2001
Autores
Rocha, R; Silva, FMA; Costa, VS;
Publicação
Logic Programming, 17th International Conference, ICLP 2001, Paphos, Cyprus, November 26 - December 1, 2001, Proceedings
Abstract
Tabling is an implementation technique that improves the declarativeness and expressiveness of Prolog by reusing solutions to goals. Quite a few interesting applications of tabling have been developed in the last few years, and several are by nature non-deterministic. This raises the question of whether parallel search techniques can be used to improve the performance of tabled applications. In this work we demonstrate that the mechanisms proposed to parallelize search in the context of SLD resolution naturally generalize to parallel tabled computations, and that resulting systems can achieve good performance on multi-processors. To do so, we present the OPT Yap parallel engine. In our system individual SLG engines communicate data through stack copying. Completion is detected through a novel parallel completion algorithm that builds upon the data structures proposed for or-parallelism. Scheduling is simplified by building on previous research on or-parallelism. We show initial performance results for our implementation. Our best result is for an actual application, model checking, where we obtain linear speedups. © Springer-Verlag Berlin Heidelberg 2001.
2001
Autores
Lopes, L; Vasconcelos, VT; Silva, F;
Publicação
IEEE TRANSACTIONS ON COMPUTERS
Abstract
This paper presents a multithreaded abstract machine for the TyCO process calculus. We argue that process calculi provide a powerful framework to reason about fine-grained parallel computations. They allow for the construction of formally verifiable systems on which to base high-level programming idioms, combined with efficient compilation schemes into multithreaded architectures.
2001
Autores
Amado, N; Gama, J; Silva, FMA;
Publicação
Progress in Artificial Intelligence, Knowledge Extraction, Multi-agent Systems, Logic Programming and Constraint Solving, 10th Portuguese Conference on Artificial Intelligence, EPIA 2001, Porto, Portugal, December 17-20, 2001, Proceedings
Abstract
In the fields of data mining and machine learning the amount of data available for building classifiers is growing very fast. Therefore, there is a great need for algorithms that are capable of building classifiers from very-large datasets and, simultaneously, being computationally efficient and scalable. One possible solution is to employ parallelism to reduce the amount of time spent in building classifiers from very-large datasets and keeping the classification accuracy. This work first overviews some strategies for implementing decision tree construction algorithms in parallel based on techniques such as task parallelism, data parallelism and hybrid parallelism. We then describe a new parallel implementation of the C4.5 decision tree construction algorithm. Even though the implementation of the algorithm is still in final development phase, we present some experimental results that can be used to predict the expected behavior of the algorithm. © Springer-Verlag Berlin Heidelberg 2001.
2001
Autores
Castro, LF; Costa, VS;
Publicação
Logic Programming, 17th International Conference, ICLP 2001, Paphos, Cyprus, November 26 - December 1, 2001, Proceedings
Abstract
2000
Autores
Lopes, L; Figueira, A; Silva, F; Vasconcelos, VT;
Publicação
CLUSTER 2000: IEEE INTERNATIONAL CONFERENCE ON CLUSTER COMPUTING, PROCEEDINGS
Abstract
We propose a programming model for distributed concurrent systems with mobile objects in the context of a process calculus. Code mobility is induced by lexical scoping on names. Objects and messages migrate towards the site where their prefixes are lexically bound. Class definitions, on the other hand, are downloaded from the site where they are defined and are instantiated locally upon arrival. We provide several programming examples to demonstrate the expressiveness of the model. Finally, based on this model we describe an. architecture for a run-time system supporting concurrent, distributed computations and code mobility.
2000
Autores
Lopes, L; Silva, F; Vasconcelos, VT;
Publicação
2000 INTERNATIONAL CONFERENCE ON PARALLEL ARCHITECTURES AND COMPILATION TECHNIQUES, PROCEEDINGS
Abstract
This paper presents a multithreaded abstract machine for the TyCO process calculus. We argue that process calculi provide a powerful framework to reason about fine grained parallel computations. They allow the construction of formally verifiable systems on which to base high-level programming idioms, combined with efficient compilation schemes into multithreaded architectures.
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