23,240 research outputs found
Static and dynamic semantics of NoSQL languages
We present a calculus for processing semistructured data that spans
differences of application area among several novel query languages, broadly
categorized as "NoSQL". This calculus lets users define their own operators,
capturing a wider range of data processing capabilities, whilst providing a
typing precision so far typical only of primitive hard-coded operators. The
type inference algorithm is based on semantic type checking, resulting in type
information that is both precise, and flexible enough to handle structured and
semistructured data. We illustrate the use of this calculus by encoding a large
fragment of Jaql, including operations and iterators over JSON, embedded SQL
expressions, and co-grouping, and show how the encoding directly yields a
typing discipline for Jaql as it is, namely without the addition of any type
definition or type annotation in the code
Hypersensitivity and chaos signatures in the quantum baker's maps
Classical chaotic systems are distinguished by their sensitive dependence on
initial conditions. The absence of this property in quantum systems has lead to
a number of proposals for perturbation-based characterizations of quantum
chaos, including linear growth of entropy, exponential decay of fidelity, and
hypersensitivity to perturbation. All of these accurately predict chaos in the
classical limit, but it is not clear that they behave the same far from the
classical realm. We investigate the dynamics of a family of quantizations of
the baker's map, which range from a highly entangling unitary transformation to
an essentially trivial shift map. Linear entropy growth and fidelity decay are
exhibited by this entire family of maps, but hypersensitivity distinguishes
between the simple dynamics of the trivial shift map and the more complicated
dynamics of the other quantizations. This conclusion is supported by an
analytical argument for short times and numerical evidence at later times.Comment: 32 pages, 6 figure
Distributed Holistic Clustering on Linked Data
Link discovery is an active field of research to support data integration in
the Web of Data. Due to the huge size and number of available data sources,
efficient and effective link discovery is a very challenging task. Common
pairwise link discovery approaches do not scale to many sources with very large
entity sets. We here propose a distributed holistic approach to link many data
sources based on a clustering of entities that represent the same real-world
object. Our clustering approach provides a compact and fused representation of
entities, and can identify errors in existing links as well as many new links.
We support a distributed execution of the clustering approach to achieve faster
execution times and scalability for large real-world data sets. We provide a
novel gold standard for multi-source clustering, and evaluate our methods with
respect to effectiveness and efficiency for large data sets from the geographic
and music domains
Quantum random walks without walking
Quantum random walks have received much interest due to their non-intuitive
dynamics, which may hold the key to a new generation of quantum algorithms.
What remains a major challenge is a physical realization that is experimentally
viable and not limited to special connectivity criteria. We present a scheme
for walking on arbitrarily complex graphs, which can be realized using a
variety of quantum systems such as a BEC trapped inside an optical lattice.
This scheme is particularly elegant since the walker is not required to
physically step between the nodes; only flipping coins is sufficient.Comment: 12 manuscript pages, 3 figure
Supporting process reuse in PROMENADE
Process reuse (the ability to construct new processes by assembling already built ones) and process harvesting (the ability to build generic processes
that may be further reused, from existing ones) are two crucial issues in
process technology. Both activities involve defining a set of mechanisms,
like abstraction, adaptation, composition, etc. which are appropriate to
achieve their goals. In this report, we define a general framework to
process reuse and harvesting that proposes a complete set of mechanisms to
deal with both activities. This general framework is particularized to the
context of a process modelling language to model software processes, called
PROMENADE. A definition of the identified reuse and harvesting mecha-nisms
is proposed in the context of PROMENADE. Finally, two process reuse case
studies which composes various reuse mechanisms are presented.Postprint (published version
- …