立命館大学数理科学科 » 2026年度 http://www.math.ritsumei.ac.jp/home2 立命館大学理工学部数理科学科です。幅広い領域での数学の研究・活用を通して人類の福祉と発展に貢献できる人材を育成することを目標としています。 Thu, 21 May 2026 04:16:43 +0000 ja hourly 1 https://wordpress.org/?v=3.9.40 Math-Fi seminar on 21 May. http://www.math.ritsumei.ac.jp/home2/?p=2302 http://www.math.ritsumei.ac.jp/home2/?p=2302#comments Thu, 21 May 2026 04:05:29 +0000 http://www.math.ritsumei.ac.jp/home2/?p=2302
  • Date: 21 May. (Thu.) 
  • Place: West Wing, 6th floor, Colloquium Room and on the Web (zoom)
  • Time: 16:50-18:20
  • Speaker :  Naoki Masuda (University of Michigan)
  • Title: 高次ネットワーク上の意見形成確率モデル
  • Abstract: 
    • 本講演では、まず、ネットワーク科学という研究分野の簡単な紹介を行う。次に、いくつかの種類の高次ネットワーク上の進化ダイナミクスの研究について紹介する。進化ダイナミクスは、本研究の範囲で言えば、平たく言うと、集団意見形成ダイナミクスを表す確率過程である。高次ネットワークとしては、近年のネットワーク科学で盛んに研究されている構造でもあるハイパーグラフ、多層ネットワーク、テンポラル（＝ネットワーク自体が時間変化する）・ネットワークを考える。（逆に、高次でないネットワークは、典型的なネットワーク、すなわち数学で言う「グラフ」のことを表す。）これらの高次ネットワーク上での上記確率過程の振る舞いは、典型的なネットワークの上での同じ確率過程と比べてかなり異なる。具体的には、ネットワークが進化の「増幅器」でありやすいか、「抑制器」でありやすいか、が異なる。このことを、マルチンゲール解析、数値計算などによって示す。
     

    ]]>     http://www.math.ritsumei.ac.jp/home2/?feed=rss2&p=2302 0     Math-Fi seminar on 14 May. http://www.math.ritsumei.ac.jp/home2/?p=2300 http://www.math.ritsumei.ac.jp/home2/?p=2300#comments Thu, 14 May 2026 02:51:49 +0000 http://www.math.ritsumei.ac.jp/home2/?p=2300
  • 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.
    ]]>     http://www.math.ritsumei.ac.jp/home2/?feed=rss2&p=2300 0     Math-Fi seminar on 23 Apr. (Co-organized as a Quantum Walk Seminar) http://www.math.ritsumei.ac.jp/home2/?p=2297 http://www.math.ritsumei.ac.jp/home2/?p=2297#comments Thu, 23 Apr 2026 07:15:53 +0000 http://www.math.ritsumei.ac.jp/home2/?p=2297
  • 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．
    ]]>     http://www.math.ritsumei.ac.jp/home2/?feed=rss2&p=2297 0     Math-Fi seminar on 17 Apr. http://www.math.ritsumei.ac.jp/home2/?p=2295 http://www.math.ritsumei.ac.jp/home2/?p=2295#comments Thu, 16 Apr 2026 07:41:03 +0000 http://www.math.ritsumei.ac.jp/home2/?p=2295
  • 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.
    ]]>     http://www.math.ritsumei.ac.jp/home2/?feed=rss2&p=2295 0     Math-Fi seminar on 9 Apr. (Co-organized as a Quantum Walk Seminar) http://www.math.ritsumei.ac.jp/home2/?p=2291 http://www.math.ritsumei.ac.jp/home2/?p=2291#comments Thu, 09 Apr 2026 06:15:09 +0000 http://www.math.ritsumei.ac.jp/home2/?p=2291
  • 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.
    ]]>     http://www.math.ritsumei.ac.jp/home2/?feed=rss2&p=2291 0     Math-Fi seminar on 2 Apr. http://www.math.ritsumei.ac.jp/home2/?p=2287 http://www.math.ritsumei.ac.jp/home2/?p=2287#comments Tue, 07 Apr 2026 01:51:01 +0000 http://www.math.ritsumei.ac.jp/home2/?p=2287
  • 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.
    ]]>     http://www.math.ritsumei.ac.jp/home2/?feed=rss2&p=2287 0