88 research outputs found
The Bottom-Up Position Tree Automaton, the Father Automaton and their Compact Versions
The conversion of a given regular tree expression into a tree automaton has
been widely studied. However, classical interpretations are based upon a
Top-Down interpretation of tree automata. In this paper, we propose new
constructions based on the Gluskov's one and on the one of Ilie and Yu one
using a Bottom-Up interpretation. One of the main goals of this technique is to
consider as a next step the links with deterministic recognizers, consideration
that cannot be performed with classical Top-Down approaches. Furthermore, we
exhibit a method to factorize transitions of tree automata and show that this
technique is particularly interesting for these constructions, by considering
natural factorizations due to the structure of regular expression.Comment: extended version of a paper accepted at CIAA 201
A General Framework for the Derivation of Regular Expressions
The aim of this paper is to design a theoretical framework that allows us to
perform the computation of regular expression derivatives through a space of
generic structures. Thanks to this formalism, the main properties of regular
expression derivation, such as the finiteness of the set of derivatives, need
only be stated and proved one time, at the top level. Moreover, it is shown how
to construct an alternating automaton associated with the derivation of a
regular expression in this general framework. Finally, Brzozowski's derivation
and Antimirov's derivation turn out to be a particular case of this general
scheme and it is shown how to construct a DFA, a NFA and an AFA for both of
these derivations.Comment: 22 page
Root-Weighted Tree Automata and their Applications to Tree Kernels
In this paper, we define a new kind of weighted tree automata where the
weights are only supported by final states. We show that these automata are
sequentializable and we study their closures under classical regular and
algebraic operations. We then use these automata to compute the subtree kernel
of two finite tree languages in an efficient way. Finally, we present some
perspectives involving the root-weighted tree automata
Some Combinatorial Operators in Language Theory
Multitildes are regular operators that were introduced by Caron et al. in
order to increase the number of Glushkov automata. In this paper, we study the
family of the multitilde operators from an algebraic point of view using the
notion of operad. This leads to a combinatorial description of already known
results as well as new results on compositions, actions and enumerations.Comment: 21 page
Construction of rational expression from tree automata using a generalization of Arden's Lemma
Arden's Lemma is a classical result in language theory allowing the
computation of a rational expression denoting the language recognized by a
finite string automaton. In this paper we generalize this important lemma to
the rational tree languages. Moreover, we propose also a construction of a
rational tree expression which denotes the accepted tree language of a finite
tree automaton
State complexity of catenation combined with a boolean operation: a unified approach
In this paper we study the state complexity of catenation combined with
symmetric difference. First, an upper bound is computed using some combinatoric
tools. Then, this bound is shown to be tight by giving a witness for it.
Moreover, we relate this work with the study of state complexity for two other
combinations: catenation with union and catenation with intersection. And we
extract a unified approach which allows to obtain the state complexity of any
combination involving catenation and a binary boolean operation
Bottom Up Quotients and Residuals for Tree Languages
In this paper, we extend the notion of tree language quotients to bottom-up
quotients. Instead of computing the residual of a tree language from top to
bottom and producing a list of tree languages, we show how to compute a set of
k-ary trees, where k is an arbitrary integer. We define the quotient formula
for different combinations of tree languages: union, symbol products,
compositions, iterated symbol products and iterated composition. These
computations lead to the definition of the bottom-up quotient tree automaton,
that turns out to be the minimal deterministic tree automaton associated with a
regular tree language in the case of the 0-ary trees
Multilinear representations of Free PROs
We describe a structure of PRO on hypermatrices. This structure allows us to
define multilinear representations of PROs and in particular of free Pros. As
an example of applications, we investigate the relations of the representations
of Pros with the theory of automata.Comment: 39 page
Etude d'implémentations MPI dans une grille de calcul
National audienceThis paper presents an evaluation on the GRID'5000 platform of four MPI implementation: MPICH2, MPICH-Madeleine, OpenMPI et GridMPI. The comparison is based on a simple pingpong and the NAS parallel benchmarks. We show that GridMPI has the best results with regards to performances on the Grid if the implementation is well tuned. This paper details which parameters should be tuned.De nos jours, les grappes de PC ou clusters sont souvent interconnectés par des réseaux longue-distance de manière à former une grille afin d'offrir à un grand nombre d'utilisateurs un nombre plus conséquent de ressources. MPI, la bibliothèque de communication la plus utilisée pour les applications parallèles, a été efficacement implémentée dans un contexte de clusters. Deux caractéristiques des grilles, les réseaux longue-distance et l'hétérogénéité des processeurs et des réseaux, posent la question de l'efficacité de MPI sur les grilles. Cet article présente une évaluation sur la grille de recherche française GRID'5000, de 4 implémentations récentes de MPI : MPICH2, MPICH-Madeleine, OpenMPI et GridMPI. La comparaison est basée sur un pingpong, les NAS Parallel Benchmarks. Nous mettons en évidence les différences de performance obtenues avec les 4 implé- mentations. GridMPI montre les meilleures performances. L'exécution d'applications MPI sur la grille peut être bénéfique à condition de régler finement certains paramètres des implémentations. Cet article détaille les para- mètres mis en jeu et leurs réglages
Comparison and tuning of MPI implementations in a grid context
Today, clusters are often interconnected by long distance networks within grids to offer a huge number of available ressources to a range of users. MPI, the standard communication library used to write parallel applications, has been implemented for clusters. Two main features of grids: long distance networks and technological heterogeneity, raise the question of MPI efficiency in grids. This report presents an evaluation of four recent MPI implementations (MPICH2, MPICH-Madeleine, OpenMPI and GridMPI) in the french research grid: Grid'5000. The comparison is based on the execution of pingpong, NAS Parallel Benchmarks and a real application in geophysics. We show that this implementations present performance differences. Executing MPI applications on the grid can be beneficial if the parameters are well tuned. The paper details the tuning required on each implementation to get the best performances
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