wang Gefei (Graduate School of Mathematical Sciences University of Tokyo)
On the Rational Cohomology of Spin Hyperelliptic Mapping Class Groups
（スピン超楕円的写像類群の有理コホモロジーについて）
Wang Gefei (Graduate School of Mathematical Sciences University of Tokyo)
On the Rational Cohomology of Spin Hyperelliptic Mapping Class Groups
（スピン超楕円的写像類群の有理コホモロジーについて）
thesis presentations
11:00-12:15 Room #126 (Graduate School of Math. Sci. Bldg.)
WATANABE Yuta (Graduate School of Mathematical Sciences University of Tokyo)
Bogomolov-Sommese vanishing with multiplier ideals and studies on positivity of singular Hermitian metrics on holomorphic vector bundles
（乗数イデアル層を含むBogomolov-Sommese 消滅定理と正則ベクトル束の特異エルミート計量に関する正値性の研究）
WATANABE Yuta (Graduate School of Mathematical Sciences University of Tokyo)
Bogomolov-Sommese vanishing with multiplier ideals and studies on positivity of singular Hermitian metrics on holomorphic vector bundles
（乗数イデアル層を含むBogomolov-Sommese 消滅定理と正則ベクトル束の特異エルミート計量に関する正値性の研究）
thesis presentations
11:00-12:15 Room #128 (Graduate School of Math. Sci. Bldg.)
OHASHI Haruka (Graduate School of Mathematical Sciences University of Tokyo)
Construction of non-integrable three-state Markov processes with solvable steady states
（可解な定常分布をもつ非可積分3状態マルコフ過程の構成）
OHASHI Haruka (Graduate School of Mathematical Sciences University of Tokyo)
Construction of non-integrable three-state Markov processes with solvable steady states
（可解な定常分布をもつ非可積分3状態マルコフ過程の構成）
thesis presentations
13:00-14:15 Room #122 (Graduate School of Math. Sci. Bldg.)
PEREZ VALDES VICTOR (Graduate School of Mathematical Sciences University of Tokyo)
Construction and classification of matrix-valued differential symmetry breaking operators from S3 to S2
（3次元球面から2次元球面への対称性破れの行列値微分作用素の構成と分類について）
PEREZ VALDES VICTOR (Graduate School of Mathematical Sciences University of Tokyo)
Construction and classification of matrix-valued differential symmetry breaking operators from S3 to S2
（3次元球面から2次元球面への対称性破れの行列値微分作用素の構成と分類について）
thesis presentations
13:00-14:15 Room #126 (Graduate School of Math. Sci. Bldg.)
UEDA Kento (Graduate School of Mathematical Sciences University of Tokyo)
Error Distribution for One-Dimensional Stochastic Differential Equation Driven By Fractional Brownian motion
（非整数ブラウン運動で駆動される1次元確率微分方程式の誤差分布）
UEDA Kento (Graduate School of Mathematical Sciences University of Tokyo)
Error Distribution for One-Dimensional Stochastic Differential Equation Driven By Fractional Brownian motion
（非整数ブラウン運動で駆動される1次元確率微分方程式の誤差分布）
thesis presentations
14:45-16:00 Room #128 (Graduate School of Math. Sci. Bldg.)
HU XIN (Graduate School of Mathematical Sciences University of Tokyo)
On the hydrodynamic limit of the Boltzmann equation and its numerical computation
（ボルツマン方程式の流体力学極限とその数値計算について）
HU XIN (Graduate School of Mathematical Sciences University of Tokyo)
On the hydrodynamic limit of the Boltzmann equation and its numerical computation
（ボルツマン方程式の流体力学極限とその数値計算について）
2024/01/24
Classical Analysis
10:30-12:00 Room #122 (Graduate School of Math. Sci. Bldg.)
Gergő Nemes (Tokyo Metropolitan University)
On the Borel summability of formal solutions of certain higher-order linear ordinary differential equations (English)
Gergő Nemes (Tokyo Metropolitan University)
On the Borel summability of formal solutions of certain higher-order linear ordinary differential equations (English)
[ Abstract ]
We will consider a class of $n$th-order linear ordinary differential equations with a large parameter $u$. Analytic solutions of these equations can be described by (divergent) formal series in
descending powers of $u$. We shall demonstrate that, given mild conditions on the potential functions of the equation, the formal solutions are Borel summable with respect to the parameter $u$ in large, unbounded domains of the independent variable. We will establish that the formal series expansions serve as asymptotic expansions, uniform with respect to the independent variable, for the Borel re-summed exact solutions. Additionally, the exact solutions can be expressed using factorial series in the parameter, and these expansions converge in half-planes, uniformly with respect to the independent variable. To illustrate our theory, we apply it to an $n$th-order Airy-type equation.
Related preprint: https://arxiv.org/abs/2312.14449
We will consider a class of $n$th-order linear ordinary differential equations with a large parameter $u$. Analytic solutions of these equations can be described by (divergent) formal series in
descending powers of $u$. We shall demonstrate that, given mild conditions on the potential functions of the equation, the formal solutions are Borel summable with respect to the parameter $u$ in large, unbounded domains of the independent variable. We will establish that the formal series expansions serve as asymptotic expansions, uniform with respect to the independent variable, for the Borel re-summed exact solutions. Additionally, the exact solutions can be expressed using factorial series in the parameter, and these expansions converge in half-planes, uniformly with respect to the independent variable. To illustrate our theory, we apply it to an $n$th-order Airy-type equation.
Related preprint: https://arxiv.org/abs/2312.14449
Number Theory Seminar
17:00-18:00 Room #056 (Graduate School of Math. Sci. Bldg.)
Yong Suk Moon (BIMSA)
Purity for p-adic Galois representations (English)
Yong Suk Moon (BIMSA)
Purity for p-adic Galois representations (English)
[ Abstract ]
Given a smooth p-adic formal scheme, Tsuji proved a purity result for crystalline local systems on its generic fiber. In this talk, we will discuss a generalization for log-crystalline local systems on the generic fiber of a semistable p-adic formal scheme. This is based on a joint work with Du, Liu, and Shimizu.
Given a smooth p-adic formal scheme, Tsuji proved a purity result for crystalline local systems on its generic fiber. In this talk, we will discuss a generalization for log-crystalline local systems on the generic fiber of a semistable p-adic formal scheme. This is based on a joint work with Du, Liu, and Shimizu.
2024/01/23
Tuesday Seminar on Topology
17:00-18:00 Room #ハイブリッド開催/056 (Graduate School of Math. Sci. Bldg.)
Pre-registration required. See our seminar webpage.
Gefei Wang (The University of Tokyo)
On the rational cohomology of spin hyperelliptic mapping class groups (JAPANESE)
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
Pre-registration required. See our seminar webpage.
Gefei Wang (The University of Tokyo)
On the rational cohomology of spin hyperelliptic mapping class groups (JAPANESE)
[ Abstract ]
Let $G$ be the subgroup $S_{n−q} \times S_q$ of the $n$-th symmetric group $S_n$ for $n-q \ge q$. In this talk, we study the $G$-invariant part of the rational cohomology group of the pure braid group $P_n$. The invariant part $H^*(P_n)^G$ includes the rational cohomology of a spin hyperelliptic mapping class group of genus $g$ as a subalgebra when $n=2g+2$. Based on the study of Lehrer-Solomon, we prove that they are independent of n and q in degree $* \le q-1$. We also give a formula to calculate the dimension of $H^* (P_n)^G$ and calculate it in all degree for $q \le 3$.
[ Reference URL ]Let $G$ be the subgroup $S_{n−q} \times S_q$ of the $n$-th symmetric group $S_n$ for $n-q \ge q$. In this talk, we study the $G$-invariant part of the rational cohomology group of the pure braid group $P_n$. The invariant part $H^*(P_n)^G$ includes the rational cohomology of a spin hyperelliptic mapping class group of genus $g$ as a subalgebra when $n=2g+2$. Based on the study of Lehrer-Solomon, we prove that they are independent of n and q in degree $* \le q-1$. We also give a formula to calculate the dimension of $H^* (P_n)^G$ and calculate it in all degree for $q \le 3$.
https://park.itc.u-tokyo.ac.jp/MSF/topology/TuesdaySeminar/index_e.html
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