A simple dynamical model is presented for describing the gradual evolution of a variable number of species. The system is studied through Monte Carlo simulations using a lattice gas formalism. Each species is characterized by a single, scalar parameter (“adaptation”) which is changed, within...

In this paper, we analyse the response of music and book sales to an external field and a buyer herding. We distinguish endogenous and exogenous shocks. We focus on some case studies, whose data have been collected from ranking on amazon.com. We show that an ensemble of equivalent systems...

The Zipf analysis of n-words in random sequences and financial data series like the stock prices of a company has been performed. The bias as well as the resulting staircase structure of the Zipf plots are taken into account in the subsequent analysis. It is found that correlations for the sign...

The dynamic behavior of a multiagent system in which the agent size si is variable it is studied along a Lotka–Volterra approach. The agent size has hereby the meaning of the fraction of a given market that an agent is able to capture (market share). A Lotka–Volterra system of equations for...

The dynamics of a tree-like evolution is investigated as a function of the range k of the interactions between competing entities which are located at the extremities of the branches. Speciation (branching) events are supposed to be driven by extremal dynamics. Extinction events are allowed and...

The effective Hamiltonian approximation is used to calculate the critical temperature of a new class of magnetic systems, in which exchange integrals can be either of Ising or Heisenberg type. The values of the exchange integrals are supposed to be given according to different gaussian...

A religion affiliation can be considered as a “degree of freedom” of an agent on the human genre network. A brief review is given on the state of the art in data analysis and modelization of religious “questions” in order to suggest and if possible initiate further research, after using...

Applying any strategy requires some knowledge about the past state of the system. Unfortunately in the case of economy, collecting information is a difficult, expensive and time consuming process. Therefore, the information about the system is usually known only at the end of some well-defined...

The dynamic epidemic model considers the spreading of a cluster in a medium containing a fraction x of mobile particles which are pushed by the propagation front. This model is analytically studied on the Bethe lattice for any branching rate z. We give the exact solution xc = (z2 − 1)/z2 for...

For studying short-range time correlations in financial signals, we have envisaged to combine the Zipf method and the i-variability diagrams (VD) as useful tools. The 2-VD describes the local curvature short-range correlations. We have resulted into ranking the 2-VD data according to their...