3,857 research outputs found
Exponential wealth distribution in a random market. A rigorous explanation
In simulations of some economic gas-like models, the asymptotic regime shows
an exponential wealth distribution, independently of the initial wealth
distribution given to the system. The appearance of this statistical
equilibrium for this type of gas-like models is explained in a rigorous
analytical way.Comment: 9 pages, 4 figure
Exponential wealth distribution: a new approach from functional iteration theory
Exponential distribution is ubiquitous in the framework of multi-agent
systems. Usually, it appears as an equilibrium state in the asymptotic time
evolution of statistical systems. It has been explained from very different
perspectives. In statistical physics, it is obtained from the principle of
maximum entropy. In the same context, it can also be derived without any
consideration about information theory, only from geometrical arguments under
the hypothesis of equiprobability in phase space. Also, several multi-agent
economic models based on mappings, with random, deterministic or chaotic
interactions, can give rise to the asymptotic appearance of the exponential
wealth distribution. An alternative approach to this problem in the framework
of iterations in the space of distributions has been recently presented.
Concretely, the new iteration given by . It is found that the
exponential distribution is a stable fixed point of the former functional
iteration equation. From this point of view, it is easily understood why the
exponential wealth distribution (or by extension, other kind of distributions)
is asymptotically obtained in different multi-agent economic models.Comment: 6 pages, 5 figure
Non-linear response of single-molecule magnets: field-tuned quantum-to-classical crossovers
Quantum nanomagnets can show a field dependence of the relaxation time very
different from their classical counterparts, due to resonant tunneling via
excited states (near the anisotropy barrier top). The relaxation time then
shows minima at the resonant fields H_{n}=n D at which the levels at both sides
of the barrier become degenerate (D is the anisotropy constant). We showed that
in Mn12, near zero field, this yields a contribution to the nonlinear
susceptibility that makes it qualitatively different from the classical curves
[Phys. Rev. B 72, 224433 (2005)]. Here we extend the experimental study to
finite dc fields showing how the bias can trigger the system to display those
quantum nonlinear responses, near the resonant fields, while recovering an
classical-like behaviour for fields between them. The analysis of the
experiments is done with heuristic expressions derived from simple balance
equations and calculations with a Pauli-type quantum master equation.Comment: 4 pages, 3 figures. Submitted to Phys. Rev. B, brief report
Smoothening Functions and the Homomorphism Learning Problem
This thesis is an exploration of certain algebraic and geometrical aspects of the Learning With Errors (LWE) problem introduced in Reg05.
On the algebraic front, we view it as a Learning Homomorphisms with Noise problem, and provide a generic construction of a public-key cryptosystem based on this generalization.
On the geometric front, we explore the importance of the Gaussian distribution for the existing relationships between LWE and lattice problems.
We prove that their smoothing properties does not make them special, but rather, the fact that it is infinitely divisible and l2 symmetric are important properties that make the Gaussian unique
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