7,441 research outputs found
A framework for redescription set construction
Redescription mining is a field of knowledge discovery that aims at finding
different descriptions of similar subsets of instances in the data. These
descriptions are represented as rules inferred from one or more disjoint sets
of attributes, called views. As such, they support knowledge discovery process
and help domain experts in formulating new hypotheses or constructing new
knowledge bases and decision support systems. In contrast to previous
approaches that typically create one smaller set of redescriptions satisfying a
pre-defined set of constraints, we introduce a framework that creates large and
heterogeneous redescription set from which user/expert can extract compact sets
of differing properties, according to its own preferences. Construction of
large and heterogeneous redescription set relies on CLUS-RM algorithm and a
novel, conjunctive refinement procedure that facilitates generation of larger
and more accurate redescription sets. The work also introduces the variability
of redescription accuracy when missing values are present in the data, which
significantly extends applicability of the method. Crucial part of the
framework is the redescription set extraction based on heuristic
multi-objective optimization procedure that allows user to define importance
levels towards one or more redescription quality criteria. We provide both
theoretical and empirical comparison of the novel framework against current
state of the art redescription mining algorithms and show that it represents
more efficient and versatile approach for mining redescriptions from data
Multi-Component Model Sets and Invariant Densities
Model sets (also called cut and project sets) are generalizations of
lattices, and multi-component model sets are generalizations of lattices with
colourings. In this paper, we study self-similarities of multi-component model
sets. The main point may be simply summarized: whenever there is a
self-similarity, there are also naturally related density functions. As in the
case of ordinary model sets, we show that invariant densities exist and that
they produce absolutely continuous invariant measures in internal space, these
features now appearing in matrix form. We establish a close connection between
the theory of invariant densities and the spectral theory of matrix continuous
refinement operators.Comment: 12 pages, 2 figures, to appear in: Aperiodic 9
BitSim: An Algebraic Similarity Measure for Description Logics Concepts
In this paper, we propose an algebraic similarity measure {\sigma}BS (BS
stands for BitSim) for assigning semantic similarity score to concept
definitions in ALCH+ an expressive fragment of Description Logics (DL). We
define an algebraic interpretation function, I_B, that maps a concept
definition to a unique string ({\omega}_B) called bit-code) over an alphabet
{\Sigma}_B of 11 symbols belonging to L_B - the language over P B. IB has
semantic correspondence with conventional model-theoretic interpretation of DL.
We then define {\sigma}_BS on L_B. A detailed analysis of I_B and {\sigma}_BS
has been given
Cumulants and convolutions via Abel polynomials
We provide an unifying polynomial expression giving moments in terms of
cumulants, and viceversa, holding in the classical, boolean and free setting.
This is done by using a symbolic treatment of Abel polynomials. As a
by-product, we show that in the free cumulant theory the volume polynomial of
Pitman and Stanley plays the role of the complete Bell exponential polynomial
in the classical theory. Moreover via generalized Abel polynomials we construct
a new class of cumulants, including the classical, boolean and free ones, and
the convolutions linearized by them. Finally, via an umbral Fourier transform,
we state a explicit connection between boolean and free convolution
A tube formula for the Koch snowflake curve, with applications to complex dimensions
A formula for the interior epsilon-neighborhood of the classical von Koch
snowflake curve is computed in detail. This function of epsilon is shown to
match quite closely with earlier predictions of what it should be, but is also
much more precise. The resulting `tube formula' is expressed in terms of the
Fourier coefficients of a suitable nonlinear and periodic analogue of the
standard Cantor staircase function and reflects the self-similarity of the Koch
curve. As a consequence, the possible complex dimensions of the Koch snowflake
are computed explicitly.Comment: Updated version: new method of calculation drastically reduces length
of proof. 18 pages, 10 figure
Self-Similar Measures for Quasicrystals
We study self-similar measures of Hutchinson type, defined by compact
families of contractions, both in a single and multi-component setting. The
results are applied in the context of general model sets to infer, via a
generalized version of Weyl's Theorem on uniform distribution, the existence of
invariant measures for families of self-similarities of regular model sets.Comment: 42 pages, several figure
A Semantic-Based Approach for Detecting and Decomposing God Classes
Cohesion is a core design quality that has a great impact on posterior
development and maintenance. By the nature of software, the cohesion of a
system is diminished as the system evolves. God classes are code defects
resulting from software evolution, having heterogeneous responsibilities highly
coupled with other classes and often large in size, which makes it difficult to
maintain the system. The existing work on identifying and decomposing God
classes heavily relies on internal class information to identify God classes
and responsibilities. However, in object-oriented systems, responsibilities
should be analyzed with respect to not only internal class information, but
also method interactions. In this paper, we present a novel approach for
detecting God classes and decomposing their responsibilities based on the
semantics of methods and method interactions. We evaluate the approach using
JMeter v2.5.1 and the results are promising
Superconductivity and Physical Properties of CaPd2Ge2 Single Crystals
We present the superconducting and normal state properties of CaPd2Ge2 single
crystal investigated by magnetic susceptibility \chi, isothermal magnetization
M, heat capacity C_p, in-plane electrical resistivity \rho and London
penetration depth \lambda versus temperature T and magnetic field H
measurements. Bulk superconductivity is inferred from the \rho(T) and C_p(T)
data. The \rho(T) data exhibit metallic behavior and undergoes a
superconducting transition with T_c onset = 1.98 K and zero resistivity state
at T_c 0 = 1.67 K. The \chi(T) reveal the onset of superconductivity at 2.0 K.
For T>2.0 K, the \chi(T) and M(H) are weakly anisotropic paramagnetic with
\chi_ab > \chi_c. The C_p(T) confirm the bulk superconductivity below T_c =
1.69(3) K. The superconducting state electronic heat capacity is analyzed
within the framework of a single-band \alpha-model of BCS superconductivity and
various normal and superconducting state parameters are estimated. Within the
\alpha-model, the C_p(T) data and the ab plane \lambda(T) data consistently
indicate a moderately anisotropic s-wave gap with \Delta(0)/k_B T_c ~ 1.6,
somewhat smaller than the BCS value of 1.764. The relationship of the heat
capacity jump at T_c and the penetration depth measurement to the anisotropy in
the s-wave gap is discussed.Comment: 12 pages, 9 figures, 2 Tables; Submitted to PR
Easily Adaptable Complexity Measure for Finite Time Series
We present a complexity measure for any finite time series. This measure has
invariance under any monotonic transformation of the time series, has a degree
of robustness against noise, and has the adaptability of satisfying almost all
the widely accepted but conflicting criteria for complexity measurements.
Surprisingly, the measure is developed from Kolmogorov complexity, which is
traditionally believed to represent only randomness and to satisfy one
criterion to the exclusion of the others. For familiar iterative systems, our
treatment may imply a heuristic approach to transforming symbolic dynamics into
permutation dynamics and vice versa.Comment: 15 page, 3 figures, 1 table; modifications making cruicial points
clearer and improve readibility; had been completely rewritte
Fundamental Discreteness Limitations of Cosmological N-Body Clustering Simulations
We explore some of the effects that discreteness and two-body scattering may
have on N-body simulations with ``realistic'' cosmological initial conditions.
We use an identical subset of particles from the initial conditions for a
Particle-Mesh (PM) calculation as the initial conditions for a variety
PM and Tree code runs. We investigate the effect of mass resolution (the
mean interparticle separation) since most ``high resolution'' codes only have
high resolution in gravitational force. The phase-insensitive two--point
statistics, such as the power spectrum (autocorrelation) are somewhat affected
by these variations, but phase-sensitive statistics show greater differences.
Results converge at the mean interparticle separation scale of the lowest
mass-resolution code. As more particles are added, but the force resolution is
held constant, the PM and the Tree runs agree more and more strongly with
each other and with the PM run which had the same initial conditions. This
shows high particle density is necessary for correct time evolution, since many
different results cannot all be correct. However, they do not so converge to a
PM run which continued the fluctuations to small scales. Our results show that
ignoring them is a major source of error on comoving scales of the missing
wavelengths. This can be resolved by putting in a high particle density. Since
the codes never agree well on scales below the mean comoving interparticle
separation, we find little justification for quantitative predictions on this
scale. Some measures vary by 50%, but others can be off by a factor of three or
more. Our results suggest possible problems with the density of galaxy halos,
formation of early generation objects such as QSO absorber clouds, etc.Comment: Revised version to be published in Astrophysical Journal. One figure
changed; expanded discussion, more information on code parameters. Latex, 44
pages, including 19 figures. Higher resolution versions of Figures 10-15
available at: ftp://kusmos.phsx.ukans.edu/preprints/nbod
- …