1,246 research outputs found
Predictability: a way to characterize Complexity
Different aspects of the predictability problem in dynamical systems are
reviewed. The deep relation among Lyapunov exponents, Kolmogorov-Sinai entropy,
Shannon entropy and algorithmic complexity is discussed. In particular, we
emphasize how a characterization of the unpredictability of a system gives a
measure of its complexity. Adopting this point of view, we review some
developments in the characterization of the predictability of systems showing
different kind of complexity: from low-dimensional systems to high-dimensional
ones with spatio-temporal chaos and to fully developed turbulence. A special
attention is devoted to finite-time and finite-resolution effects on
predictability, which can be accounted with suitable generalization of the
standard indicators. The problems involved in systems with intrinsic randomness
is discussed, with emphasis on the important problems of distinguishing chaos
from noise and of modeling the system. The characterization of irregular
behavior in systems with discrete phase space is also considered.Comment: 142 Latex pgs. 41 included eps figures, submitted to Physics Reports.
Related information at this http://axtnt2.phys.uniroma1.i
A Basic Framework for the Cryptanalysis of Digital Chaos-Based Cryptography
Chaotic cryptography is based on the properties of chaos as source of
entropy. Many different schemes have been proposed to take advantage of those
properties and to design new strategies to encrypt information. However, the
right and efficient use of chaos in the context of cryptography requires a
thorough knowledge about the dynamics of the selected chaotic system. Indeed,
if the final encryption system reveals enough information about the underlying
chaotic system it could be possible for a cryptanalyst to get the key, part of
the key or some information somehow equivalent to the key just analyzing those
dynamical properties leaked by the cryptosystem. This paper shows what those
dynamical properties are and how a cryptanalyst can use them to prove the
inadequacy of an encryption system for the secure exchange of information. This
study is performed through the introduction of a series of mathematical tools
which should be the basic framework of cryptanalysis in the context of digital
chaos-based cryptography.Comment: 6 pages, 5 figure
Mean-Field Coupled Systems and Self-Consistent Transfer Operators: A Review
In this review we survey the literature on mean-field coupled maps. We start
with the early works from the physics literature, arriving to some recent
results from ergodic theory studying the thermodynamic limit of globally
coupled maps and the associated self-consistent transfer operators. We also
give few pointers to related research fields dealing with mean-field coupled
systems in continuous time, and applications
Probabilistic and thermodynamic aspects of dynamical systems
The probabilistic approach to dynamical systems giving rise to irreversible behavior at the macroscopic, mesoscopic, and microscopic levels of description is outlined. Signatures of the complexity of the underlying dynamics on the spectral properties of the Liouville, Frobenius-Perron, and Fokker-Planck operators are identified. Entropy and entropy production-like quantities are introduced and the connection between their properties in nonequilibrium steady states and the characteristics of the dynamics in phase space are explored.info:eu-repo/semantics/publishe
Online Abstractions for Interconnected Multi-Agent Control Systems
In this report, we aim at the development of an online abstraction framework
for multi-agent systems under coupled constraints. The motion capabilities of
each agent are abstracted through a finite state transition system in order to
capture reachability properties of the coupled multi-agent system over a finite
time horizon in a decentralized manner. In the first part of this work, we
define online abstractions by discretizing an overapproximation of the agents'
reachable sets over the horizon. Then, sufficient conditions relating the
discretization and the agent's dynamics properties are provided, in order to
quantify the transition possibilities of each agent.Comment: 22 pages. arXiv admin note: text overlap with arXiv:1603.0478
Information geometric methods for complexity
Research on the use of information geometry (IG) in modern physics has
witnessed significant advances recently. In this review article, we report on
the utilization of IG methods to define measures of complexity in both
classical and, whenever available, quantum physical settings. A paradigmatic
example of a dramatic change in complexity is given by phase transitions (PTs).
Hence we review both global and local aspects of PTs described in terms of the
scalar curvature of the parameter manifold and the components of the metric
tensor, respectively. We also report on the behavior of geodesic paths on the
parameter manifold used to gain insight into the dynamics of PTs. Going
further, we survey measures of complexity arising in the geometric framework.
In particular, we quantify complexity of networks in terms of the Riemannian
volume of the parameter space of a statistical manifold associated with a given
network. We are also concerned with complexity measures that account for the
interactions of a given number of parts of a system that cannot be described in
terms of a smaller number of parts of the system. Finally, we investigate
complexity measures of entropic motion on curved statistical manifolds that
arise from a probabilistic description of physical systems in the presence of
limited information. The Kullback-Leibler divergence, the distance to an
exponential family and volumes of curved parameter manifolds, are examples of
essential IG notions exploited in our discussion of complexity. We conclude by
discussing strengths, limits, and possible future applications of IG methods to
the physics of complexity.Comment: review article, 60 pages, no figure
Data based identification and prediction of nonlinear and complex dynamical systems
We thank Dr. R. Yang (formerly at ASU), Dr. R.-Q. Su (formerly at ASU), and Mr. Zhesi Shen for their contributions to a number of original papers on which this Review is partly based. This work was supported by ARO under Grant No. W911NF-14-1-0504. W.-X. Wang was also supported by NSFC under Grants No. 61573064 and No. 61074116, as well as by the Fundamental Research Funds for the Central Universities, Beijing Nova Programme.Peer reviewedPostprin
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