61 research outputs found
Inequalities of wealth distribution in a conservative economy
We analyze a conservative market model for the competition among economic
agents in a close society. A minimum dynamics ensures that the poorest agent
has a chance to improve its economic welfare. After a transient, the system
self-organizes into a critical state where the wealth distribution have a
minimum threshold, with almost no agent below this poverty line, also, very few
extremely rich agents are stable in time. Above the poverty line the
distribution follows an exponential behavior. The local solution exhibits a low
Gini index, while the mean field solution of the model generates a wealth
distribution similar to welfare states like Sweden.Comment: 7 pages, 4 figures, submitted to Physica A, Proceedings of the VIII
LAWNP, Salvador, Brazil, 200
Living in an Irrational Society: Wealth Distribution with Correlations between Risk and Expected Profits
Different models to study the wealth distribution in an artificial society
have considered a transactional dynamics as the driving force. Those models
include a risk aversion factor, but also a finite probability of favoring the
poorer agent in a transaction. Here we study the case where the partners in the
transaction have a previous knowledge of the winning probability and adjust
their risk aversion taking this information into consideration. The results
indicate that a relatively equalitarian society is obtained when the agents
risk in direct proportion to their winning probabilities. However, it is the
opposite case that delivers wealth distribution curves and Gini indices closer
to empirical data. This indicates that, at least for this very simple model,
either agents have no knowledge of their winning probabilities, either they
exhibit an ``irrational'' behavior risking more than reasonable.Comment: 7 pages, 8 figure
The renormalized jellium model for spherical and cylindrical colloids
Starting from a mean-field description for a dispersion of highly charged
spherical or (parallel) rod-like colloids, we introduce the simplification of a
homogeneous background to include the contribution of other polyions to the
static field created by a tagged polyion. The charge of this background is
self-consistently renormalized to coincide with the polyion effective charge,
the latter quantity thereby exhibiting a non-trivial density dependence, which
directly enters into the equation of state through a simple analytical
expression. The good agreement observed between the pressure calculated using
the renormalized jellium and Monte Carlo simulations confirms the relevance of
the {renormalized} jellium model for theoretical and experimental purposes and
provides an alternative to the Poisson-Boltzmann cell model since it is free of
some of the intrinsic limitations of this approach
Economic exchanges in a stratified society: End of the middle class?
We study the effect of the social stratification on the wealth distribution
on a system of interacting economic agents that are constrained to interact
only within their own economic class. The economical mobility of the agents is
related to its success in exchange transactions. Different wealth distributions
are obtained as a function of the width of the economic class. We find a range
of widths in which the society is divided in two classes separated by a deep
gap that prevents further exchange between poor and rich agents. As a
consequence, the middle wealth class is eliminated. The high values of the Gini
indices obtained in these cases indicate a highly unequal society. On the other
hand, lower and higher widths induce lower Gini indices and a fairer wealth
distribution.Comment: 7 pages, 2 figures, 1 table, to appear in Physica
Broad class of nonlinear Langevin equations with drift and diffusion cofficients separable in time and space: Generalized n-moment, ergodicity, Einstein relation and fluctuations of the system
A wide class of nonlinear Langevin equations with drift and diffusion
coefficients separable in time and space driven by the Gaussian white noise is
analyzed in terms of a generalized n-moment. We show the system may present
ergodic property, a key property in statistical mechanics, for
space-time-dependent drift and diffusion coefficients. A generalized Einstein
relation is also obtained. Besides, we show that the first two generalized
moments and variance are useful to describe the drift and fluctuations of the
system.Comment: 22 pages, 4 figure
Correlation between Risk Aversion and Wealth distribution
Different models of capital exchange among economic agents have been proposed
recently trying to explain the emergence of Pareto's wealth power law
distribution. One important factor to be considered is the existence of risk
aversion. In this paper we study a model where agents posses different levels
of risk aversion, going from uniform to a random distribution. In all cases the
risk aversion level for a given agent is constant during the simulation. While
for a uniform and constant risk aversion the system self-organizes in a
distribution that goes from an unfair ``one takes all'' distribution to a
Gaussian one, a random risk aversion can produce distributions going from
exponential to log-normal and power-law. Besides, interesting correlations
between wealth and risk aversion are found.Comment: 8 pages, 7 figures, submitted to Physica A, Proceedings of the VIII
LAWNP, Salvador, Brazil, 200
Wealth redistribution with finite resources
We present a simplified model for the exploitation of finite resources by
interacting agents, where each agent receives a random fraction of the
available resources. An extremal dynamics ensures that the poorest agent has a
chance to change its economic welfare. After a long transient, the system
self-organizes into a critical state that maximizes the average performance of
each participant. Our model exhibits a new kind of wealth condensation, where
very few extremely rich agents are stable in time and the rest stays in the
middle class.Comment: 4 pages, 3 figures, RevTeX 4 styl
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