1,064,553 research outputs found
Strategies for Parallel Markup
Cross-referenced parallel markup for mathematics allows the combination of
both presentation and content representations while associating the components
of each. Interesting applications are enabled by such an arrangement, such as
interaction with parts of the presentation to manipulate and querying the
corresponding content, and enhanced search indexing. Although the idea of such
markup is hardly new, effective techniques for creating and manipulating it are
more difficult than it appears. Since the structures and tokens in the two
formats often do not correspond one-to-one, decisions and heuristics must be
developed to determine in which way each component refers to and is referred to
by components of the other representation. Conversion between fine and coarse
grained parallel markup complicates ID assignments. In this paper, we will
describe the techniques developed for \LaTeXML, a \TeX/\LaTeX to XML converter,
to create cross-referenced parallel MathML. While we do not yet consider
\LaTeXML's content MathML to be useful, the current effort is a step towards
that continuing goal
Data fragmentation for parallel transitive closure strategies
Addresses the problem of fragmenting a relation to make the parallel computation of the transitive closure efficient, based on the disconnection set approach. To better understand this design problem, the authors focus on transportation networks. These are characterized by loosely interconnected clusters of nodes with a high internal connectivity rate. Three requirements that have to be fulfilled by a fragmentation are formulated, and three different fragmentation strategies are presented, each emphasizing one of these requirements. Some test results are presented to show the performance of the various fragmentation strategie
Parallel Evaluation of Multi-join Queries
A number of execution strategies for parallel evaluation of multi-join queries have been proposed in the literature. In this paper we give a comparative performance evaluation of four execution strategies by implementing all of them on the same parallel database system, PRISMA/DB. Experiments have been done up to 80 processors. These strategies, coming from the literature, are named: Sequential Parallel, Synchronous Execution, Segmented Right-Deep, and Full Parallel. Based on the experiments clear guidelines are given when to use which strategy.
This is an extended abstract; the full paper appeared in Proc. ACM SIGMOD'94, Minneapolis, Minnesota, May 24–27, 199
Minimization Strategies for Maximally Parallel Multiset Rewriting Systems
Maximally parallel multiset rewriting systems (MPMRS) give a convenient way
to express relations between unstructured objects. The functioning of various
computational devices may be expressed in terms of MPMRS (e.g., register
machines and many variants of P systems). In particular, this means that MPMRS
are computationally complete; however, a direct translation leads to quite a
big number of rules. Like for other classes of computationally complete
devices, there is a challenge to find a universal system having the smallest
number of rules. In this article we present different rule minimization
strategies for MPMRS based on encodings and structural transformations. We
apply these strategies to the translation of a small universal register machine
(Korec, 1996) and we show that there exists a universal MPMRS with 23 rules.
Since MPMRS are identical to a restricted variant of P systems with antiport
rules, the results we obtained improve previously known results on the number
of rules for those systems.Comment: This article is an improved version of [1
The JStar language philosophy
This paper introduces the JStar parallel programming language, which is a Java-based declarative language aimed at discouraging sequential programming, en-couraging massively parallel programming, and giving the compiler and runtime maximum freedom to try alternative parallelisation strategies. We describe the execution semantics and runtime support of the language, several optimisations and parallelism strategies, with some benchmark results
Particle methods parallel implementations by GP-GPU strategies
This paper outlines the problems found in the parallelization of SPH (Smoothed Particle Hydrodynamics) algorithms using Graphics Processing Units. Different results of some parallel GPU implementations in terms of the speed-up and the scalability compared to the CPU sequential codes are shown. The most problematic stage in the GPU-SPH algorithms is the one responsible for locating neighboring particles and building the vectors where this information is stored, since these specific algorithms raise many dificulties for a data-level parallelization. Because of the fact that the neighbor location using linked lists does not show enough data-level parallelism, two new approaches have been pro- posed to minimize bank conflicts in the writing and subsequent reading of the neighbor lists. The first strategy proposes an efficient coordination between CPU-GPU, using GPU algorithms for those stages that allow a straight forward parallelization, and sequential CPU algorithms for those instructions that involve some kind of vector reduction. This coordination provides a relatively orderly reading of the neighbor lists in the interactions stage, achieving a speed-up factor of x47 in this stage. However, since the construction of the neighbor lists is quite expensive, it is achieved an overall speed-up of x41. The second strategy seeks to maximize the use of the GPU in the neighbor's location process by executing a specific vector sorting algorithm that allows some data-level parallelism. Al- though this strategy has succeeded in improving the speed-up on the stage of neighboring location, the global speed-up on the interactions stage falls, due to inefficient reading of the neighbor vectors. Some changes to these strategies are proposed, aimed at maximizing the computational load of the GPU and using the GPU texture-units, in order to reach the maximum speed-up for such codes. Different practical applications have been added to the mentioned GPU codes. First, the classical dam-break problem is studied. Second, the wave impact of the sloshing fluid contained in LNG vessel tanks is also simulated as a practical example of particle method
Digital Quantum Estimation
Quantum Metrology calculates the ultimate precision of all estimation
strategies, measuring what is their root mean-square error (RMSE) and their
Fisher information. Here, instead, we ask how many bits of the parameter we can
recover, namely we derive an information-theoretic quantum metrology. In this
setting we redefine "Heisenberg bound" and "standard quantum limit" (the usual
benchmarks in quantum estimation theory), and show that the former can be
attained only by sequential strategies or parallel strategies that employ
entanglement among probes, whereas parallel-separable strategies are limited by
the latter. We highlight the differences between this setting and the
RMSE-based one.Comment: 5 pages+5 supplementary informatio
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