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Emergence of Self-Reproducing Metabolisms as recursive algorithms in an Artificial Chemistry

ARTIFICIAL LIFE 2022年第3-4期27卷 277-299页

作者： Kruszewski, German Mikolov, Tomas Naver Labs Europe Meylan France Czech Inst Informat Robot & Cybernet Prague Czech Republic Czech Tech Univ Prague Czech Republic

One of the main goals of Artificial Life is to research the conditions for the emergence of life, not necessarily as it is, but as it could be. Artificial chemistries are one of the most important tools for this purpose because they provide us with a basic framework to investigate under which conditions metabolisms capable of reproducing themselves, and ultimately, of evolving, can emerge. While there have been successful attempts at producing examples of emergent self-reproducing metabolisms, the set of rules involved remain too complex to shed much light on the underlying principles at work. In this article, we hypothesize that the key property needed for self-reproducing metabolisms to emerge is the existence of an autocatalyzed subset of Turing-complete reactions. We validate this hypothesis with a minimalistic artificial chemistry with conservation laws, which is based on a Turing-complete rewriting system called combinatory logic. Our experiments show that a single run of this chemistry, starting from a tabula rasa state, discovers-with no external intervention-a wide range of emergent structures including ones that self-reproduce in each cycle. All of these structures take the form of recursive algorithms that acquire basic constituents from the environment and decompose them in a process that is remarkably similar to biological metabolisms.

关键词： Artificial chemistry emergence self-reproduction metabolisms recursive algorithms

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Laguerre based predictors in discrete-time recursive algorithms: A solution for open-loop identification under oversampling

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IFAC-PapersOnLine 2017年第1期50卷 12911-12918页

作者： Vau, Bernard Bourlès, Henri SATIE Ecole normale supérieure de Cachan Cachan94230 France

In this paper we propose a novel formulation of the predictor used in open-loop recursive identification algorithms. The predicted output is expressed by means of an orthogonal Laguerre transfer functions basis. This predictor representation presents many advantages: It makes it possible to identify robustly oversampled systems without any bias in low frequency, and to obtain relevant reduced order models. The Laguerre pole plays the role of a tuning parameter enabling the selection of the best approximation frequency area. The proposed schemes address both output error and ARMAX systems. Simulation and experimental results show all the practical benefits provided by these algorithms. © 2017

关键词： Transfer functions Orthogonal functions Adaptive Control ARMAX model Identification algorithms Laguerre Output error models recursive algorithms recursive estimation

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Using recursive algorithms for the efficient identification of smoothing spline ANOVA models

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ASTA-ADVANCES IN STATISTICAL ANALYSIS 2010年第4期94卷 367-388页

作者： Ratto, Marco Pagano, Andrea Commiss European Communities Joint Res Ctr I-21027 Ispra VA Italy

In this paper we present a unified discussion of different approaches to the identification of smoothing spline analysis of variance (ANOVA) models: (i) the "classical" approach (in the line of Wahba in Spline Models for Observational Data, 1990;Gu in Smoothing Spline ANOVA Models, 2002;Storlie et al. in Stat. Sin., 2011) and (ii) the State-Dependent Regression (SDR) approach of Young in Nonlinear Dynamics and Statistics (2001). The latter is a nonparametric approach which is very similar to smoothing splines and kernel regression methods, but based on recursive filtering and smoothing estimation (the Kalman filter combined with fixed interval smoothing). We will show that SDR can be effectively combined with the "classical" approach to obtain a more accurate and efficient estimation of smoothing spline ANOVA models to be applied for emulation purposes. We will also show that such an approach can compare favorably with kriging.

关键词： Smoothing spline ANOVA models recursive algorithms Backfitting Sensitivity analysis

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recursive algorithms for identification of dual Youla-Kucera parametrized plant models in closed loop

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EUROPEAN JOURNAL OF CONTROL 2023年 69卷

作者： Landau, Ioan Dore Vau, Bernard Buche, Gabriel Univ Grenoble Alpes Gipsa Lab CNRS Grenoble INP F-38000 Grenoble France IXBLUE 12 Ave Coquelicots F-94385 Bonneuil Sur Marne France

The growing interest in using dual Youla Kucera plant parametrization for modeling plant uncertainties raises the need for recursive identification algorithms dedicated to the identification of these structures in closed loop in view of developing appropriate iterative tuning and adaptive control strategies. The paper presents recursive algorithms for identification in closed loop of dual Youla-Kucera parametrized plant models. These algorithms assure global asymptotic stability in the deterministic environment and allow to obtain unbiased parameter estimation in the presence of measurement noise when the plant model is in the model set. The paper also re-visit the Hansen scheme which allows to associate open loop type recursive identification algorithms for the identification of these structures in closed loop. When the plant model is not in the model set, comparison of the various algorithms is done in terms of the bias distribution. Further comparisons and performance evaluation is provided by simulations on some relevant examples and experimental identification in closed loop of a test bench for active noise control.(c) 2022 European Control Association. Published by Elsevier Ltd. All rights reserved.

关键词： System identification Youla-Kucera parametrization recursive algorithms Identification in closed loop Active noise control

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Applying Online Multiplayer Educational Games based on Generic Shells to Enhance Learning of recursive algorithms: Students' Preliminary Results 2

Applying Online Multiplayer Educational Games based on Gener...

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2nd European Conference on Games-Based Learning

作者： Rossiou, Eleni Papadakis, Spyros Univ Macedonia Thessaloniki Greece Hellen Open Univ Patras Greece

ISBN: (纸本)9781906638184

This paper provides a methodology for the implementation of an online multiplayer educational game during a virtual classroom. We investigate the students' preliminary results of applying a multiplayer Educational Game to enhance learning of recursive algorithms. The game was provided during synchronous tele-educational service complementary to f2f lecturing in the compulsory (first semester) course "algorithms with C" of the Department of Applied Informatics at the University of Macedonia, Greece. The Recursion game was embedded in one of a series of synchronous virtual classrooms, the Tutoring Tele-Meetings (TTMs) for complementing face-to-face classroom instruction in conventional higher education with methods and tools of Open and Distance Education. Virtual Classrooms were implemented on CENTRA Symposium platform, through the server of the Hellenic Open University. Educational games were created on the Online Educational Games Central (EGC) of TELUQ University of Quebec, Canada. Savie's online EGC was designed as a virtual meeting-place for those interested in using games for educational purposes. Teachers can choose between either using pre-defined available games. Teachers need to add the content based on pre-determined objectives to generate a new educational game adapted to their audience. Our goal using a synchronous educational game was to provide our students with the opportunity to our students to work together, to review, to ascertain misunderstandings and to integrate what they have learned about recursive algorithms. Thirty three (33) undergraduates of first semester "played" the web-based educational game "recursive algorithms", which was created based on the "Snakes and Ladders" shell. The usability of integrating an educational game based on EGC platform in virtual classrooms, the students' motivation and their perceptions and attitudes were investigated. In details, the way how students faced up the "game" educational approach and their results i

关键词： Educational game multiplayer recursive algorithms virtual classroom

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recursive algorithms FOR DISTRIBUTED FORESTS OF OCTREES

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SIAM JOURNAL ON SCIENTIFIC COMPUTING 2015年第5期37卷 C497-C531页

作者： Isaac, Tobin Burstedde, Carsten Wilcox, Lucas C. Ghattas, Omar Univ Texas Austin Inst Computat Engn & Sci Austin TX 78712 USA Univ Bonn Inst Numer Simulat D-53115 Bonn Germany Naval Postgrad Sch Dept Appl Math Monterrey CA 93943 USA Univ Texas Austin Dept Mech Engn Jackson Sch Geosci Austin TX 78712 USA Univ Texas Austin Inst Computat Engn & Sci Austin TX 78712 USA

The forest-of-octrees approach to parallel adaptive mesh refinement and coarsening has recently been demonstrated in the context of a number of large-scale PDE-based applications. Efficient reference software has been made freely available to the public both in the form of the standalone p4est library and more indirectly by the general-purpose finite element library deal. II, which has been equipped with a p4est backend. Although linear octrees, which store only leaf octants, have an underlying tree structure by definition, it is not fully exploited in previously published mesh-related algorithms. This is because tree branches are not explicitly stored and because the topological relationships in meshes, such as the adjacency between cells, introduce dependencies that do not respect the octree hierarchy. In this work, we combine hierarchical and topological relationships between octants to design efficient recursive algorithms that operate on distributed forests of octrees. We present three important algorithms with recursive implementations. The first is a parallel search for leaves matching any of a set of multiple search criteria, such as leaves that contain points or intersect polytopes. The second is a ghost layer construction algorithm that handles arbitrarily refined octrees that are not covered by previous algorithms, which require a 2: 1 condition between neighboring leaves. The third is a universal mesh topology iterator. This iterator visits every cell in a partition, as well as every interface (face, edge, and corner) between these cells. The iterator calculates the local topological information for every interface that it visits, taking into account the nonconforming interfaces that increase the complexity of describing the local topology. To demonstrate the utility of the topology iterator, we use it to compute the numbering and encoding of higher-order C-0 nodal basis functions used for finite elements. We analyze the complexity of the new recursive a

关键词： forest of octrees parallel adaptive mesh refinement Morton code recursive algorithms large-scale scientific computing

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Laguerre based predictors in discrete-time recursive algorithms: A solution for open-loop identification under oversampling

Laguerre based predictors in discrete-time recursive algorit...

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20th World Congress of the International-Federation-of-Automatic-Control (IFAC)

作者： Vau, Bernard Bourles, Henri SATIE Ecole Normale Super Cachan F-94230 Cachan France

In this paper we propose a novel formulation of the predictor used in open-loop recursive identification algorithms The predicted output is expressed by means of an orthogonal Laguerre transfer functions basis. This predictor representation presents many advantages: It makes it possible to identify robustly oversampled systems without any bias in low frequency, and to obtain relevant reduced order models. The Laguerre pole plays the role of a tuning parameter enabling the selection of the best approximation frequency area. The proposed schemes address both output error and ARMAX systems. Simulation and experimental results show all the practical benefits provided by these algorithms (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

关键词： Identification algorithms recursive algorithms recursive estimation output error model identification ARMAX model identification Laguerre transfer functions adaptive control

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recursive algorithms for unbalanced banded Toeplitz systems

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NUMERICAL LINEAR ALGEBRA WITH APPLICATIONS 2009年第7期16卷 561-587页

作者： Favati, P. Lotti, G. Menchi, O. Univ Pisa Dept Comp Sci I-56127 Pisa Italy Univ Parma Dept Math I-43100 Parma Italy IIT CNR Pisa Pisa Italy

Direct recursive algorithms for the solution of band Toeplitz systems are considered here. They exploit the displacement rank properties, which allow a large reduction of computational efforts and storage requirements. Their use of the Sherman-Morrison-Woodbury formula turns out to be particularly suitable for the case of unbalanced bandwidths. The computational costs of the algorithms under consideration are compared both in a theoretical and practical setting. Some stability issues are discussed as well. Copyright (C) 2009 John Wiley & Sons, Ltd.

关键词： recursive algorithms banded Toeplitz systems displacement rank

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The influence of model and measurement uncertainties on damage detection of experimental structures through recursive algorithms

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RELIABILITY ENGINEERING & SYSTEM SAFETY 2023年 239卷

作者： Ebrahimi, Mehrdad Nobahar, Elnaz Mohammadi, Reza Karami Farsangi, Ehsan Noroozinejad Noori, Mohammad Li, Shaofan KN Toosi Univ Technol Dept Civil Engn Tehran Iran Western Sydney Univ Urban Transformat Res Ctr UTRC Penrith NSW Australia Calif Polytech State Univ San Luis Obispo Dept Mech Engn San Luis Obispo CA USA Univ Leeds Sch Civil Engn Leeds LS2 9JT England Univ Calif Berkeley Dept Civil & Environm Engn Berkeley CA USA

In this work, we developed a framework for identifying frame-type structures regarding the measurement uncertainty and the uncertainty involved in inherent and structural parameters. The identification process is illustrated and examined on a one-eight-scale four-story moment-resisting steel frame under seismic excitation using two well-known recursive schemes: the Extended Kalman filter (EKF) and Unscented Kalman Filter (UKF) methods. The nonlinear system equations were assessed by applying a first-order instantaneous linearization approach through the EKF method. In contrast, the UKF algorithm employs several sample points to estimate moments of random variables' nonlinear transformations. A nonlinear transformation is applied to distribute sample points to derive the precise mean and covariance up to the second order of any nonlinearity. Accordingly, it is theoretically expected that the UKF algorithm is more capable of identifying the nonlinear systems and determining the unknown parameters than the EKF algorithm. The capability of the EKF and UKF algorithms was assessed by considering a 4-story moment-resisting steel frame with several inherent uncertainties, including the material behavior model, boundary conditions, and constraints. In addition to these uncertainties, the combination of acceleration and displacement responses of different structural levels is employed to evaluate the capability of the algorithms. The information entropy measure is used to investigate further the uncertainty of a group of established model parameters. As highlighted, a good agreement is observed between the results using the information entropy measure criterion and those using the UKF and EKF algorithms. The results illustrate that using the responses of fewer levels placed in the proper positions may lead to improved outcomes than those of more improperly positioned levels.

关键词： Uncertainty Extended Kalman filter Unscented Kalman filter recursive algorithms Damage detection Information entropy Sensors

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A general limit theorem for recursive algorithms and combinatorial structures

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ANNALS OF APPLIED PROBABILITY 2004年第1期14卷 378-418页

作者： Neininger, R Rüschendorf, L McGill Univ Sch Comp Sci Montreal PQ H3A 2K6 Canada Univ Freiburg Inst Math Stochast D-79104 Freiburg Germany

Limit laws are proven by the contraction method for random vectors of a recursive nature as they arise as parameters of combinatorial structures such as random trees or recursive algorithms, where we use the Zolotarev metric. In comparison to previous applications of this method, a general transfer theorem is derived which allows us to establish a limit law on the basis of the recursive structure and the asymptotics of the first and second moments of the sequence. In particular, a general asymptotic normality result is obtained by this theorem which typically cannot be handled by the more common l(2) metrics. As applications we derive quite automatically many asymptotic limit results ranging from the size of tries or m-ary search trees and path lengths in digital structures to mergesort and parameters of random recursive trees, which were previously shown by different methods one by one. We also obtain a related local density approximation result as well as a global approximation result. For the proofs of these results we establish that a smoothed density distance as well as a smoothed total variation distance can be estimated from above by the Zolotarev metric, which is the main tool in this article.

关键词： contraction method multivariate limit law asymptotic normality random trees recursive algorithms divide-and-conquer algorithm random recursive structures Zolotarev metric

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