arXiv subjects

Milan Rajkovic

Publications and source records attributed to Milan Rajkovic.

12 recordsLinked to original sources

arXiv2015

Persistent topological features of dynamical systems

A general method for constructing simplicial complex from observed time series of dynamical systems based on the delay coordinate reconstruction procedure is presented. The obtained simplicial complex preserves all pertinent topological features of the reconstructed phase space and it may be analyzes from topological, combinatorial and algebraic aspects. In focus of this study is the computation of homology of the invariant set of some well known dynamical systems which display chaotic behavior. Persistent homology of simplicial complex and its relationship with the embedding dimensions are examined by studying the lifetime of topological features and topological noise. The consistency of topological properties for different dynamic regimes and embedding dimensions is examined. The obtained results shed new light on the topological properties of the reconstructed phase space and open up new possibilities for application of advanced topological methods. the method presented here may be used as a generic method for constructing simplicial complex from a scalar time series which has a number of advantages compared to the mapping of the time series to a complex network.

nlin.CD↗

arXiv2012

Consensus Formation on Simplicial Complex of Opinions

Geometric realization of opinion is considered as a simplex and the opinion space of a group of individuals is a simplicial complex whose topological features are monitored in the process of opinion formation. The agents are physically located on the nodes of the scale-free network. Social interactions include all concepts of social dynamics present in the mainstream models augmented by four additional interaction mechanisms which depend on the local properties of opinions and their overlapping properties. The results pertaining to the formation of consensus are of particular interest. An analogy with quantum mechanical pure states is established through the application of the high dimensional combinatorial Laplacian.

physics.soc-ph↗

arXiv2012

Quantifying Self-Organization with Optimal Wavelets

The optimal wavelet basis is used to develop quantitative, experimentally applicable criteria for self-organization. The choice of the optimal wavelet is based on the model of self-organization in the wavelet tree. The framework of the model is founded on the wavelet-domain hidden Markov model and the optimal wavelet basis criterion for self-organization which assumes inherent increase in statistical complexity, the information content necessary for maximally accurate prediction of the system's dynamics. At the same time the method, presented here for the one-dimensional data of any type, performs superior denoising and may be easily generalized to higher dimensions.

math-ph↗

arXiv2008

Persistent Homology of Complex Networks

Long lived topological features are distinguished from short lived ones (considered as topological noise) in simplicial complexes constructed from complex networks. A new topological invariant, persistent homology, is determined and presented as a parametrized version of a Betti number. Complex networks with distinct degree distributions exhibit distinct persistent topological features. Persistent toplogical attributes, shown to be related to robust quality of networks, also reflect defficiency in certain connectivity properites of networks. Random networks, networks with exponential conectivity distribution and scale-free networks were considered for homological persistency analysis.

math-ph↗

arXiv2005

Integration of Third Order Ordinary Differential Equations Possessing Two-Parameter Symmetry Group by Lie's Method

The solution of a class of third order ordinary differential equations possessing two parameter Lie symmetry group is obtained by group theoretic means. It is shown that reduction to quadratures is possible according to two scenarios: 1) if upon first reduction of order the obtained second order ordinary differential equation besides the inherited point symmetry acquires at least one more new point symmetry (possibly a hidden symmetry of Type II). 2) First, reduction paths of the fourth order differential equations with four parameter symmetry group leading to the first order equation possessing one known (inherited) symmetry are constructed. Then, reduction paths along which a third order equation possessing two-parameter symmetry group appears are singled out and followed until a first order equation possessing one known (inherited) symmetry are obtained. The method uses conditions for preservation, disappearance and reappearance of point symmetries.

math-ph↗

arXiv2005

Bifurcations in nonlinear models of fluid-conveying pipes supported at both ends

Stationary bifurcations in several nonlinear models of fluid conveying pipes fixed at both ends are analyzed with the use of Lyapunov-Schmidt reduction and singularity theory. Influence of gravitational force, curvature and vertical elastic support on various properties of bifurcating solutions are investigated. In particular the conditions for occurrence of supercritical and subcritical bifurcations are presented for the models of Holmes, Thurman and Mote, and Paidoussis.

nlin.CD↗

arXiv2005

Cooperative Parrondo's Games on a Two-dimensional Lattice

Cooperative Parrondo's games on a regular two dimensional lattice are analyzed based on the computer simulations and on the discrete-time Markov chain model with exact transition probabilities. The paradox appears in the vicinity of the probabilites characterisitic of the "voter model", suggesting practical applications. As in the one-dimensional case, winning and the occurrence of the paradox depends on the number of players.

cond-mat.stat-mech↗

arXiv2005

The Role of Three-dimensional Subalgebra in the Analysis of Hidden Symmetries of Differential Equations

Some new properties of symmetries that disappear as point symmetries after the first reduction of order of an ODE and reappear after the second are analyzed from the aspect of three-dimensional subalgebra of symmetries of differential equations. The form of a hidden symmetry is shown to consist of two parts, one of which always remains preserved as a point symmetry, and the second (fundamental) part which behaves as the complete hidden symmetry. Symmetry that disappears as point symmetry and remains hidden (non-local) during $n$ reductions of order before reappearing as a point symmetry is also introduced and termed convertible symmetry of order $n-1.$ We discuss the necessity for such classification in order to distinguish them from hidden symmetries of type I and type II, which are defined with respect to reduction of order by one.

math-ph↗

arXiv2004

Entropic nonextensivity as a measure of time series complexity

Information entropy is applied to the analysis of time series generated by dynamical systems. Complexity of a temporal or spatio-temporal signal is defined as the difference between the sum of entropies of the local linear regions of the trajectory manifold and the entropy of the globally linearized manifold. When the entropies are Tsallis entropies the complexity is characterized by the value of q.

nlin.CD↗

arXiv2003

One Dimensional Asynchronous Cooperative Parrondo's Games

An analytical result and an algorithm are derived for the probability distribution of the one-dimensional cooperative Parrondo's games. We show that winning and the occurrence of the paradox depends on the number of players. Analytical results are compared to the results of the computer simulation and to the results based on the mean-field approach.

cond-mat.stat-mech↗

arXiv2003

Synchronous Cooperative Parrondo's Games

Inspired by asynchronous cooperative Parrondo's games we introduce two new types of games in which all players simultaneously play game A or game B or a combination of these two games. These two types of games differ in the way a combination of games A and B is played. In the first type of synchronous games, all players simultaneously play the same game (either A or B), while in the second type players simultaneously play the game of their choice, i.e. A or B. We show that for these games, as in the case of asynchronous games, occurrence of the paradox depends on the number of players. An analytical result and an algorithm are derived for the probability distribution of these games.

cond-mat.stat-mech↗

arXiv2003

Qunatifying Complexity in the Minority Game

A Lempel-Ziv complexity measure is introduced into the theory of a Minority Game (MG) in order to capture some features that volatility, one of the central quantities in this model of interacting agents, is not able to. Extracted solely from the binary string of outcomes of the game complexity offers new and valuable information on collective behavior of players. Also, we show that an expression for volatility may be included in the analytical expression for complexity.

cond-mat.dis-nn↗