133 research outputs found
Amplification by stochastic interference
A new method is introduced to obtain a strong signal by the interference of
weak signals in noisy channels. The method is based on the interference of 1/f
noise from parallel channels. One realization of stochastic interference is the
auditory nervous system. Stochastic interference may have broad potential
applications in the information transmission by parallel noisy channels
On the Numerical Study of the Complexity and Fractal Dimension of CMB Anisotropies
We consider the problem of numerical computation of the Kolmogorov complexity
and the fractal dimension of the anisotropy spots of Cosmic Microwave
Background (CMB) radiation. Namely, we describe an algorithm of estimation of
the complexity of spots given by certain pixel configuration on a grid and
represent the results of computations for a series of structures of different
complexity. Thus, we demonstrate the calculability of such an abstract
descriptor as the Kolmogorov complexity for CMB digitized maps. The correlation
of complexity of the anisotropy spots with their fractal dimension is revealed
as well. This technique can be especially important while analyzing the data of
the forthcoming space experiments.Comment: LATEX, 3 figure
Algebraic totality, towards completeness
Finiteness spaces constitute a categorical model of Linear Logic (LL) whose
objects can be seen as linearly topologised spaces, (a class of topological
vector spaces introduced by Lefschetz in 1942) and morphisms as continuous
linear maps. First, we recall definitions of finiteness spaces and describe
their basic properties deduced from the general theory of linearly topologised
spaces. Then we give an interpretation of LL based on linear algebra. Second,
thanks to separation properties, we can introduce an algebraic notion of
totality candidate in the framework of linearly topologised spaces: a totality
candidate is a closed affine subspace which does not contain 0. We show that
finiteness spaces with totality candidates constitute a model of classical LL.
Finally, we give a barycentric simply typed lambda-calculus, with booleans
and a conditional operator, which can be interpreted in this
model. We prove completeness at type for
every n by an algebraic method
Large deviations for a damped telegraph process
In this paper we consider a slight generalization of the damped telegraph
process in Di Crescenzo and Martinucci (2010). We prove a large deviation
principle for this process and an asymptotic result for its level crossing
probabilities (as the level goes to infinity). Finally we compare our results
with the analogous well-known results for the standard telegraph process
Universal fluctuations in subdiffusive transport
Subdiffusive transport in tilted washboard potentials is studied within the
fractional Fokker-Planck equation approach, using the associated continuous
time random walk (CTRW) framework. The scaled subvelocity is shown to obey a
universal law, assuming the form of a stationary Levy-stable distribution. The
latter is defined by the index of subdiffusion alpha and the mean subvelocity
only, but interestingly depends neither on the bias strength nor on the
specific form of the potential. These scaled, universal subvelocity
fluctuations emerge due to the weak ergodicity breaking and are vanishing in
the limit of normal diffusion. The results of the analytical heuristic theory
are corroborated by Monte Carlo simulations of the underlying CTRW
Generating natural language specifications from UML class diagrams
Early phases of software development are known to be problematic, difficult to manage and errors occurring during these phases are expensive to correct. Many systems have been developed to aid the transition from informal Natural Language requirements to semistructured or formal specifications. Furthermore, consistency checking is seen by many software engineers as the solution to reduce the number of errors occurring during the software development life cycle and allow early verification and validation of software systems. However, this is confined to the models developed during analysis and design and fails to include the early Natural Language requirements. This excludes proper user involvement and creates a gap between the original requirements and the updated and modified models and implementations of the system. To improve this process, we propose a system that generates Natural Language specifications from UML class diagrams. We first investigate the variation of the input language used in naming the components of a class diagram based on the study of a large number of examples from the literature and then develop rules for removing ambiguities in the subset of Natural Language used within UML. We use WordNet,a linguistic ontology, to disambiguate the lexical structures of the UML string names and generate semantically sound sentences. Our system is developed in Java and is tested on an independent though academic case study
On Martin-Löf convergence of Solomonoff’s mixture
We study the convergence of Solomonoff’s universal mixture on individual Martin-Löf random sequences. A new result is presented extending the work of Hutter and Muchnik (2004) by showing that there does not exist a universal mixture that converges on all Martin-Löf random sequences
The Vlasov continuum limit for the classical microcanonical ensemble
For classical Hamiltonian N-body systems with mildly regular pair interaction
potential it is shown that when N tends to infinity in a fixed bounded domain,
with energy E scaling quadratically in N proportional to e, then Boltzmann's
ergodic ensemble entropy S(N,E) has the asymptotic expansion S(N,E) = - N log N
+ s(e) N + o(N); here, the N log N term is combinatorial in origin and
independent of the rescaled Hamiltonian while s(e) is the system-specific
Boltzmann entropy per particle, i.e. -s(e) is the minimum of Boltzmann's
H-function for a perfect gas of "energy" e subjected to a combination of
externally and self-generated fields. It is also shown that any limit point of
the n-point marginal ensemble measures is a linear convex superposition of
n-fold products of the H-function-minimizing one-point functions. The proofs
are direct, in the sense that (a) the map E to S(E) is studied rather than its
inverse S to E(S); (b) no regularization of the microcanonical measure
Dirac(E-H) is invoked, and (c) no detour via the canonical ensemble. The proofs
hold irrespective of whether microcanonical and canonical ensembles are
equivalent or not.Comment: Final version; a few typos corrected; minor changes in the
presentatio
On Ruelle's construction of the thermodynamic limit for the classical microcanonical entropy
In this note we make a very elementary technical observation to the effect
that Ruelle's construction of the thermodynamic limit of the classical entropy
density defined with a regularized microcanonical measure actually establishes
the thermodynamic limit for the entropy density defined with the proper
microcanonical measure. At this stage a key formula is still derived from the
regularized measures. We also show that with only minor changes in the proof
the regularization of the microcanonical measure is actually not needed at all.Comment: Short communication (7p), accepted for publication in J.Stat.Phy
Antirealism and the Roles of Truth
Geschiedenis van Antieke en Middeleeuwse Semantie
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