Mixing and relaxation dynamics of the Henon map at the edge of chaos

The mixing properties (or sensitivity to initial conditions) and relaxation dynamics of the Henon map, together with the connection between these concepts, have been explored numerically at the edge of chaos. It is found that the results are consistent with those coming from one-dimensional dissipative maps. This constitutes the first verification of the scenario in two-dimensional cases and obviously reinforces the idea of weak mixing and weak chaos. Keywords: Nonextensive thermostatistics, Henon map, dynamical systemsComment: 10 pages with 3 fig

Damage spreading in 2-dimensional isotropic and anisotropic Bak-Sneppen models

We implement the damage spreading technique on 2-dimensional isotropic and anisotropic Bak-Sneppen models. Our extensive numerical simulations show that there exists a power-law sensitivity to the initial conditions at the statistically stationary state (self-organized critical state). Corresponding growth exponent $\alpha$ for the Hamming distance and the dynamical exponent $z$ are calculated. These values allow us to observe a clear data collapse of the finite size scaling for both versions of the Bak-Sneppen model. Moreover, it is shown that the growth exponent of the distance in the isotropic and anisotropic Bak-Sneppen models is strongly affected by the choice of the transient time.Comment: revised version, 9 pages, 5 eps figures, use of svjour.st

Dissipative maps at the chaos threshold: Numerical results for the single-site map

We numerically study, at the edge of chaos, the behaviour of the sibgle-site map $x_{t+1}=x_t-x_t/(x_t^2+\gamma^2)$, where $\gamma$ is the map parameter.Comment: 8 pages with 4 figures, submitted to Physica

Asymmetric Unimodal Maps: Some Results from q-generalized Bit Cumulants

In this study, using q-generalized bit cumulants (q is the nonextensivity parameter of the recently introduced Tsallis statistics), we investigate the asymmetric unimodal maps. The study of the q-generalized second cumulant of these maps allows us to determine, for the first time, the dependence of the inflexion paremeter pairs (z_1,z_2) to the nonextensivity parameter q. This behaviour is found to be very similar to that of the logistic-like maps (z_1=z_2=z) reported recently by Costa et al. [Phys.Rev.E 56 (1997) 245].Comment: 6 pages with 3 fig

Sensitivity function and entropy increase rates for z-logistic map family at the edge of chaos

It is well known that, for chaotic systems, the production of relevant entropy (Boltzmann-Gibbs) is always linear and the system has strong (exponential) sensitivity to initial conditions. In recent years, various numerical results indicate that basically the same type of behavior emerges at the edge of chaos if a specific generalization of the entropy and the exponential are used. In this work, we contribute to this scenario by numerically analysing some generalized nonextensive entropies and their related exponential definitions using $z$-logistic map family. We also corroborate our findings by testing them at accumulation points of different cycles.Comment: 9 pages, 2 fig

Two-dimensional maps at the edge of chaos: Numerical results for the Henon map

The mixing properties (or sensitivity to initial conditions) of two-dimensional Henon map have been explored numerically at the edge of chaos. Three independent methods, which have been developed and used so far for the one-dimensional maps, have been used to accomplish this task. These methods are (i)measure of the divergence of initially nearby orbits, (ii)analysis of the multifractal spectrum and (iii)computation of nonextensive entropy increase rates. The obtained results strongly agree with those of the one-dimensional cases and constitute the first verification of this scenario in two-dimensional maps. This obviously makes the idea of weak chaos even more robust.Comment: 4 pages, 3 figure

Generalized Huberman-Rudnick scaling law and robustness of qq-Gaussian probability distributions

We generalize Huberman-Rudnick universal scaling law for all periodic windows of the logistic map and show the robustness of $q$-Gaussian probability distributions in the vicinity of chaos threshold. Our scaling relation is universal for the self-similar windows of the map which exhibit period-doubling subharmonic bifurcations. Using this generalized scaling argument, for all periodic windows, as chaos threshold is approached, a developing convergence to $q$-Gaussian is numerically obtained both in the central regions and tails of the probability distributions of sums of iterates.Comment: 13 pages, 3 figure

Damage spreading in the Bak-Sneppen model: Sensitivity to the initial conditions and equilibration dynamics

The short-time and long-time dynamics of the Bak-Sneppen model of biological evolution are investigated using the damage spreading technique. By defining a proper Hamming distance measure, we are able to make it exhibits an initial power-law growth which, for finite size systems, is followed by a decay towards equilibrium. In this sense, the dynamics of self-organized critical states is shown to be similar to the one observed at the usual critical point of continuous phase-transitions and at the onset of chaos of non-linear low-dimensional dynamical maps. The transient, pre-asymptotic and asymptotic exponential relaxation of the Hamming distance between two initially uncorrelated equilibrium configurations is also shown to be fitted within a single mathematical framework. A connection with nonextensive statistical mechanics is exhibited.Comment: 6 pages, 4 figs, revised version, accepted for publication in Int.J.Mod.Phys.C 14 (2003

Convergence dynamics of 2-dimensional isotropic and anisotropic Bak-Sneppen models

The conventional Hamming distance measurement captures only the short-time dynamics of the displacement between the uncorrelated random configurations. The minimum difference technique introduced by Tirnakli and Lyra [Int. J. Mod. Phys. C 14, 805 (2003)] is used to study the short-time and long-time dynamics of the two distinct random configurations of the isotropic and anisotropic Bak-Sneppen models on a square lattice. Similar to 1-dimensional case, the time evolution of the displacement is intermittent. The scaling behavior of the jump activity rate and waiting time distribution reveal the absence of typical spatial-temporal scales in the mechanism of displacement jumps used to quantify the convergence dynamics.Comment: 7 pages, 4 eps figures, 1 bbl fil