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Last Updated :2024/07/25

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Master

Affiliation (Master)

  • Research Institute for Electronic Science　Biology and Life Sciences

Affiliation (Master)

  • Research Institute for Electronic Science　Biology and Life Sciences

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Profile and Settings

Profile and Settings

  • Name (Japanese)

    Sato

  • Name (Kana)

    Yuzuru

  • Name

    201101014897326199

Alternate Names

Achievement

Research Interests

  • Nonlinear phenomena   Non-autonomous dynamical systems   Stochastic bifurcation   Noise-induced phenomena   Stochastic chaos   Random dynamical systems   Complex systems   Spatio-temporal chaos   Fluctuation and noise   Chaos   Dynamical systems   

Research Areas

  • Natural sciences / Applied mathematics and statistics
  • Natural sciences / Mathematical physics and basic theory
  • Informatics / Sensitivity (kansei) informatics
  • Informatics / Soft computing

Research Experience

  • 2013/09 - Today London Mathematical Laboratory External Fellow
  • 2006 - Today Hokkaido University RIES/Department of Mathematics Associate professor
  • 2002 - 2006 Santa Fe Institute Postdoctoral Fellow
  • 2001 - 2002 RIKEN Special Postdoctoral Researcher
  • 2000 - 2001 University of Tokyo / JSPS Postdoctoral researcher

Education

  • 1997/04 - 2000/03  University of Tokyo  Graduate School of Arts and Sciences

Awards

  • 2013/09 London Mathematical Laboratory LML External Fellowship
     
    受賞者: Yuzuru Sato
  • 1998/06 Santa Fe Institute Complex Systems Summer School Fellowship
     
    受賞者: Yuzuru Sato

Published Papers

  • Yuzuru Sato, Daiji Tsutsui, Akio Fujiwara
    Physica D: Nonlinear Phenomena 430 133095 - 133095 0167-2789 2022/02 [Refereed]
  • Takumi Chihara, Yuzuru Sato, Isaia Nisoli, Stefano Galatolo
    Chaos: An Interdisciplinary Journal of Nonlinear Science 32 (1) 013117 - 013117 1054-1500 2022/01 [Refereed]
  • Yoshito Hirata, Yuzuru Sato, Davide Faranda
    Chaos 30 (10) 103103 - 103103 1054-1500 2020/10/01 [Refereed]
     
    It has been shown that a permutation can uniquely identify the joint set of an initial condition and a non-autonomous external force realization added to the deterministic system in given time series data. We demonstrate that our results can be applied to time series forecasting as well as the estimation of common external forces. Thus, permutations provide a convenient description for a time series data set generated by non-autonomous dynamical systems.
  • Davide Faranda, Isaac Pérez Castillo, Oliver Hulme, Aglaé Jezequel, Jeroen S.W. Lamb, Yuzuru Sato, Erica L. Thompson
    Chaos 30 (5) 051107 - 051107 1054-1500 2020/05/01 [Refereed]
     
    Despite the importance of having robust estimates of the time-asymptotic total number of infections, early estimates of COVID-19 show enormous fluctuations. Using COVID-19 data from different countries, we show that predictions are extremely sensitive to the reporting protocol and crucially depend on the last available data point before the maximum number of daily infections is reached. We propose a physical explanation for this sensitivity, using a susceptible-exposed-infected-recovered model, where the parameters are stochastically perturbed to simulate the difficulty in detecting patients, different confinement measures taken by different countries, as well as changes in the virus characteristics. Our results suggest that there are physical and statistical reasons to assign low confidence to statistical and dynamical fits, despite their apparently good statistical scores. These considerations are general and can be applied to other epidemics.
  • 佐藤譲, 佐藤譲
    日本物理学会誌 75 (5) 0029-0181 2020 [Not refereed]
  • Davide Faranda, Yuzuru Sato, Gabriele Messori, Nicholas R. Moloney, Pascal Yiou
    Earth System Dynamics 10 (3) 555 - 567 2190-4979 2019/09/19 [Refereed][Not invited]
     
    We derive a minimal dynamical systems model for the Northern Hemisphere midlatitude jet dynamics by embedding atmospheric data and by investigating its properties (bifurcation structure, stability, local dimensions) for different atmospheric flow regimes. The derivation is a three-step process: first, we obtain a 1-D description of the midlatitude jet stream by computing the position of the jet at each longitude using ERA-Interim. Next, we use the embedding procedure to derive a map of the local jet position dynamics. Finally, we introduce the coupling and stochastic effects deriving from both atmospheric turbulence and topographic disturbances to the jet. We then analyze the dynamical properties of the model in different regimes: one that gives the closest representation of the properties extracted from real data; one featuring a stronger jet (strong coupling); one featuring a weaker jet (weak coupling); and one with modified topography. Our model, notwithstanding its simplicity, provides an instructive description of the dynamical properties of the atmospheric jet.
  • Yuzuru Sato, Rainer Klages
    Physical Review Letters 122 (17) 174101  0031-9007 2019/04/29 [Refereed][Not invited]
     
    Consider a chaotic dynamical system generating diffusionlike Brownian motion. Consider a second, nonchaotic system in which all particles localize. Let a particle experience a random combination of both systems by sampling between them in time. What type of diffusion is exhibited by this random dynamical system? We show that the resulting dynamics can generate anomalous diffusion, where in contrast to Brownian normal diffusion the mean square displacement of an ensemble of particles increases nonlinearly in time. Randomly mixing simple deterministic walks on the line, we find anomalous dynamics characterized by aging, weak ergodicity breaking, breaking of self-averaging, and infinite invariant densities. This result holds for general types of noise and for perturbing nonlinear dynamics in bifurcation scenarios.
  • Nicholas R. Moloney, Davide Faranda, Yuzuru Sato
    Chaos 29 (2) 022101  1054-1500 2019/02/01 [Refereed][Not invited]
     
    For a wide class of stationary time series, extreme value theory provides limiting distributions for rare events. The theory describes not only the size of extremes but also how often they occur. In practice, it is often observed that extremes cluster in time. Such short-range clustering is also accommodated by extreme value theory via the so-called extremal index. This review provides an introduction to the extremal index by working through a number of its intuitive interpretations. Thus, depending on the context, the extremal index may represent (i) the loss of independently and identically distributed degrees of freedom, (ii) the multiplicity of a compound Poisson point process, and (iii) the inverse mean duration of extreme clusters. More recently, the extremal index has also been used to quantify (iv) recurrences around unstable fixed points in dynamical systems.
  • Kunihiko Esashi, Tamotsu Onozaki, Yoshitaka Saiki, Yuzuru Sato
    Structural Change and Economic Dynamics 44 68 - 76 0954-349X 2018/03/01 [Refereed][Not invited]
     
    Empirical studies often conclude that multi-regional business cycles exhibit intermittent transition between synchronization and desynchronization of each regional fluctuations. In this study, we robustly observe this behavior (called chaotic itinerancy) in a model of multi-regional business cycles, in which all regions of a national economy are homogeneous and connected through producers’ behavior based on the average level announced by the government. Although a producer very slowly adjusts his/her output towards the average level, regional business cycles begin to synchronize because of the entrainment effect. Moreover, when a producer emphasizes the profit maximization more and when puts more weight on the average level in his/her decision-making, the economy is more likely to exhibit such intermittent transition. Further, it is clarified that behind intermittent transition exist cycles among periodic orbits with different number of unstable directions.
  • D. Faranda, Y. Sato, B. Saint-Michel, C. Wiertel, V. Padilla, B. Dubrulle, F. Daviaud
    Physical Review Letters 119 (1) 014502  0031-9007 2017/07/07 [Refereed][Not invited]
     
    We report the experimental evidence of the existence of a random attractor in a fully developed turbulent swirling flow. By defining a global observable which tracks the asymmetry in the flux of angular momentum imparted to the flow, we can first reconstruct the associated turbulent attractor and then follow its route towards chaos. We further show that the experimental attractor can be modeled by stochastic Duffing equations, that match the quantitative properties of the experimental flow, namely, the number of quasistationary states and transition rates among them, the effective dimensions, and the continuity of the first Lyapunov exponents. Such properties can be recovered neither using deterministic models nor using stochastic differential equations based on effective potentials obtained by inverting the probability distributions of the experimental global observables. Our findings open the way to low-dimensional modeling of systems featuring a large number of degrees of freedom and multiple quasistationary states.
  • Anna Maria Cherubini, Jeroen S.W. Lamb, Martin Rasmussen, Yuzuru Sato
    Nonlinearity 30 (7) 2835 - 2853 0951-7715 2017/06/07 [Refereed][Not invited]
     
    We study stochastic resonance in an over-damped approximation of the stochastic Duffing oscillator from a random dynamical systems point of view. We analyse this problem in the general framework of random dynamical systems with a nonautonomous forcing. We prove the existence of a unique global attracting random periodic orbit and a stationary periodic measure. We use the stationary periodic measure to define an indicator for the stochastic resonance.
  • Stochastic chaos in random dynamical systems
    Yuzuru Sato
    RIMS Technical Report (No.2028) pp.1-8  2017 [Not refereed][Not invited]
  • Davide Faranda, Giacomo Masato, Nicholas Moloney, Yuzuru Sato, Francois Daviaud, Bérengère Dubrulle, Pascal Yiou
    Climate Dynamics 47 (5-6) 1587 - 1599 0930-7575 2016/09/01 [Refereed][Not invited]
     
    Atmospheric mid-latitude circulation is dominated by a zonal, westerly flow. Such a flow is generally symmetric, but it can be occasionally broken up by blocking anticyclones. The subsequent asymmetric flow can persist for several days. In this paper, we apply new mathematical tools based on the computation of an extremal index in order to reexamine the dynamical mechanisms responsible for the transitions between zonal and blocked flows. We discard the claim that mid-latitude circulation features two distinct stable equilibria or chaotic regimes, in favor of a simpler mechanism that is well understood in dynamical systems theory: we identify the blocked flow as an unstable fixed point (or saddle point) of a single basin chaotic attractor, dominated by the westerlies regime. We also analyze the North Atlantic Oscillation and the Arctic Oscillation atmospheric indices, whose behavior is often associated with the transition between the two circulation regimes, and investigate analogies and differences with the bidimensional blocking indices. We find that the Arctic Oscillation index, which can be thought as a proxy for a hemispheric average of the Tibaldi-Molteni blocking index, tracks unstable fixed points. On the other hand, the North Atlantic Oscillation, representative only for local properties of the North Atlantic blocking dynamics, does not show any trace of the presence of unstable fixed points of the dynamics.
  • Sato Yuzuru, Ay Nihat
    IEICE NONLINEAR THEORY AND ITS APPLICATIONS 電子情報通信学会(The Institute of Electronics, Information and Communication Engineers / IEICE) 7 (2) 118 - 125 2185-4106 2016 [Refereed][Not invited]
     
    Information flow in adaptively interacting stochastic processes is studied. We give an extended form of game dynamics for interacting Markovian processes and compute a measure of causal information flow, which is different from the transfer entropy. In the game theoretic situation, causal information flow can show oscillatory behavior through reward-maximizing adaptation of two players. The adaptive dynamics for the coin-tossing game is exemplified and the causal information flow therein is investigated.
  • Sato Yuzuru, Shimaoka Daisuke, Fujimoto Koichi, Taga Gentaro
    IEICE NONLINEAR THEORY AND ITS APPLICATIONS 電子情報通信学会(The Institute of Electronics, Information and Communication Engineers / IEICE) 7 (2) 226 - 233 2185-4106 2016 [Refereed][Not invited]
     
    We propose an extended framework of two dimensional neural field with network between distant cortical areas as a model of global brain dynamics, and the models whose geometry of the neural field changes depending on the field dynamics as a model for growing brains. As a characteristic pattern with non-local and network interactions in neural field, pulser and memory are constructed. Possible applications to quantitative measurements of cortical activities of mouse and human brain development are briefly discussed.
  • Robust pattern construction in two-dimensional neural field
    Yuzuru Sato
    Proc. of AFCA pp.85-89  2015 [Refereed][Not invited]
  • The switching between zonal and blocked mid-latitude atmospheric circulation: a dynamical system perspective
    Davide Faranda, Giacomo Masato, Nicholas Moloney, Yuzuru Sato, Francois Daviaud, Berengere Dubrulle, Pascal Yiou
    Climate Dynamics pp 1-13  2015 [Refereed][Not invited]
  • ランダム力学系と確率カオス
    佐藤譲
    数理科学 2015年8月号 26 - 31 2015 [Not refereed][Not invited]
  • Random basin in dice roll
    Y. Sato, N. Matsunaga
    RIMS Technical Report 1942 1 - 10 2015 [Not refereed][Not invited]
  • Kota Hiratsuka, Yuzuru Sato, Zin Arai
    NOLTA 5 (4) 410 - 423 2185-4106 2014 [Refereed][Not invited]
     
    Since A.M. Turing introduced the notion of computability in 1936, various theories of real number computation have been studied [1, 10, 13]. Some are of interest in nonlinear and statistical physics while others are extensions of the mathematical theory of computation. In this review paper, we introduce a recently developed computability theory for Julia sets in complex dynamical systems by Braverman and Yampolsky [3].
  • Random dynamical systems modeling for brain wave synchrony
    Kazuhiro Matsumoto, Yuzuru Sato, Hiroshi Endo, Keiichi Kitajo
    Proc. of NOLTA 2013 395 - 398 2013 [Refereed][Not invited]
  • Robust computation in two dimensional neural field
    Yuzuru Sato, Shun-ichi Amari
    Advances in Cognitive Neurodynamics 123 - 129 2013 [Refereed][Not invited]
  • Computability and Complexity of Julia Sets
    Kota Hiratsuka, Yuzuru Sato, Zin Arai
    Proc. of NOLTA 2013 2 - 5 2013 [Refereed][Not invited]
  • Random dynamics from time series
    Yuzuru Sato
    RIMS Technical Report 1827 24 - 32 2012 [Not refereed][Not invited]
  • Random dynamics from time-serieses of physiological rhythms.
    Yuzuru Sato, Kazuhiro Matsumoto
    Proc. of NOLTA 2012 497 - 500 2012 [Refereed][Not invited]
  • Miguel Angel Fuentes, Yuzuru Sato, Constantino Tsallis
    Physics Letters, Section A: General, Atomic and Solid State Physics 375 (33) 2988 - 2991 0375-9601 2011/08/01 [Refereed][Not invited]
     
    We analytically link three properties of nonlinear dynamical systems, namely sensitivity to initial conditions, entropy production, and escape rate, in z-logistic maps for both positive and zero Lyapunov exponents. We unify these relations at chaos, where the Lyapunov exponent is positive, and at its onset, where it vanishes. Our result unifies, in particular, two already known cases, namely (i) the standard entropy rate in the presence of escape, valid for exponential functionality rates with strong chaos, and (ii) the Pesin-like identity with no escape, valid for the power-law behavior present at points such as the Feigenbaum one. (C) 2011 Elsevier B.V. All rights reserved.
  • Yao Lu, Yuzuru Sato, Shun Ichi Amari
    Neural Computation 23 (5) 1248 - 1260 0899-7667 2011/05 [Refereed][Not invited]
     
    A neural field is a continuous version of a neural network model accounting for dynamical pattern forming from populational firing activities in neural tissues. These patterns include standing bumps, moving bumps, traveling waves, target waves, breathers, and spiral waves, many of them observed in various brain areas. They can be categorized into two types: a wave-like activity spreading over the field and a particle-like localized activity. We show through numerical experiments that localized traveling excitation patterns (traveling bumps), which behave like particles, exist in a two-dimensional neural field with excitation and inhibition mechanisms. The traveling bumps do not require any geometric restriction (boundary) to prevent them from propagating away, a fact that might shed light on how neurons in the brain are functionally organized. Collisions of traveling bumps exhibit rich phenomena; they might reveal the manner of information processing in the cortex and be useful in various applications. The trajectories of traveling bumps can be controlled by external inputs.
  • Random dynamics from time-seriese of rotating fluid
    Yuzuru Sato, Makoto Iima, Yuji Tasaka
    Hokkaido University Technical Report 979 2011 [Not refereed][Not invited]
  • Makoto Iima, Yu Iijima, Yuzuru Sato, Yuji Tasaka
    Theoretical and Applied Mechanics Japan 59 187 - 193 1348-0693 2011 [Refereed][Not invited]
     
    We study the free-surface dynamics of rotational flow by time series analysis. In a flow driven by a rotating disk in a cylinder, the free surface irregularly switches between an axisymmetric shape and a nonaxisymmetric shape. This surface switching occurs in combination with significant elevation and elongation of the central part whose height has a strong correlation with the turbulent intensity. Although the number of degrees of freedom for the entire system is considerably large, the surface-shape dynamics indicates that the dimension needed to describe the major motion is much smaller compared with the whole system and the remaining part constitutes noise added to the major part. We have evaluated this conjecture by applying a diagnostic method and have clarified that the time series of the surface height is different from the white noise and the surrogate data of the original time series, both of which have no determinism. © 2011 by National Committee for IUTAM.
  • Sato Yuzuru
    RIMS Kokyuroku 京都大学 1688 137 - 143 1880-2818 2010/05 [Not refereed][Not invited]
  • 回転流体自由界面の不規則スイッチングにおける底面-側壁ギャップの影響
    田坂 裕司, 飯間 信, 佐藤 讓
    日本流体力学会年会2010拡張要旨集 2010 [Not refereed][Not invited]
  • オートマトンモデルの背景
    佐藤譲
    現代思想「現代数学の思考法」 2010年9月号 155 - 163 2010 [Not refereed][Not invited]
  • 佐藤 讓, 飯間 信, 田坂 裕司
    第59回理論応用力学講演会講演論文集 145 - 146 2010 [Not refereed][Not invited]
  • 飯間 信, 飯島 悠宇, 佐藤 讓, 田坂 裕司
    第59回理論応用力学講演会講演論文集 143 - 144 2010 [Not refereed][Not invited]
  • SATO Yuzuru
    IEICE technical report 社団法人電子情報通信学会 109 (269) 221 - 223 0913-5685 2009/11 [Not refereed][Not invited]
     
    Noise-induced phenomena in unimodal maps are re-investigated and a new phenomenon numerically observed in logistic map and Belousov-Zhabotinsky map (BZ map) with presence of additive noise is reported. We found that (i) noise-induced chaos and noise-induced order coexist depending on size of fluctuation of noise, and that (ii) these phenomena are robustly observed in the window region of BZ map, indicated by numerically calculated Lyapunov exponents. A physically tractable framework for random dynamical systems is discussed to study observability of potentially chaotic systems.
  • 自由表面大変形を伴う円筒容器内の回転流れの実験および数理的解析
    飯間 信, 田坂 裕司, 佐藤 讓, 眞山 博幸
    日本流体力学会年会2008講演論文集 2008 [Not refereed][Not invited]
  • ルールを生成する力学系: 関数マップ概説
    佐藤譲
    統計数理研究所共同研究リポート 217 33 - 44 2008 [Not refereed][Not invited]
  • Random Dynamics from Time Seriese of Rotating Fluid
    Yuzuru Sato, Makoto Iima, Yuji Tasaka
    Proceedings of JSIAM 08 317 - 318 2008 [Not refereed][Not invited]
  • Yuzuru Sato, Constantino Tsallis
    International Journal of Bifurcation and Chaos 16 (6) 1727 - 1738 0218-1274 2006/06 [Refereed][Not invited]
     
    Many natural and artificial systems whose range of interaction is long enough are known to exhibit (quasi) stationary states that defy the standard, Boltzmann-Gibbs statistical mechanical prescriptions. For handling such anomalous systems (or at least some classes of them), nonextensive statistical mechanics has been proposed based on the entropy S-q = k (1 - Sigma(w)(i-1) p(i)(q))/(q - 1), with S-1 = -k Sigma(w)(i=1) p(i)lnp(i) (Boltzmann-Gibbs entropy). Special collective correlations can be mathematically constructed such that the strictly additive entropy is now S-q for an adequate value of q not equal 1, whereas Boltzmann-Gibbs entropy is nonadditive. Since important classes of systems exist for which the strict additivity of Boltzmann-Gibbs entropy is replaced by asymptotic additivity (i.e. extensivity), a variety of classes are expected to exist for which the strict additivity of S-q (q not equal 1) is similarly replaced by asymptotic additivity (i.e. extensivity). All probabilistically well defined systems whose adequate entropy is S-1 are called extensive (or normal). They correspond to a number W-eff of effectively occupied states which grows exponentially with the number N of elements (or subsystems). Those whose adequate entropy is S-q (q not equal 1) are currently called nonextensive (or anomalous). They correspond to W-eff growing like a power of N. To illustrate this scenario, recently addressed [Tsallis, 2004] we provide in this paper details about systems composed by N = 2, 3 two-state subsystems.
  • Constantino Tsallis, Murray Gell-Mann, Yuzuru Sato
    Proceedings of the National Academy of Sciences of the United States of America 102 (43) 15377 - 15382 0027-8424 2005/10/25 [Refereed][Not invited]
     
    Phase space can be constructed for N equal and distinguishable subsystems that could be probabilistically either weakly correlated or strongly correlated. If they are locally correlated, we expect the Boltzmann-Gibbs entropy S(BG) equivalent to -k Sigma(i) p(i) In p(i) to be extensive, i.e., S(BG)(N) proportional to N for N -> infinity. In particular, if they are independent, S(BG) is strictly additive, i.e., S(BG)(N) = NS(BG)(1), for all N. However, if the subsystems are globally correlated, we expect, for a vast class of systems, the entropy S(q) equivalent to k[l - Sigma(i) p(i)(q)]/(q - 1) (with S(1) = S(BG)) for some special value of q not equal 1 to be the one which is extensive [i.e., Sq(N) proportional to N for N -> infinity]. Another concept which is relevant is strict or asymptotic scale-freedom (or scale-in variance), defined as the situation for which all marginal probabilities of the N-system coincide or asymptotically approach (for N -> infinity) the joint probabilities of the (N - 1)-system. If each subsystem is a binary one, scale-freedom is guaranteed by what we hereafter refer to as the Leibnitz rule, i.e., the sum of two successive joint probabilities of the N-system coincides or asymptotically approaches the corresponding joint probability of the (N - 1)-system. The kinds of interplay of these various concepts are illustrated in several examples. One of them justifies the title of this paper. We conjecture that these mechanisms are deeply related to the very frequent emergence, in natural and artificial complex systems, of scale-free structures and to their connections with nonextensive statistical mechanics. Summarizing, we have shown that, for asymptotically scale-invariant systems, it is S(q) with q not equal 1, and not S(BG), the entropy which matches standard, clausius-like, prescriptions of classical thermodynamics.
  • Yuzuru Sato, Eizo Akiyama, James P. Crutchfield
    Physica D: Nonlinear Phenomena 210 (1-2) 21 - 57 0167-2789 2005/10/01 [Refereed][Not invited]
     
    We derive a class of macroscopic differential equations that describe collective adaptation, starting from a discrete-time stochastic microscopic model. The behavior of each agent is a dynamic balance between adaptation that locally achieves the best action and memory loss that leads to randomized behavior. We show that, although individual agents interact with their environment and other agents in a purely self-interested way, macroscopic behavior can be interpreted as game dynamics. Application to several familiar, explicit game interactions shows that the adaptation dynamics exhibits a diversity of collective behaviors. The simplicity of the assumptions underlying the macroscopic equations suggests that these behaviors should be expected broadly in collective adaptation. We also analyze the adaptation dynamics from an information-theoretic viewpoint and discuss self-organization induced by the dynamics of uncertainty, giving a novel view of collective adaptation. (c) 2005 Elsevier B.V. All rights reserved.
  • Extensivity and entropy production
    Constantino Tsallis, Murray Gell-Mann, Yuzuru Sato
    Europhysics News 36 (6) 186 - 189 2005 [Refereed][Not invited]
  • Yuzuru Sato, Takashi Ikegami
    Minds and Machines 14 (2) 133 - 143 0924-6495 2004/05 [Refereed][Not invited]
     
    This paper considers undecidability in the imitation game, the so-called Turing Test. In the Turing Test, a human, a machine, and an interrogator are the players of the game. In our model of the Turing Test, the machine and the interrogator are formalized as Turing machines, allowing us to derive several impossibility results concerning the capabilities of the interrogator. The key issue is that the validity of the Turing test is not attributed to the capability of human or machine, but rather to the capability of the interrogator. In particular, it is shown that no Turing machine can be a perfect interrogator. We also discuss meta-imitation game and imitation game with analog interfaces where both the imitator and the interrogator are mimicked by continuous dynamical systems.
  • 多体学習のダイナミクス
    佐藤譲
    2000年4月号 76 - 82 2004 [Not refereed][Not invited]
  • Y Sato, JP Crutchfield
    PHYSICAL REVIEW E 67 (1) 015206  1539-3755 2003/01 [Refereed][Not invited]
     
    Starting with a group of reinforcement-learning agents we derive coupled replicator equations that describe the dynamics of collective learning in multiagent systems. We show that, although agents model their environment in a self-interested way without sharing knowledge, a game dynamics emerges naturally through environment-mediated interactions. An application to rock-scissors-paper game interactions shows that the collective learning dynamics exhibits a diversity of competitive and cooperative behaviors. These include quasiperiodicity, stable limit cycles, intermittency, and deterministic chaos-behaviors that should be expected in heterogeneous multiagent systems described by the general replicator equations we derive.
  • Yuzuru Sato, James P. Crutchfield
    Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 67 (1 2) 152061 - 152064 1063-651X 2003/01 [Refereed]
     
    Coupled replicator equations for the dynamics of learning in multiagent systems were presented. It was shown that a game dynamics emerges naturally through environment-mediated interactions. Rock-scissors-paper game interactions showed that the collective learning dynamics exhibits a diversity of competitive and cooperative behaviors.
  • Weaverのコミュニケーションの問題と情報理論
    佐藤譲
    統計数理研究所共同研究リポート 171 55 - 57 2003 [Not refereed][Not invited]
  • Y Sato, E Akiyama, JD Farmer
    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 99 (7) 4748 - 4751 0027-8424 2002/04 [Refereed][Not invited]
     
    We investigate the problem of learning to play the game of rock-paper-scissors. Each player attempts to improve her/his average score by adjusting the frequency of the three possible responses, using reinforcement learning. For the zero sum game the learning process displays Hamiltonian chaos. Thus, the learning trajectory can be simple or complex, depending on initial conditions. We also investigate the non-zero sum case and show that it can give rise to chaotic transients. This is, to our knowledge, the first demonstration of Hamiltonian chaos in learning a basic two-person game, extending earlier findings of chaotic attractors in dissipative systems. As we argue here, chaos provides an important self-consistency condition for determining when players will learn to behave as though they were fully rational. That chaos can occur in learning a simple game indicates one should use caution in assuming real people will learn to play a game according to a Nash equilibrium strategy.
  • 学習のダイナミクス
    佐藤譲
    統計数理研究所共同研究リポート 163 77 - 87 2002 [Not refereed][Not invited]
  • Y Sato, M Taiji, T Ikegami
    UNCONVENTIONAL MODELS OF COMPUTATION UMC' 2K, PROCEEDINGS 234 - 247 2001 [Refereed][Not invited]
     
    A dynamical systems based model of computation is studied, and we demonstrate the computational ability of nonlinear mappings. There exists a switching map system with two types of baker's map to emulate any Turing machine. The baker's maps correspond to the elementary operations of computing such as left/right shift and reading/writing of symbols in Turing machines. Taking other mappings with second-order nonlinearity (e.g. the Henon map) as elementary operations, the switching map system becomes an effective analog computer executing parallel computation similarly to MRAM. Our results show that, with bitwise Boolean AND, it has PSPACE computational power. Without bitwise Boolean AND, it is expected that its computational power is between classes RP and PSPACE. These dynamical systems execute more unstable computation than that of classical Turing machines, and this suggests a trade-off principle between stability of computation and computational power.
  • 計算のダイナミクス
    佐藤譲
    統計数理研究所共同研究リポート 144 1 - 8 2001 [Not refereed][Not invited]
  • OHIRA Toru, SATO Yuzuru
    Butsuri 一般社団法人日本物理学会 55 (5) 360 - 363 0029-0181 2000/05/05 
    「ノイズ」と通信や相互作用の「遅れ」は多くのシステムに存在し,複雑な挙動を引き起こす.ここではそのような複雑な挙動の理解への一つの方向として,ノイズと遅れを用いた共鳴現象を示す単純なモデルを紹介する.その性質を調べることにより,情報処理系において通常障害と考えられている「ノイズ」と「遅れ」を活用する方向を模索する.
  • R Ohira, Y Sato, JD Cowan
    ADVANCES IN NEURAL INFORMATION PROCESSING SYSTEMS 12 12 314 - 320 1049-5258 2000 [Refereed][Not invited]
     
    We study here a simple stochastic single neuron model with delayed self-feedback capable of generating spike trains. Simulations show that its spike trains exhibit resonant behavior between "noise" and "delay". In order to gain insight into this resonance, we simplify the model and study a stochastic binary element whose transition probability depends on its state at a fixed interval in the past. With this simplified model we can analytically compute interspike interval histograms, and show how the resonance between noise and delay arises. The resonance is also observed when such elements are coupled through delayed interaction.
  • Yuzuru Sato, Takashi Ikegami
    J. UCS 6 (9) 881 - 905 2000 [Refereed][Not invited]
  • Computation with switching map systems
    Yuzuru Sato, Takashi Ikegami
    Journal of Universal Computer Sciences Vol. 6 (No. 9) 881-894  2000 [Refereed][Not invited]
  • Y Sato, M Taiji, T Ikegami
    COMPUTER PHYSICS COMMUNICATIONS 121 51 - 53 0010-4655 1999/09 [Refereed][Not invited]
     
    The geometrical structure of a formal language class is studied in relation with its time-complexity. A typical NP-complete problem, kSAT, is discussed by visualizing its problem space and a strict connection is made between the self-similarity and the time-complexity of the languages by constructing adequate iterated function systems (IFSs), There exist IFS classes which generate whole satisfiable Boolean expressions embedded on a unit hyper-cube, Our numerical results for the Hausdorff dimension of kSAT suggest the difference of IFS classes for 2 and 3SAT. (C) 1999 Elsevier Science B.V. All rights reserved.
  • Toru Ohira, Yuzuru Sato
    Physical Review Letters 82 (14) 2811 - 2815 1079-7114 1999 [Refereed][Not invited]
     
    We propose here a stochastic binary element whose transition rate depends on its state at a fixed interval in the past. With this delayed stochastic transition this is one of the simplest dynamical models under the influence of “noise” and “delay.” We demonstrate numerically and analytically that we can observe resonant phenomena between the oscillatory behavior due to noise and that due to delay. © 1999 The American Physical Society.
  • Undecidability of the Imitation Game
    Yuzuru Sato, Takashi Ikegami
    Proceedings of Symposium on Imitation in Animals and Artifacts 157 - 159 1999 [Refereed][Not invited]
  • Y Sato, M Taiji, T Ikegami
    UNCONVENTIONAL MODELS OF COMPUTATION 352 - 370 1998 [Refereed][Not invited]
     
    Recursive operations are common procedures in the fields of computational theory and fractal geometry. Recently, computational theory has paid much attention to fractal geometry. In this paper, the geometrical structure of a formal language class is studied in relation with its time-complexity. A typical NP-complete problem, kSAT, is discussed by visualizing its problem space. A strict connection is made between the self-similarity and the time-complexity of the languages by constructing adequate iterated function systems (IFSs). There exist IFS classes which generate whole satisfiable Boolean expressions embedded on a unit hyper-cube. The difference in time-complexity between 2SAT and 3SAT is connected to IFS classes which generate satisfiable Boolean expressions. That is, the class P complexity is related to what we call monotone IFS and the class NP or upper complexity does to more complex IFS. Our numerical results for the Hausdorff dimension of satisfiable Boolean expressions suggest the difference of IFS classes between 2 and 3SAT.

MISC

  • Yuzuru Sato, Daiji Tsutsui, Akio Fujiwara  PHYSICA D-NONLINEAR PHENOMENA  430-  2022/02  
    In order to elucidate the plateau phenomena caused by vanishing gradient, we herein analyse stability of stochastic gradient descent near degenerated subspaces in a multi-layer perceptron. In stochastic gradient descent for Fukumizu-Amari model, which is the minimal multi-layer perceptron showing non-trivial plateau phenomena, we show that (1) attracting regions exist in multiply degenerated subspaces, (2) a strong plateau phenomenon emerges as a noise-induced synchronisation, which is not observed in deterministic gradient descent, (3) an optimal fluctuation exists to minimise the escape time from the degenerated subspace. The noise-induced degeneration observed herein is expected to be found in a broad class of machine learning via neural networks.
  • Takumi Chihara, Yuzuru Sato, Isaia Nisoli, Stefano Galatolo  CHAOS  32-  (1)  2022/01/01  
    We prove the existence of multiple noise-induced transitions in the Lasota-Mackey mapl, which is a class of one-dimensional random dynamical system with additive noise. The result is achieved by rigorous computer assisted estimates. We first approximate the stationary distribution of the random dynamical system and then compute certifiederror intervals for the Lyapunov exponent. We find that the signs of the Lyapunov exponents changes at least three times when increasing the noise amplitude. We also show numerical evidence that the standard non-rigorous numericalapproximation by finite-time Lyapunov exponents is valid with our model for a sufficiently large number of iterations.Our method is expected to work for a broad class of nonlinear stochastic p
  • 佐藤譲  日本応用数理学会年会講演予稿集(CD-ROM)  2019-  487  2019/08/21  [Not refereed][Not invited]
  • Yuzuru Sato, Kathrin Padberg-Gehle  2019/05/08  [Not refereed][Not invited]
     
    Noise-induced statistical periodicity in a class of one-dimensional maps is
    studied. We show the existence of statistical periodicity in a modified
    Lasota-Mackey map and describe the phenomenon in terms of almost cyclic sets. A
    transition from a stable state to a periodic state of the density depending on
    the noise level is observed in numerical investigations based on trajectory
    averages and by means of a transfer operator approach. We conclude that the
    statistical periodicity is the origin of the almost periodicity in
    noise-induced order.
  • Yuzuru Sato, Thai Son Doan, Jeroen S, W. Lamb, Martin Rasmussen  2018/11/10  [Not refereed][Not invited]
     
    The emergence of noise-induced chaos in a random logistic map with bounded
    noise is understood as a two-step process consisting of a topological
    bifurcation flagged by a zero-crossing point of the supremum of the dichotomy
    spectrum and a subsequent dynamical bifurcation to a random strange attractor
    flagged by a zero crossing point of the Lyapunov exponent. The associated three
    consecutive dynamical phases are characterized as a random periodic attractor,
    a random point attractor, and a random strange attractor, respectively. The
    first phase has a negative dichotomy spectrum reflecting uniform attraction to
    the random periodic attractor. The second phase no longer has a negative
    dichotomy spectrum - and the random point attractor is not uniformly attractive
    - but it retains a negative Lyapunov exponent reflecting the aggregate
    asymptotic contractive behaviour. For practical purposes, the extrema of the
    dichotomy spectrum equal that of the support of the spectrum of the finite-time
    Lyapunov exponents. We present detailed numerical results from various
    dynamical viewpoints, illustrating the dynamical characterisation of the three
    different phases.
  • Sato Yuzuru  RIMS Kokyuroku  1827-  24  -32  2013/03
  • Sato Yuzuru  Meeting abstracts of the Physical Society of Japan  67-  (1)  381  -381  2012/03/05
  • Sato Yuzuru  Meeting abstracts of the Physical Society of Japan  65-  (1)  351  -351  2010/03/01
  • SATO Yuzuru  高温学会誌  33-  (3)  3  -4  2007/05/23
  • SATO Yuzuru  Journal of High Temperature Society.  32-  (5)  260  -267  2006/09/25
  • SATO Y.  Japan journal of thermophysical properties  16-  (1)  34  -37  2002/01/31
  • SATO Y.  熱物性 : Japan journal of thermophysical properties  15-  (1)  8  -8  2001/01/31
  • SATO Y.  熱物性 : Japan journal of thermophysical properties  13-  (4)  321  -321  1999/10/31

Books etc

Presentations

  • Stochastic bifurcation in a turbulent swirling flow  [Invited]
    Yuzuru Sato
    17th Japan-Slovenia Seminar on Nonlinear Science  2022/03
  • Stochastic bifurcation in a turbulent swirling flow  [Not invited]
    Yuzuru Sato
    Dynamical systems and its applications  2022/02
  • Existence of multiple noise-induced transitions in Lasota-Mackey map  [Invited]
    Yuzuru Sato
    Hokkaido Summer Institute on Computational Ergodic Theory  2021/09
  • Stochastic bifurcation in a turbulent swirling flow  [Invited]
    Yuzuru Sato
    Mathematical methods for the studies of flow, shape, and dynamics  2021/08
  • Stochastic bifurcation in a turbulent swirling flow  [Not invited]
    Yuzuru Sato
    RIMS workshop on dynamical systems  2021/06
  • Stochastic chaos in random dynamical systems and its applications  [Invited]
    Yuzuru Sato
    Mathematical Science of Complex Systems: Physics, Chemistry, Biology, Information and Chaos  2021/03
  • Noise-induced degeneration in online learning  [Not invited]
    Yuzuru Sato
    Dynamical systems and machine learning  2020/09
  • Stochastic bifurcation in a turbulent swirling flow  [Invited]
    Yuzuru Sato
    CRITICS workshop 2020  2020/08
  • Stochastic bifurcation and intermittency in random dynamical systems  [Invited]
    Yuzuru Sato
    RIMS workshop  2019/10
  • Anomalous diffusion in random dynamical systems  [Invited]
    Yuzuru Sato
    The Mathematics of Climate and Environment, IHP  2019/10
  • Anomalous diffusion and intermittency in deterministic /random dynamical systems  [Not invited]
    Yuzuru Sato
    RIMS workshop  2019/09
  • Stochastic bifurcation in a turbulent swirling flow  [Not invited]
    Yuzuru Sato
    JSIAM  2019/09
  • Anomalous diffusion and intermittency in random dynamical systems  [Not invited]
    Yuzuru Sato
    Seminar at Tokyo Metropolitan University,  2019/09
  • Noise-induced Statistical Periodicity in Lasota-Mackey Maps  [Not invited]
    Yuzuru Sato
    RIMS workshop  2019/08
  • Anomalous diffusion in random dynamical systems  [Invited]
    Yuzuru Sato
    DCP19  2019/07
  • Stochastic bifurcation in a turbulent swirling flow  [Invited]
    Yuzuru Sato
    ICIAM  2019/07
  • Stochastic bifurcation in a turbulent swirling flow  [Not invited]
    Yuzuru Sato
    RIMS workshop  2019/06
  • Stochastic bifurcation in a turbulent swirling flow  [Not invited]
    Yuzuru Sato
    Workshop on data analysis and machinelearning in dynamical systems  2019/05
  • Stochastic bifurcation in a turbulent swirling flow  [Invited]
    Yuzuru Sato
    CRITICS workshop, Imperial College London  2019/03
  • Stochastic chaos in random dynamical systems and its application to time series analysis  [Invited]
    Yuzuru Sato
    Seminar at University of Pisa  2018/10
  • Stochastic bifurcation in random dynamical systems and its application to modeling atmospheric jet dynamics  [Invited]
    Yuzuru Sato
    “Dynamical Systems and Climate Dynamics,” LSCE/CNRS-Saclay  2018/10
  • Stochastic bifurcation in random logistic map  [Not invited]
    Yuzuru Sato
    Dynamics Days Europe  2018/09
  • Stochastic chaos in a turbulent swirling flow  [Invited]
    Yuzuru Sato
    LML summer school, London Mathematical Laboratory  2018/08
  • Stochastic chaos in a turbulent swirling flow  [Not invited]
    Yuzuru Sato
    MIMS seminar  2018/07
  • Stochastic chaos in a turbulent swirling flow  [Invited]
    Yuzuru Sato
    CIMPA spring school, Vietnam Academy of Science and Technology  2018/03
  • Stochastic chaos in a turbulent swirling flow  [Invited]
    Yuzuru Sato
    Lorentz Center Workshop on Random Dynamical Systems  2017/12
  • Anomalous diffusion and intermittency in random dynamical systems  [Invited]
    Yuzuru Sato
    Statistical and nonlinear physics seminar at CNRS  2017/11
  • Stochastic bifurcation and early warning signals in random logistic maps  [Not invited]
    Yuzuru Sato
    Predicting extremes in climate dynamics  2017/10
  • Anomalous diffusion and intermittency in random dynamical systems  [Not invited]
    Yuzuru Sato
    workshop on nonlinearity and complexity  2017/09
  • Anomalous diffusion and intermittency in random dynamical systems  [Invited]
    Yuzuru Sato
    ANOCOS, Tempare, Finland  2017/08
  • Anomalous diffusion and intermittency in random dynamical systems  [Not invited]
    Yuzuru Sato
    seminar at Tokyo Metroplitan University  2017/06
  • Stochastic chaos in a turbulent swirling flow  [Not invited]
    Yuzuru Sato
    RIMS workshop  2017/06
  • Crutchfield-Shaw information theory for noisy chaos: a review  [Not invited]
    Yuzuru Sato
    RIMS workshop  2017/06
  • Stochastic bifurcation in random logistic maps  [Invited]
    Yuzuru Sato
    SIAM Conference on Applications of Dynamical systems  2017/05
  • Anomalous diffusion and intermittency in random dynamical systems  [Invited]
    Yuzuru Sato
    Kyoto Dynamics Days: Random Dynamical Systems Theory and Its Applications, Kyoto University  2017/04
  • Noise-induced bifurcations in a random logistic map  [Invited]
    Yuzuru Sato
    Kyoto Dynamics Days: Random Dynamical Systems Theory and Its Applications, Kyoto University  2017/04
  • Anomalous diffusion and intermittency in random dynamical systems  [Not invited]
    Yuzuru Sato
    JSIAM  2017/03
  • Stochastic bifurcation in random logistic maps  [Not invited]
    Yuzuru Sato
    Keno Dynamics Days  2017/01
  • Stochastic bifurcation in random logistic maps  [Invited]
    Yuzuru Sato
    Applications of statical-mechanics and dynamical systems to climate, LSCE, CEA, CNRS  2016/11
  • Anomalous diffusion in random dynamical systems,  [Invited]
    Yuzuru Sato
    Dynamics Days Latin America and the Caribbean, University of Puebla  2016/10
  • Anomalous diffusion in random dynamical systems,  [Invited]
    Yuzuru Sato
    Hokkaido-Pisa Summer Institute, University of Pisa  2016/09
  • Anomalous diffusion in random dynamical systems,  [Invited]
    Yuzuru Sato
    Workshop on Anomalous Dynamics and Weak ergodicity breaking, University of Warwick  2016/08
  • Chaos in function dynamics  [Invited]
    Yuzuru Sato
    RIMS workshop  2016/07
  • Noise-induced statistical periodicity and almost cyclic sets  [Not invited]
    Yuzuru Sato
    RIMS workshop  2016/06
  • Anomalous diffusion in random dynamical systems  [Not invited]
    Yuzuru Sato
    Workshop on dynamical systems and computation  2016/03
  • Neural Field dynamics for growing brains  [Invited]
    Yuzuru Sato
    AAAS panel presentation, AAAS  2016/02
  • Robust computation in neural field  [Invited]
    Yuzuru Sato
    AFCA keynote talk, CANDAR  2015/12
  • Robust pattern construction in neural field  [Not invited]
    Yuzuru Sato
    seminar at Kyoto University  2015/11
  • Chaos in random and non-autonomous dynamical systems  [Invited]
    Yuzuru Sato
    Complex systems summer school  2015/07
  • Dynamics of Neural Field  [Invited]
    Yuzuru Sato
    Seminar at University of Tokyo  2015/03
  • Random strange attractors and stochastic chaos  [Invited]
    Yuzuru Sato
    Workshop on dynamical systems and computation  2015/03
  • Random Strange Attractors and Stochastic Chaos  [Not invited]
    Yuzuru Sato
    Dynamical Systems and Computation, Sapporo  2015/02
  • Random dynamical systems approaches to noise-induced phenomena  [Invited]
    Yuzuru Sato
    Seminar at University of Sussex Brighton UK  2014/11
  • Random dynamical systems approaches to noise-induced phenomena  [Invited]
    Yuzuru Sato
    Max Planck Institute, Dynamics and Self-organization  2014/10
  • Random basin in dice roll  [Invited]
    Yuzuru Sato
    Workshop on Theory and Applications of Random/Nonautonomous Dynamical Systems  2014/09
  • Asymmetric game dynamics and its applications  [Invited]
    Yuzuru Sato
    SAET  2014/08
  • Random dynamical systems approaches to noise-induced phenomena  [Invited]
    Yuzuru Sato
    Workshop on Computation and Computability in Dynamics, Trieste  2014/07
  • Random dynamics from time seiries of rotating fluids  [Not invited]
    Yuzuru Sato
    Workshop on Physical Origins of Correlated Extreme Events  2014/06
  • Random dynamical systems approaches to noise-induced phenomena  [Invited]
    Yuzuru Sato
    Seminar at Loughborough University Loughborough  2014/05
  • Random dynamical systems approaches to noise-induced phenomena  [Invited]
    Yuzuru Sato
    Mini Conference on Glassy and Complex Systems  2014/05
  • Random dynamical systems approaches to noise-induced phenomena  [Not invited]
    Yuzuru Sato
    Open Statistical Physics  2014/03
  • Random dynamical systems approaches to noise-induced phenomena  [Invited]
    Yuzuru Sato
    Dynamical Systems, Fluid Dynamics and Lagrangian Coherent Structures  2014/03
  • Random dynamical systems approaches to noise-induced phenomena  [Invited]
    Yuzuru Sato
    ランダム力学系理論とその応用 京都府京都市  2014/02
  • Random basin in dice roll  [Invited]
    Yuzuru Sato
    ランダム力学系理論とその応用  2014/02
  • Stability and diversity in collective adaptation  [Invited]
    Yuzuru Sato
    Seminar at Manchester University  2014/02
  • Real number computation and dynamical systems  [Invited]
    Yuzuru Sato
    Dynamical systems and computation  2014/01
  • Random dynamics from time series  [Invited]
    Yuzuru Sato
    SIAM Conference on Applications of Dynamical systems  2013/05
  • Noise-induced phenomena in one-dimensional maps  [Invited]
    Yuzuru Sato
    Seminar at Hitotsubashi University  2013/04
  • Asymmetric game dynamics and its applications  [Invited]
    Yuzuru Sato
    Seminar at King’s College London  2013/04
  • Randomness in noised dynamical systems  [Invited]
    Yuzuru Sato
    Ergodic theory, information theory and computer sciences  2013/04
  • Partial Control of Chaos and Continuity of Safe Sets  [Not invited]
    G. Wang, Y. Sato
    Dynamics Days US  2013/01
  • Randomness of Perturbed Dice Throw Dynamics  [Not invited]
    N. Matsunaga, Y. Sato
    Dynamics Days US  2013/01
  • Random Dynamics from a Time Series of Physiological Rhythms  [Invited]
    Yuzuru Sato
    NOLTA2012  2012/10
  • Asymmetric game dynamics and its applications  [Invited]
    Yuzuru Sato
    CICS Colloquium, Universidad del Desarrollo  2012/10
  • Random dynamical systems approaches to noise-induced phenomena  [Invited]
    Yuzuru Sato
    Summer Workshop on Artificial Minds and Real Brains  2012/08
  • Noise-induced phenomena and their applications  [Invited]
    Yuzuru Sato
    Workshop on Open dynamical systems: Ergodic Theory, Probabilistic Methods and Applications, BIRS Banff Canada  2012/04
  • Noise-induced phenomena in one dimensional maps  [Invited]
    Yuzuru Sato
    Seminar at Soongsil University Seoul, Korea  2012/04
  • Noise-induced phenomena and their applications: interaction between deterministic chaos and stochastic randomness  [Invited]
    Yuzuru Sato
    Nonlinear Science Colloquium at Waseda University  2012/04
  • Noise-induced phenomena and their applications: interaction between deterministic chaos and stochastic randomness  [Invited]
    Yuzuru Sato
    International workshop on Anomalous Statistics, Generalized Entropies, and Information Geometry  2012/03
  • Random dynamics from time-series and its applications  [Invited]
    Yuzuru Sato
    NOLTA2011  2011/09
  • Noise-induced phenomena in one-dimensional maps  [Not invited]
    Yuzuru Sato
    Weak Chaos, Infinite Ergodic Theory, and Anomalous Dynamics  2011/08
  • Noise-induced phenomena in one dimensional maps  [Invited]
    Yuzuru Sato
    Kyoto interdisciplinary Dynamics Seminar  2011/07
  • Robust Computation in Two-dimensional Neural Field  [Invited]
    Yuzuru Sato
    The 3rd International Conference on Cognitive Neurodynamics  2011/06
  • Noise-induced phenomena in one dimensional maps  [Invited]
    Yuzuru Sato
    SIAM Conference on Applications of Dynamical systems  2011/05
  • Asymmetric game dynamics and its extensions  [Invited]
    Yuzuru Sato
    Game theory workshop, Nagoya  2011/05
  • Random nonlinear phenomena and its applications  [Invited]
    Yuzuru Sato
    Yakushima Workshop  2011/04
  • Noise-induced phenomena in one dimensional maps  [Invited]
    Yuzuru Sato
    Seminar at Department of Applied Mathematics at the University of Colorado at Boulder  2011/04
  • Asymmetric game dynamics and its extensions  [Not invited]
    Yuzuru Sato
    Game theory workshop  2011/03
  • Noise-induced statistical periodicity and its applications  [Invited]
    Yuzuru Sato
    Dynamics of Complex Systems  2011/03
  • 回転流体系における自由表面の不規則スイッチング現象の決定論性の推定  [Not invited]
    飯島 悠宇, 田坂 裕司, 佐藤 讓, 飯間 信
    2010年度応用数学合同研究集会  2010/12
  • Noise-induced phenomena in one dimensional maps  [Invited]
    Yuzuru Sato
    NIMS Hot Topics Workshop on Applied Dynamical Systems  2010/12
  • Noise-induced phenomena in one dimensional maps  [Invited]
    Yuzuru Sato
    Max-Planck Institute, Mathematics in the Sciences  2010/12
  • Noise-induced phenomena in one dimensional maps  [Invited]
    Yuzuru Sato
    Kagoshima workshop on nonlinear and Nonequilibrium dynamics  2010/10
  • Noise-induced phenomena in one dimensional maps  [Invited]
    Yuzuru Sato
    RIKEN Mathematical Science Workshop  2010/09
  • Robust computation in activation-inhibition field  [Invited]
    Yuzuru Sato
    The 9th international conference on unconventional computation  2010/06
  • Noise-induced phenomena in one dimensional maps  [Invited]
    Yuzuru Sato
    Niseko workshop on mathematical biology  2010/04
  • Noise-induced phenomena in one dimensional maps  [Not invited]
    Yuzuru Sato
    日本物理学会  2010/03
  • Noise-induced phenomena in one dimensional maps: hidden fragility in nonlinear dynamics  [Invited]
    Yuzuru Sato
    Sapporo winter school on nonlinear science  2010/02
  • Noise-induced phenomena in one dimensional maps  [Invited]
    Yuzuru Sato
    NIMS Hot Topics, Workshop on Applied Dynamical Systems “Dynamics in Network and Mathematical Neuroscience,” NIMS  2010/02
  • Stability and diversity in collective adaptation  [Invited]
    Yuzuru Sato
    Chaos revolution in Science  2009/12
  • Statistics and dynamical analysis of surface switching in rotating fluid  [Not invited]
    Y. Tasaka, M. Iima, Y. Sato
    16th International Couette-Taylor Workshop Princeton  2009/09
  • Noise-induced phenomena in one dimensional maps  [Invited]
    Yuzuru Sato
    Dynamics of Complex Systems  2009/08
  • Noise-induced phenomena in one dimensional maps  [Invited]
    Yuzuru Sato
    Biology and Control, SICE  2009/05
  • Noise-induced phenomena in one dimensional maps  [Invited]
    Yuzuru Sato
    Behavior and Logic of Cellular Systems, RIKEN  2009/04
  • High-dimensional chaotic dynamics in an N-person game  [Invited]
    Yuzuru Sato
    Seminar at Kyushu University  2009/04
  • Noise-induced phenomena in one dimensional maps  [Invited]
    Yuzuru Sato
    Workshop: Fluctuation and Noise in Living Organisms, RIKEN  2009/04
  • Chaos in function dynamics  [Invited]
    Yuzuru Sato
    Seminar at GCOE workshop, Kobe University  2009/04
  • Random Dynamics from Time Serieses of Rotating Fluid  [Not invited]
    Yuzuru Sato
    応用数理学会  2008/09
  • Random Dynamics from Time Serieses of Rotating Fluid  [Invited]
    Yuzuru Sato
    ynamics Days Asia-Pacific  2008/09
  • Random Dynamics from Time Serieses of Rotating Fluid  [Invited]
    Yuzuru Sato
    Dynamics of Complex systems  2008/09
  • Limit of Analog Computation  [Invited]
    Yuzuru Sato
    Seminar at University of Tokyo  2008/04
  • Re-visiting Noise-induced Order  [Not invited]
    Yuzuru Sato
    Artificial Life: Half-way through  2008/04
  • Noise-induced Phenomena in one-dimensional maps  [Not invited]
    Yuzuru Sato
    Seminar at ASI, RIKEN  2008/04
  • Function Dynamics: An Introductory Review  [Not invited]
    Yuzuru Sato
    動的システムの情報論VII  2007/11
  • Heteroclinic Cycles in N-person Game Dynamics  [Invited]
    Yuzuru Sato
    inisymposium at SIAM Conference on Application of Dynamical Systems Snowbird, Utah USA  2007/05
  • N-person Game Dynamics  [Invited]
    Yuzuru Sato
    Seminar at Santa Fe Institute  2007/04
  • Stability and Diversity in Collective Adaptation  [Not invited]
    Yuzuru Sato
    Seminar at Department of Physical Chemistry Fritz Haber Institute  2006/04
  • Stability and Diversity in Collective Adaptation  [Invited]
    Yuzuru Sato
    Long-term workshop at Isaac Newton Institute, Cambridge, England, UK  2005/09
  • patiotemporal Intermittency and its Application to Problems of Memory and Learning  [Invited]
    Yuzuru Sato
    Seminar at JAIST  2005
  • Dynamics of learning in Rock-Scissors-Paper game  [Invited]
    Yuzuru Sato
    Seminar at KNU Daegu, Korea  2005
  • Spatiotemporal Intermittency and its Application to Problems of Memory and Learning  [Invited]
    Yuzuru Sato
    Seminar at Santa Fe Institute, Santa Fe, New Mexico, USA  2005
  • Stability and Diversity in Collective Adaptation  [Invited]
    Yuzuru Sato
    Seminar at Santa Fe Institute, Santa Fe, New Mexico, USA  2004
  • Dynamics of Learning and Flows of Information in Collectives  [Invited]
    Yuzuru Sato
    Dynamics Days Europe XXIII, Palma de Mallorca, Spain  2003/09
  • Dynamics of Analog Computation  [Invited]
    Yuzuru Sato
    Philosophy of Computation  2003
  • Dynamics of coupled replicator equations  [Not invited]
    Yuzuru Sato
    "Dynamics Days Europe XXII", Heiderberg, Germany  2002/07
  • Dynamics of learning and coupled replicator  [Invited]
    Yuzuru Sato
    Workshop on Dynamical Systems in Mathematical Biology, Tokyo, Japan  2002/05
  • Coupled replicator equations for the dynamics of learning in multiagent systems  [Invited]
    Yuzuru Sato
    Seminar at Research Unit in Language Evolution and Computation, University of Edinburgh  2002
  • Computation with switching map systems: Nonlinearity and computational complexity  [Invited]
    Yuzuru Sato
    Seminar at Department of Applied Mathematics, Princeton University Princeton, NJ, USA  2001
  • NP-completeness of kSAT and multifractals  [Not invited]
    Yuzuru Sato
    Conference on Computational Physics, Granada, Spain  1998/09

Teaching Experience

  • Seminar on numerical computationSeminar on numerical computation Chitose Institute of Science and Technology
  • Seminar on geometrySeminar on geometry
  • Geometry IGeometry I Chitose Institute of Science and Technology

Association Memberships

  • Society for Industrial and Applied Mathematics   American Physical Society   日本応用数理学会   日本物理学会   日本数学会   

Research Projects

  • 日本学術振興会：科学研究費助成事業
    Date (from‐to) : 2024/04 -2029/03 
    Author : 角 大輝, 佐藤 譲, 上原 崇人, 渡邉 天鵬, 井上 友喜, 矢野 孝次, イェーリッシュ ヨハネス
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2021/04 -2026/03 
    Author : 佐藤 譲, 角 大輝, 矢野 孝次
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    Date (from‐to) : 2019/04 -2024/03 
    Author : 角 大輝, 中西 敏浩, 佐藤 譲, 上原 崇人, 諸澤 俊介, 和田 昌昭, イェーリッシュ ヨハネス
     
    角はランダム複素力学系の研究を行った。特にシステムの写像らが共通固定点を持つ複雑なランダム複素力学系についても、そのようなシステムのほとんどのものは弱平均安定性を持ちシステムのカオス性が著しく軽減することを示した。その応用として、「ランダム緩和ニュートン法」を考えると、従来の決定論的ニュートン法と比べて多項式の根をある意味で見つけやすくなることを示した。また、マルコフ的ランダム複素力学系の平均安定性や、非有界多項式列のジュリア集合の非一様不完全性を調べた。また、角とイエーリッシュは、実直線上の拡大的写像のランダム力学系を調べ、推移作用素のスペクトルギャップ性を示し、無限遠点に収束する確率の関数やその確率パラメータに関する偏微分の各点ヘルダー指数についてのマルチフラクタル解析を行った。 佐藤はランダム力学系における新たな間欠性と異常拡散を発見したほか、ランダム力学系理論をジェット気流の時系列解析、機械学習の停滞現象の解析、感染症モデルの解析に応用し、また、雑音誘起現象の存在に関する計算機援用証明を行った。 中西は有限次元タイヒミュラー空間とその上に作用する写像類群に関する研究を行った。特に2つ穴あきトーラスと種数2の閉曲面のタイヒミュラー空間の元である曲面群のSL(2,R)表現の行列表示を具体的に与え写像類群を有理写像のつくる群として具体的に実現した。上原は特定のクラスの複素曲面の構成およびその上の双有理自己同型写像による力学系の解析を行なった. 有理曲面を用いてK3曲面を構成し複素曲面上の力学系の複雑さを表すエントロピーについて考察した。 諸澤は超越整関数の半群の力学系の研究を行なった。特に超越整関数の内側合成の研究を行なった。和田はフラクタル幾何学研究支援プログラムであるFractal Gazerを開発し、それを用いて３つの相似変換による相似タイリングを多数発見した。
  • ランダムな実および複素力学系、正則写像半群とフラクタル幾何学の研究
    文部科学省：科学研究費補助金(基盤研究(B))
    Date (from‐to) : 2019 -2023 
    Author : 角 大輝
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Exploratory)
    Date (from‐to) : 2019/06 -2022/03 
    Author : 矢野 孝次, 佐藤 譲, 角 大輝, 中野 雄史
     
    一般化逆正弦法則の発展的問題として，秋元（東京理科大学）および大学院生の世良と山戸と共同で，エイジングの問題に取り組み始めた．原点出発のブラウン運動の滞在時間分布は逆正弦法則と呼ばれるが，その一般化として歪ベッセル過程の滞在時間分布はランペルティ分布に従うことがよく知られている．これらの結果は出発時点から観測を開始したときのものであるが，観測開始時間を零から正に変えたときどのような影響が現れるかを調べるのがエイジングの問題である．ブラウン運動および歪ベッセル過程に対して詳しく調べ，理論物理的視点でまとめた結果を投稿するに至った． 作用発展に対する情報系分解問題について，伊藤（京都産業大学）および大学院生の世良と共同で，有限集合上のランダム写像反復モデルに対して一般的な結果をまとめることができた．有限集合を状態空間とし，ランダム写像反復による作用発展を考えるとき，一粒子のノイズには駆動ノイズと無限過去ノイズの他に第三ノイズが生ずることが分かっていたが，これらのノイズを成分としてどのように構成されているかは不明であった．本研究では多粒子のノイズを観測することによりこの問題を解決した．リース分解を用いた半群上のランダム変数の無限積に関する既知の一般的結果に基づき，情報系の結合演算の厳密な取り扱いに注意を払いながら，作用発展の情報系を，駆動ノイズ，無限過去ノイズ，第三ノイズに分解する公式を得ることができた．この結果は投稿に向けて準備中である．
  • 日本学術振興会：科学研究費助成事業 基盤研究(B)
    Date (from‐to) : 2017/04 -2022/03 
    Author : 藤原 彰夫, 佐藤 譲, 杉田 洋, 長岡 浩司, 山形 浩一
     
    確率分布空間の微分幾何構造の研究に源を発する情報幾何学は，様々な分野で応用され成功を収めてきたが，その理論体系自体は未だ発展途上であり，重要な未解決問題が数多く残されている．本研究では，量子局所漸近正規性に係わる情報幾何構造の研究，およびランダム力学系に内在する情報幾何構造の研究を２本の柱として位置づけ，研究を推進する．またこれと並行して，従来の情報幾何学では扱われなかった新規な研究対象を発掘し応用する．そして，こうした研究を通じ，統計数学における幾何学的方法の体系化を目指す． 本年度は，情報幾何学の新規な研究対象の発掘を目的として，量子情報科学において標準的に用いられている観測技術の一つである量子トモグラフィの情報幾何構造について研究した．d次元量子系の表現空間が相互不偏性条件を満たす(d+1)組の正規直交基底を持つと仮定する．このとき，各正規直交基底が生成する射影的測定をランダムに混合した測定を，ランダム量子トモグラフィーという．本研究ではまず，相互不偏基底全体が量子状態空間の基底をなし，それに対応する展開係数（仮にξとする）とランダム化の比率（仮にsとする）を統合した実数の組(ξ,s)が，測定結果の確率分布を表すd(d+1)次元ベクトル全体空間Pの座標系をなすこと，ξを固定したe-自己平行部分多様体E(ξ)と，sを固定したm-自己平行部分多様体M(s)は，標準Fisher計量に関するPの直交葉層化を与えることを示した．さらに，測定値から最尤推定値を求める操作は，標準Fisher計量に関する単純なm-射影ではなく，測定値に対応する経験分布が属する葉 M(s)ごとに定まる変形Fisher計量に基づくm-射影となることを明らかにした．本研究は，数学的に新規な情報幾何構造を明らかにしただけでなく，実験現場において最尤推定値を高速に計算するアルゴリズムも与えるものである．
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2018/04 -2021/03 
    Author : Sato Yuzuru
     
    Based on experimental time series analysis and modeling for large scale nonlinear phenomena, we quantitatively studied physical properties of stochastic chaos and contribute to studies on nonlinear stochastic phenomena systematically. Integrating former studies on noise-induced phenomena, we produce a phenomenology on noise-induced phenomena and apply it to real physical systems. The achieved results is as follows. (1) Expanding knowledge on noise-induced phenomena and stochastic bifurcation and give a computer-assisted proof on multiple noise-induced transitions. (2) We found stochastic chaos in fluid flow turbulence and climate dynamics through experimental time series analysis and modeling. (3) Random dynamical system approaches to machine learning and other algorithms and their concrete applications are shown.
  • 確率過程論的アプローチによるランダム力学系の理論研究
    文部科学省：挑戦的研究(萌芽)
    Date (from‐to) : 2019 -2021 
    Author : 矢野孝次
  • 古典および量子統計的システムにおける新規な情報幾何構造の探究
    文部科学省：科学研究費補助金(基盤研究(B))
    Date (from‐to) : 2017 -2021 
    Author : 藤原彰夫
  • ランダム力学系理論に基づく確率カオスの現象論とその応用
    文部科学省：科学研究費補助金(基盤研究(C))
    Date (from‐to) : 2018 -2020 
    Author : 佐藤譲
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (S)
    Date (from‐to) : 2014/05 -2019/03 
    Author : Taga Gentaro, WATANABE hama, SAJI ryoya
     
    We aimed to elucidate the dynamics of early development from morphogenesis of human brain to action generation. Three-dimensional information of the brain was extracted from MR microscopic images, CT images and serial tissue section images of embryos and fetal specimens to clarify basic phenomena of morphogenesis. We found an index named hPod that shows the development of blood oxygenation dynamics and the spontaneous activity of the brain in the fNIRS measurements of newborns and infants. fNIRS and EEG measurements with infants also revealed the basic properties of functional networks and sensory processing that change with sleep or awakening states. We proposed theoretical frameworks and models to understand the origin of spontaneous brain activity, co-dependent development of neural activity and cortical folding, and hybrid dynamics of reaction-diffusion systems and neural networks.
  • ヒト脳の形態形成から行動生成に至る発達のダイナミクス
    文部科学省：科学研究費補助金(基盤研究(S))
    Date (from‐to) : 2014 -2019 
    Author : 多賀 厳太郎
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for JSPS Fellows
    Date (from‐to) : 2015/11 -2018/03 
    Author : 佐藤 譲, DOAN THAI SON
     
    ノイズと決定論的力学の相互作用に伴う雑音誘起現象は非線形物理学では古くから研究されてきた問題です。雑音誘起現象とは、決定論力学系の自然測度が微小ノイズにより大幅に変化し、決定論極限で観測されなかった非線形現象がノイズ存在下で観測されるようになる現象です。よく知られた雑音誘起現象である確率共鳴、ノイズ同期、雑音誘起カオスは、いずれも緩急のついた運動を引き起こす不変多様体や、カオティックサドルといった不変集合と外部ノイズとの相互作用により生じます。とくに決定論的動力学がカオス的、あるいは潜在的にカオス的である場合、非自明な確率分岐現象が生じることが知られています。本研究の目的は非線形ランダム力学系の数値解析法を開発するとともに、ランダムlogistic写像、確率Lorenz系における確率分岐構造を解析し、確率カオスの現象論を構築することにあります。本年度は特にランダムlogistic写像における確率分岐、および確率位相方程式におけるノイズ同期現象を研究しました。本研究費(繰り越し分)に基づいて、2017年4月24日-28日に京都大学において、国際研究会Kyoto Dynamics Days: Random Dynamical Systems Theory and Its Applicationsを主催し、佐藤譲とThai Son Doanが参加講演しました。Jeroen Lamb, Martin Rasmussen, Maxi Angel (Imperial College London)、Ale Jan Homburg(University of Amsterdam)らを招聘し、ランダム力学系に関する総合的な共同研究を開始しました。
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
    Date (from‐to) : 2014/04 -2018/03 
    Author : YANO Kouji, NOBA Kei, YAMAZAKI Kazutoshi, YANO Yuko, SERA Toru, ITO Yu, HASEBE Takahiro, SAKUMA Noriyoshi, SATO Yuzuru, SUMI Hiroki
     
    I have made with the help of collaborators new developments of excursion theory from the three viewpoints as follows. (1) We proposed a theory of generalized refracted processes coming from two spectrally negative Levy processes and obtained remarkable results about generalization of classical exit problems as well as compound Poisson approximation of the refracted processes. (2) We established a general theory of functional limit theorem via convergence of excursions and deduced homogenization limit theorem of jumping-in processes. We proposed penalisation problems with various random clocks and succeeded in establishing a profound general theory of local time penalisations. (3) We generalized a known theory of arcsine laws of occupation times for infinite ergodic transforms of mapping dynamical systems with indifferent fixed points by enhancing it to a limit theorem of joint distributions based on the theory of multiray diffusions.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2014 -2018 
    Author : Sato Yuzuru, Shimaoka Daisuke, Fujimoto Koichi, Taga Gentaro
     
    Dynamics of membrane potential in mise whole brain is studied by using Amari neural field model with non-local coupling. As neuroscience, the phenomenology of the membrane potential propagation wave seen in spontaneous activity is studied. As mathematical science, the standard model of neural fields and the space-time continuous computation theory are studied. The results are the followings: (1)We identified the structure of the networks of neural fields based on the Allen Brain Atlas database. (2)The phenomenology of the membrane potential wave seen in spontaneous activity is constructed. (3) Robustness of the propagation wave and constructivity of the pulsar of the solitary wave are shown. (4) Since the non-local coupling is mathematically equivalent to the spatial curvature of the neural fields, it is found that the spatial geometry of neural fields influences the stability and division process of the solitary waves.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
    Date (from‐to) : 2014/04 -2017/03 
    Author : SAIKI YOSHITAKA, ESASHI Kunihiko, ONOZAKI Tamotsu, KOBAYASHI Miki U, SATO Yuzuru, YAMADA Michio, Chian Abraham C.-L., Das Suddhasattwa, Dock Chris B., Miranda Rodrigo A., Salgado-Flores Martin, Rempel Erico L., Sander Evelyn, Wu Jin, Yorke James A.
     
    Chaotic itinerancy is know as "Complex phenomena wandering among multi chaotic states irregularly", but does not have a certain mathematical characterization. We analyze a dynamics of a minimal model having the inevitable properties to be chaotic itinerancy. One of the models we studied was a two-dimensional torus map showing intermittency. It is expanding in x-direction and expanding or contracting in y-direction depending on the x value. We find that behind the dynamics exist the coexistence of repellers and saddles and quasi-periodic orbits. Through this study we develop a technique for calculating the Birkhoff average along a quasiperiodic orbit.
  • 低次元の確率分岐の研究
    文部科学省：特別研究員奨励費
    Date (from‐to) : 2015 -2017 
    Author : 佐藤譲
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2012 -2014 
    Author : SATO Yuzuru, SUMI Hiroki, YANO Koji
     
    Recently multiple noise-induced transitions, statistical periodicity, noise-induced reproducibility has been discovered in a broad class of nonlinear dynamical systems. The goal of this research is to establish a theory of noise-induced phenomena and to analyze complex phenomena including stochastic chaos in random dynamical systems quantitatively. The following (1)-(3) are the main results of this research. (1) Universality of multiple noise-induced transitions, statistical periodicity,noise-induced reproducibility has been confirmed numerically. (2) Experimental time series analysis for human brain wave and dice roll, and their modeling with random dynamical systems have been studied. (3) Stochastic resonance and noise-induced chaos are formalized in terms of bifurcation theory. Statistical periodicity is analyzed in terms of ergodic theory.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2012 -2014 
    Author : SUMI Hiroki, SATO Yuzuru
     
    I investigated the random dynamics of rational maps and the dynamics of semigroups of rational maps on the Riemann sphere. I showed that regarding random complex dynamics of polynomials, generically, the chaos of the averaged system disappears at any point in the Riemann sphere, due to the automatic cooperation of the generators. I investigated the iteration and spectral properties of transition operators acting on the space of (Hoelder) continuous functions on the Riemann sphere. I showed that the set of stable systems is open and dense in the space of random dynamical systems of polynomials. Also, I investigated the limit state functions. By taking a partial derivative of the function of probability of tending to a minimal set with respect to a probability parameter, I introduced a complex analogue of the Takagi function. I am developing multifractal analysis for limit state funtions and the complex analogue of the Takagi function.
  • Ministry of Education, Culture, Sports, Science and Technology：Grants-in-Aid for Scientific Research(基盤研究(C))
    Date (from‐to) : 2009 -2011 
    Author : Yuzuru SATO
     
    We extend the standard game dynamics to N-person game dynamics, Markov game dynamics, and continuous game dynamics and study them in terms of dynamical systems theory. (1) N-person game dynamics : The model is described as coupled map lattice and globally coupled maps, and shows complex nonlinear behavior such as traveling waves, spatiotemporal chaos, spatiotemporal intermittency. (2) Markov game dynamics : Players are modeled not by probability distributions, but by simple Markov systems. We analyze them dynamical systems theoretically and information theoretically. (3) Continuous game dynamics : Mixed strategies for continuous actions are modeled as probability density functions and a PDE model is constructed.
  • 文部科学省：科学研究費補助金(特別研究員奨励費)
    Date (from‐to) : 1999 -2000 
    Author : 佐藤 譲

Social Contribution

  • Open campus Hokkaido University
    Date (from-to) : 2006-Today
    Role : Lecturer
    Sponser, Organizer, Publisher  : Hokkaido University
    Event, Program, Title : Open campus Hokkaido University
  • 滞在型研究所での研究活動とその成果
    Date (from-to) : 2018/07/11
    Role : Panelist
    Sponser, Organizer, Publisher  : 東北大学
    Event, Program, Title : 紐帯の織り手：ネットワーク形成の極意とアカデミアの役割
  • Neural field dynamics in growing brains
    Date (from-to) : 2016-2016
    Role : Panelist
    Sponser, Organizer, Publisher  : AAAS
    Event, Program, Title : AAAS
  • Chaos and randomness
    Date (from-to) : 2016-2016
    Role : Lecturer
    Event, Program, Title : JSPSサイエンス・ダイアログ
  • Newtonian mechanics
    Date (from-to) : 2014-2014
    Role : Lecturer
    Sponser, Organizer, Publisher  : London Mathematical Laboratory
    Event, Program, Title : Summer project for secondary school students at London Japanese School

Media Coverage

  • New mechanism of stagnation in machine learning
    Date : 2021/12
    Writer: Myself
    Publisher, broadcasting station: 北海道大学
    https://www.hokudai.ac.jp/news/pdf/211221_pr2.pdf Internet
  • Uncertainty in prediction of SARS-Cov-2 infected population
    Date : 2020/10
    Writer: Myself
    Publisher, broadcasting station: 北海道大学
    https://www.hokudai.ac.jp/news/pdf/201030_pr2.pdf Internet
  • Mechanism of anomalous diffusion in random dynamical systems
    Date : 2019/05
    Writer: Myself
    Publisher, broadcasting station: 北海道大学
    https://www.hokudai.ac.jp/news/190514pr.pdf Internet
  • Stochastic chaos in turbulence
    Date : 2017/07
    Writer: Myself
    Publisher, broadcasting station: 北海道大学
    https://www.hokudai.ac.jp/news/170710pr.pdf Internet

Others

  • 2014 -2014 コンサルタント
    ZonLab, London, UK コンサルタント(2014-現在)
  • 2010 -2010 コンサルタント
    ヤマハ発動機株式会社 技術コンサルタント (2010-2013)

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