2,634 research outputs found
Upgrading Relational Legacy Data to eh Semantic Web
In this poster, we describe a framework composed of the R2O mapping language and the ODEMapster processor to upgrade relational legacy data to the Semantic Web. The framework is based on the declarative description of mappings between relational and ontology elements and the exploitation of such mapping descriptions by a generic processor capable of performing both massive and query driven data upgrade
Fund Finder: A case study of database-to-ontology mapping
The mapping between databases and ontologies is a basic problem when trying to "upgrade" deep web content to the semantic web. Our approach suggests the declarative definition of mappings as a way to achieve domain independency and reusability. A specific language (expressive enough to cover some real world mapping situations like lightly structured databases or not 1st normal form ones) is defined for this purpose. Along with this mapping description language, the ODEMapster processor is in charge of carrying out the effective instance data migration. We illustrate this by testing both the mappings definition and processor on a case study
R2O, an extensible and semantically based database-to-ontology mapping language
We present R2O, an extensible and declarative language to describe mappings between relational DB schemas and ontologies implemented in RDF(S) or OWL. R2O provides an extensible set of primitives with welldefined semantics. This language has been conceived expressive enough to cope with complex mapping cases arisen from situations of low similarity between the ontology and the DB models
Data envelopment analysis efficiency of public services: bootstrap simultaneous confidence region
Public services, such as higher education, medical services, libraries or public administration offices, provide services to their customers. To obtain opinion-satisfaction indices of customers, it would be necessary to survey all the customers of the service (census), which is impossible. What is possible is to estimate the indices by surveying a random customer sample. The efficiency obtained with the classic data envelopment analysis models, considering the opinion indices of the customers of the public service as output data estimated with a user sample, will be an estimation of the obtained efficiency if the census is available. This paper proposes a bootstrap methodology to build a confidence region to simultaneously estimate the population data envelopment analysis efficiency score vector of a set of public service-producing units, with a fixed confidence level and using deterministic input data and estimated customer opinion indices as output data. The usefulness of the result is illustrated by describing a case study comparing the efficiency of libraries.Peer Reviewe
Compound orbits break-up in constituents: an algorithm
In this paper decomposition of periodic orbits in bifurcation diagrams are
derived in unidimensional dynamics system , being an
unimodal function. We proof a theorem which states the necessary and sufficient
conditions for the break-up of compound orbits in their simpler constituents. A
corollary to this theorem provides an algorithm for the computation of those
orbits. This process closes the theoretical framework initiated in (Physica D,
239:1135--1146, 2010)
Supersymmetric Double Field Theory and the generalized Kerr-Schild Ansatz
We construct the supersymmetric extension of the
generalized Kerr-Schild ansatz in the flux formulation of Double Field Theory.
We show that this ansatz is compatible with supersymmetry as
long as it is not written in terms of generalized null vectors. Supersymmetric
consistency is obtained through a set of conditions that imply linearity of the
generalized gravitino perturbation and unrestricted perturbations of the
generalized background dilaton and dilatino. As a final step we parametrize the
previous theory in terms of the field content of the low energy effective
-dimensional heterotic supergravity and we find that the perturbation of
the -dimensional vielbein, Kalb-Ramond field and gravitino can be written
in terms of a pair of null vectors, as expected.Comment: 34 pages. We include the gauge sector and applications considering
gaugino condensatio
Higher-derivative Heterotic Double Field Theory and Classical Double Copy
The generalized Kerr-Schild ansatz (GKSA) is a powerful tool for constructing
exact solutions in Double Field Theory (DFT). In this paper we focus in the
heterotic formulation of DFT, considering up to four-derivative terms in the
action principle, while the field content is perturbed by the GKSA. We study
the inclusion of the generalized version of the Green-Schwarz mechanism to this
setup, in order to reproduce the low energy effective heterotic supergravity
upon parametrization. This formalism reproduces higher-derivative heterotic
background solutions where the metric tensor and Kalb-Ramond field are
perturbed by a pair of null vectors. Next we study higher-derivative
contributions to the classical double copy structure. After a suitable
identification of the null vectors with a pair of gauge fields, the
dynamics is given by a pair of Maxwell equations plus higher derivative
corrections in agreement with the KLT relation.Comment: V2 includes: EOM's for fundamental fields (Sec. 4), explicit
construction of the spin-connection (Sec. 5) and we relax the ortogonality
condition for the null vectors (Sec. 6). We thank our anonymous JHEP referee
for the suggestion
Algorithms for Graph-Constrained Coalition Formation in the Real World
Coalition formation typically involves the coming together of multiple,
heterogeneous, agents to achieve both their individual and collective goals. In
this paper, we focus on a special case of coalition formation known as
Graph-Constrained Coalition Formation (GCCF) whereby a network connecting the
agents constrains the formation of coalitions. We focus on this type of problem
given that in many real-world applications, agents may be connected by a
communication network or only trust certain peers in their social network. We
propose a novel representation of this problem based on the concept of edge
contraction, which allows us to model the search space induced by the GCCF
problem as a rooted tree. Then, we propose an anytime solution algorithm
(CFSS), which is particularly efficient when applied to a general class of
characteristic functions called functions. Moreover, we show how CFSS can
be efficiently parallelised to solve GCCF using a non-redundant partition of
the search space. We benchmark CFSS on both synthetic and realistic scenarios,
using a real-world dataset consisting of the energy consumption of a large
number of households in the UK. Our results show that, in the best case, the
serial version of CFSS is 4 orders of magnitude faster than the state of the
art, while the parallel version is 9.44 times faster than the serial version on
a 12-core machine. Moreover, CFSS is the first approach to provide anytime
approximate solutions with quality guarantees for very large systems of agents
(i.e., with more than 2700 agents).Comment: Accepted for publication, cite as "in press
Labor demand and information technologies: evidence for Spain, 1980-2005
Utilizando la base de datos EU KLEMS, se contrasta la hipótesis de complementariedad entre habilidad y capital en los distintos sectores productivos en España en el periodo 1980-2005. Se analizan tres tipos de trabajadores clasificados según su nivel de habilidad sea alto, medio o bajo. Los activos de capital se van a clasificar entre activos TIC (tecnologÃas de la información y la comunicación) y activos no-TIC. La adquisición y el uso de activos TIC son costosos pero ha ido disminuyendo en el periodo en consideración en términos relativos a otros activos y al factor trabajo. El principal resultado que se obtiene es que existe un grado de sustituibilidad entre los trabajadores y los activos TIC a medida que la habilidad del trabajador va aumentando. De hecho, los activos TIC son muy complementarios con los trabajadores de alta habilidad. A lo largo del periodo analizado, la fracción de trabajadores con habilidad media y alta ha crecido un 21% y un 12%, respectivamente, en detrimento de los trabajadores de baja habilidad. Después de descomponer estos cambios, se descubre que existe un ajuste dentro de los sectores más que un ajuste del trabajo entre sectores.capital-skill complementarity, ICT, translog cost function, elasticity of substitution.
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