2,369 research outputs found
Lattice structures for bisimilar Probabilistic Automata
The paper shows that there is a deep structure on certain sets of bisimilar
Probabilistic Automata (PA). The key prerequisite for these structures is a
notion of compactness of PA. It is shown that compact bisimilar PA form
lattices. These results are then used in order to establish normal forms not
only for finite automata, but also for infinite automata, as long as they are
compact.Comment: In Proceedings INFINITY 2013, arXiv:1402.661
Wake up and smell the coffee, or find the technoserf dead
This document is part of a digital collection provided by the Martin P. Catherwood Library, ILR School, Cornell University, pertaining to the effects of globalization on the workplace worldwide. Special emphasis is placed on labor rights, working conditions, labor market changes, and union organizing.CLW_2011_Report_China_wake_up.pdf: 59 downloads, before Oct. 1, 2020
Magnons in the ferromagnetic Kondo-lattice model
The magnetic properties of the ferromagnetic Kondo-lattice model (FKLM) are
investigated. Starting from an analysis of the magnon spectrum in the spin-wave
regime, we examine the ferromagnetic stability as a function of the occupation
of the conduction band and the strength of the coupling between the
localised moments and the conduction electrons. From the properties of the
spin-wave stiffness the ferromagnetic phase at zero temperature is derived.
Using an approximate formula the critical temperature is calculated as a
function of and .Comment: 15 pages, 6 figures, to appear in phys. stat. sol.
Markovian embedding of fractional superdiffusion
The Fractional Langevin Equation (FLE) describes a non-Markovian Generalized
Brownian Motion with long time persistence (superdiffusion), or
anti-persistence (subdiffusion) of both velocity-velocity correlations, and
position increments. It presents a case of the Generalized Langevin Equation
(GLE) with a singular power law memory kernel. We propose and numerically
realize a numerically efficient and reliable Markovian embedding of this
superdiffusive GLE, which accurately approximates the FLE over many, about r=N
lg b-2, time decades, where N denotes the number of exponentials used to
approximate the power law kernel, and b>1 is a scaling parameter for the
hierarchy of relaxation constants leading to this power law. Besides its
relation to the FLE, our approach presents an independent and very flexible
route to model anomalous diffusion. Studying such a superdiffusion in tilted
washboard potentials, we demonstrate the phenomenon of transient hyperdiffusion
which emerges due to transient kinetic heating effects.Comment: EPL, in pres
TIPPtool: Compositional Specification and Analysis of Markovian Performance Models
In this short paper we briefly describe a tool which is based on a Markovian stochastic process algebra. The tool offers both model specification and quantitative model analysis in a compositional fashion, wrapped in a userfriendly graphical front-end
Markovian embedding of non-Markovian superdiffusion
We consider different Markovian embedding schemes of non-Markovian stochastic
processes that are described by generalized Langevin equations (GLE) and obey
thermal detailed balance under equilibrium conditions. At thermal equilibrium
superdiffusive behavior can emerge if the total integral of the memory kernel
vanishes. Such a situation of vanishing static friction is caused by a
super-Ohmic thermal bath. One of the simplest models of ballistic
superdiffusion is determined by a bi-exponential memory kernel that was
proposed by Bao [J.-D. Bao, J. Stat. Phys. 114, 503 (2004)]. We show that this
non-Markovian model has infinitely many different 4-dimensional Markovian
embeddings. Implementing numerically the simplest one, we demonstrate that (i)
the presence of a periodic potential with arbitrarily low barriers changes the
asymptotic large time behavior from free ballistic superdiffusion into normal
diffusion; (ii) an additional biasing force renders the asymptotic dynamics
superdiffusive again. The development of transients that display a
qualitatively different behavior compared to the true large-time asymptotics
presents a general feature of this non-Markovian dynamics. These transients
though may be extremely long. As a consequence, they can be even mistaken as
the true asymptotics. We find that such intermediate asymptotics exhibit a
giant enhancement of superdiffusion in tilted washboard potentials and it is
accompanied by a giant transient superballistic current growing proportional to
with an exponent that can exceed
the ballistic value of two
A tool for model-checking Markov chains
Markov chains are widely used in the context of the performance and reliability modeling of various systems. Model checking of such chains with respect to a given (branching) temporal logic formula has been proposed for both discrete [34, 10] and continuous time settings [7, 12]. In this paper, we describe a prototype model checker for discrete and continuous-time Markov chains, the Erlangen-Twente Markov Chain Checker EÎMC2, where properties are expressed in appropriate extensions of CTL. We illustrate the general benefits of this approach and discuss the structure of the tool. Furthermore, we report on successful applications of the tool to some examples, highlighting lessons learned during the development and application of EÎMC2
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