ニュース＆イベント

Math-Fi seminar on 14 May.

2026.05.14 Thu up
  • Date: 14 May. (Thu.) 
  • Place: West Wing, 6th floor, Colloquium Room and on the Web (zoom)
  • Time: 16:50-18:20
  • Speaker :  Alessio Rondelli (University of Bologna)
  • Title: McKean-Vlasov SDEs and particle systems: What, Why and How.
  • Abstract: 
McKean-Vlasov SDEs are a class of Stochastic Differential Equations
where the coefficients depend upon the marginals of the solution. Their
study is justified by their usefulness in modeling the evolution of
multi-agent systems using the mean-field approximation. Both classical
and modern techniques are presented for strong and weak well-posedness
and the concept of propagation of chaos gets explored.

Math-Fi seminar on 23 Apr. (Co-organized as a Quantum Walk Seminar)

2026.04.23 Thu up
  • Date: 23 Apr. (Thu.)
  • Place: West Wing, 6th floor, Colloquium Room and on the Web (zoom)
  • Time: 16:50-17:50
  • Speaker : Hiromichi OHNO (Shinshu University)
  • Title: Maze solving by quantum walk
  • Abstract: 
本講演では，グラフを迷路に見立て，スタートとゴールを設定し，グローバーウォークを用いてスタートからゴールまでの経路を発見するアルゴリズムについて解説する．このアルゴリズムでは，量子ウォークの収束することは示せているが，収束先の確率分布から経路を発見できるかどうかは部分的な解答しか得られていない．これらの内容について数学的な証明を与えながら，具体的ないくつかの例を紹介する．

Math-Fi seminar on 17 Apr.

2026.04.16 Thu up
  • Date: 17 Apr. (Thu.) 
  • Place: West Wing, 6th floor, Colloquium Room and on the Web (zoom)
  • Time: 16:20-17:50
  • Speaker :  Antoine Jacquier (Imperial College)
  • Title: Quantum Computing, a new toolbox for Stochastic Analysis & Machine Learning?
  • Abstract: 
We are interested here in recent developments in Quantum Computing from an algorithmic standpoint and with a view towards applications (with an emphasis on Mathematical Finance and Stochastic Analysis). We shall in particular focus on Universal Approximations theorems for Parameterised Quantum Circuits as well as on the links between (partial) measurements of Quantum systems and Stochastic diffusions.

Math-Fi seminar on 9 Apr. (Co-organized as a Quantum Walk Seminar)

2026.04.09 Thu up
  • Date: 9 Apr. (Thu.)
  • Place: West Wing, 6th floor, Colloquium Room and on the Web (zoom)
  • Time: 16:50-17:50
  • Speaker : Yohei Tanaka (Ritsumeikan University)
  • Title: On understanding chiral unitaries via real parts
  • Abstract: 
We study unitary operators with chiral symmetry, that is, unitary operators associated with a fixed involution. Such operators naturally arise in the study of quantum walks and related areas. A standard approach is to decompose the underlying Hilbert space according to this symmetry, which leads to a convenient block representation. In this framework, we focus on the real part of the unitary and use it as a useful tool to understand its spectral structure. Based on this viewpoint, we present several related topics and results, illustrating how the real-part perspective provides a simple and unified way to analyze chiral unitaries.

立命館大学 集中セミナー

2026.04.07 Tue up
  • Date: 9月14日－18日
  • Place: ウエストウィング6階談話会室あるいは７階のセミナー室　対面およびオンライン
  • Time: 
9月14日(月)～17日 (木)
2コマ:  
(1) 13:30～15:00
(2) 15:15～16:45
9月18日 (金)
1コマ13:30～15:00
  • Speaker :  日合文雄（東北大学名誉教授）
  • Title: 行列解析と量子情報への応用 
  • Abstract: 
この集中セミナーでは，最初に作用素平均と作用素パースペクティブを復習してから，作用素・
行列の作用素不等式，マジョリゼーション，トレース不等式などを解説する．次に，量子情報
で重要な種々の量子f-ダイバージェンスを説明する．特に最近発展しているホッケースチック
f-ダイバージェンスを取り上げる．さらに，量子情報幾何で重要なFisher 情報量（単調計量）
と関連するいくつかの話題を解説する．
 
 
 

Math-Fi seminar on 2 Apr.

2026.04.07 Tue up
  • Date: 2 Apr. (Thu.) 
  • Place: West Wing, 6th floor, Colloquium Room and on the Web (zoom)
  • Time: 12:00-13:30
  • Speaker :  VU HUY HOANG (University of California, Santa Barbara)
  • Commentator :  Ju-Yi Yen (University of Cincinnati)
  • Title: Molchanov’s Formula and Quantum Walks: A Probabilistic Approach 
  • Abstract: 
This paper establishes a robust link between quantum dynamics and classical ones by deriving a probabilistic representation for both continuous-time and discrete-time quantum walks. We first adapt the Molchanov formula, originally employed in the study of Schrodinger operators on multidimensional integer lattices, to characterize the evolution of continuous time quantum walks. Extending this framework, we develop a probabilistic method to represent discrete time quantum walks on an infinite integer line, bypassing the locality constraints that typically inhibit direct application of the Molchanov formula. The validity of our representation is empirically confirmed through a benchmark analysis of the Hadamard walk, demonstrating high fidelity with traditional unitary evolution. Our results suggest that this probabilistic lens offers a powerful alternative for learning multidimensional quantum walks and provides new analytical pathways for investigating quantum systems via classical stochastic processes.

Math-Fi seminar on 31 Mar.

2026.04.07 Tue up
  • Date: 31 Mar. (Tue.) 
  • Place: West Wing, 6th floor, Colloquium Room and on the Web (zoom)
  • Time: 16:00–17:30 
  • Speaker : Joseph Najnudel (University of Bristol)  
  • Commentator :  Ju-Yi Yen (University of Cincinnati)
  • Title: The Riemann zeta function and its connection with random matrix theory.
  • Abstract: 
In this talk, we present some results and conjectures on the Riemann zeta function, its moments on the critical line, its extreme values, and its behaviour at the scale of the average spacing of the zeros.  We then connect these results to similar properties satisfied by the characteristic polynomial of random unitary matrices.

Ritsumeikan Geometry Seminar on 13 Mar.

2026.02.27 Fri up
Date: March 13, Friday, 2026 
Place: Colloquium room, West-Wing 6F, Biwako-Kusatsu Campus + Zoom meeting
Registration URL for Zoom:
https://ritsumei-ac-jp.zoom.us/meeting/register/A90nnMv0RNC7PFizhntG_w
 
 
-Program- (modified on March 1)
 
15:20-16:20 Steven Hurder (University of Illinois at Chicago)
      The dynamics of commensurators

16:30-17:30 Olga Lukina (Leiden University)
      Cantor actions in dynamical systems
 

 
-Abstract-
  • Speaker 1: Steven Hurder (University of Illinois at Chicago)
  • Title: The dynamics of commensurators
  • Abstract:
A commensurator of a countable group G is a virtual automorphism. That is, it is an isomorphism f : H -> K where H and K are subgroups of finite index of G.  We associate to a commensurator f of G, a homeomorphism F : C -> C of a Cantor set C. In the general case the space C is the profinite completion of G, but our interest is in more general case where C is a quotient of the profinite completion of G. We study the dynamical properties of the map F : C -> C. 
 
  • Speaker 2: Olga Lukina (Leiden University)
  • Title: Cantor actions in dynamical systems
  • Abstract:
In this talk, we consider dynamical systems on Cantor sets, given by group actions. Such systems arise as transverse dynamical systems in strange attractors and exceptional minimal sets of foliations. We present a few classification results.

 
Organizers:
Fukumoto Yoshihiro, Tarama Daisuke, Nozawa Hiraku
 
Contact:
hnozawa@fc.ritsumei.ac.jp

Math-Fi seminar on 12 Feb.

2026.02.10 Tue up
  • Date: 12 Feb. (Thu.) 
  • Place: West Wing, 6th floor, Colloquium Room and on the Web (zoom)
  • Time: 16:00–17:30 
  • Speaker : George Yin (University of Connecticut)
  • Title: Stochastic Approximation and Applications
  • Abstract: 
We will give an introduction to stochastic approximation
methods.  It will begin with a discussion on what stochastic approximation is and
what problems can be solved by using stochastic approximation methods. The RM and KW algorithms will be introduced.  An overview of the analysis (including convergence, rates of convergence, weak convergence, efficiency, as well as time-varying parameter problems, and tracking  algorithms etc.) is provided.  Several application examples will be mentioned.
A reference for the talk is the book by H.J. Kushner and G. Yin,
Stochastic Approximation and Recursive Algorithms and Applications, 2nd Edition,
Springer-Verlag, New York, 2003, [Applications of Mathematics, Volume 35].

立命館大学幾何学セミナー（2026年1月20日（火））

2026.01.16 Fri up
<<立命館大学幾何学セミナー>>
日時：2026年1月20日（火）16:45-20:00
プログラム：
16:45-18:00 講演
18:00-20:00 ディスカッション
講演者：松添 博 （名古屋工業大学）
題目：
推定関数の幾何学
概要：
情報幾何学は，確率測度の族を多様体とみなし，測度間の識別可能性などを計量や接続を用いて微分幾何学的に記述する理論である。
Fisher情報行列は自然な計量を与えるとともに，双対接続の導入により，最尤推定法をはじめとするさまざまな推定原理が幾何学的に記述される。
この枠組みを推定関数の立場から捉えると，推定関数は多様体上の接ベクトルに対応し，その選び方によって異なる推定方法が構成される。
本講演では，情報幾何学の基本的な考え方を概観したのち，推定関数の視点から情報幾何学における双対性などの構造について考察する。
 
開催方法： 立命館大学びわこ・くさつキャンパス，ウェストウィング6階談話会室での対面開催．
講演の模様をZoomミーティングで配信する予定です．
講演へのオンライン参加をご希望の方は以下のリンクよりお申し込みください：
 
 
登録された方にメールにてZoomミーティングに関する情報が届きます．

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