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See detailOmega-regular model checking
Boigelot, Bernard ULg; Legay, A.; Wolper, Pierre ULg

in Lecture Notes in Computer Science (2004), 2988

"Regular model checking" is the name of a family of techniques for analyzing infinite-state systems in which states are represented by words or trees, sets of states by finite automata on these objects ... [more ▼]

"Regular model checking" is the name of a family of techniques for analyzing infinite-state systems in which states are represented by words or trees, sets of states by finite automata on these objects, and transitions by finite automata operating on pairs of state encodings, i.e. finite-state transducers. In this context, the central problem is then to compute the iterative closure of a finite-state transducer. This paper addresses the use of regular model-checking like techniques for systems whose states are represented by infinite (omega) words. Its main motivation is to show the feasibility and usefulness of this approach through a combination of the necessary theoretical developments, implementation, and experimentation. The iteration technique that is used is adapted from recent work of the authors on the iteration of finite-word transducers. It proceeds by comparing successive elements of a sequence of approximations of the iteration, detecting an "increment" that is added to move from one approximation to the next, and extrapolating the sequence by allowing arbitrary repetitions of this increment. By restricting oneself to weak deterministic Buchi automata, and using a number of implementation optimizations, examples of significant size can be handled. The proposed transducer iteration technique can just as well be exploited to compute the closure of a given set of states by the transducer iteration, which has proven to be a very effective way of using the technique. Examples such as a leaking gas burner in which time is modeled by real variables have been handled completely within the automata-theoretic setting. [less ▲]

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See detailOmnipresent and Everlasting Imperialism: Race and Gender Oppression in Caryl Phillips's Cambridge and A Distant Shore
Gillet, Lucie ULg

in Ledent, Bénédicte; Tunca, Daria (Eds.) Caryl Phillips: Writing in the Key of Life (2010)

Detailed reference viewed: 113 (5 ULg)
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See detailOmongwaite, Na2Ca5(SO4)6.3H2O, a new mineral from recent salt lake deposits, Namibia
Mees, Florias; Hatert, Frédéric ULg; Rowe, R.

in Mineralogical Magazine (2008), 72

Detailed reference viewed: 33 (1 ULg)
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See detailOmtrek en oppervlakte van pixelfiguren
Bogaert, Jan ULg; Rousseau, R

in Wiskunde en Onderwijs (1999), 25

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See detailOmvang en samenstelling van het gemeenschappelijk vermogen
Leleu, Yves-Henri ULg

in Verbeke, A.; Buyssens, F.; Derycke, H. (Eds.) Estate planning - Vermogensplanning met effect bij leven: huwelijk en samenwoning (2004)

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See detailOn (Omega-)regular model checking
Legay, Axel; Wolper, Pierre ULg

in ACM Transactions on Computational Logic (2010), 12(1), 46

Checking infinite-state systems is frequently done by encoding infinite sets of states as regular languages. Computing such a regular representation of, say, the set of reachable states of a system ... [more ▼]

Checking infinite-state systems is frequently done by encoding infinite sets of states as regular languages. Computing such a regular representation of, say, the set of reachable states of a system requires acceleration techniques that can finitely compute the effect of an unbounded number of transitions. Among the acceleration techniques that have been proposed, one finds both specific and generic techniques. Specific techniques exploit the particular type of system being analyzed, for example, a system manipulating queues or integers, whereas generic techniques only assume that the transition relation is represented by a finite-state transducer, which has to be iterated. In this article, we investigate the possibility of using generic techniques in cases where only specific techniques have been exploited so far. Finding that existing generic techniques are often not applicable in cases easily handled by specific techniques, we have developed a new approach to iterating transducers. This new approach builds on earlier work, but exploits a number of new conceptual and algorithmic ideas, often induced with the help of experiments, that give it a broad scope, as well as good performances. [less ▲]

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See detailOn a "Mathematical Neo-Aristotelism" in Leibniz
Bouquiaux, Laurence ULg

in Self-Organisation and Emergence in Life Sciences, Springer, Dordrecht (2006)

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See detailOn a class of micromechanical damage models with initial stresses for geomaterials
Levasseur, Séverine ULg; Collin, Frédéric ULg; Charlier, Robert ULg et al

in Mechanics Research Communications (2010), 37

In this paper, we extend a class of micromechanical damage models by including initial stresses. The proposed approach is based on the solution of the Eshelby inhomogeneous inclusion problem in the ... [more ▼]

In this paper, we extend a class of micromechanical damage models by including initial stresses. The proposed approach is based on the solution of the Eshelby inhomogeneous inclusion problem in the presence of a prestress (in the matrix), adapted for elastic voided media. The closed form expression of the corresponding energy potential is used as the basis of various isotropic damage models corresponding to three standard homogenization schemes. These models are illustrated by considering isotropic tensile loadings with different initial stresses. Finally, still in the isotropic context, we provide an interpretation of the macroscopic damage model formulated by Halm-Dragon (1996) by briefly connecting it to the present study. [less ▲]

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See detailOn a fundamental structure of gene networks in living cells
Kravchenko-Balasha, Nataly; Levitzki, Alexander; Goldstein, Andrew et al

in Proceedings of the National Academy of Sciences of the United States of America (2012), 109(12), 4702-4707

Computers are organized into hardware and software. Using a theoretical approach to identify patterns in gene expression in a variety of species, organs, and cell types, we found that biological systems ... [more ▼]

Computers are organized into hardware and software. Using a theoretical approach to identify patterns in gene expression in a variety of species, organs, and cell types, we found that biological systems similarly are comprised of a relatively unchanging hardware-like gene pattern. Orthogonal patterns of software-like transcripts vary greatly, even among tumors of the same type from different individuals. Two distinguishable classes could be identified within the hardware-like component: those transcripts that are highly expressed and stable and an adaptable subset with lower expression that respond to external stimuli. Importantly, we demonstrate that this structure is conserved across organisms. Deletions of transcripts from the highly stable core are predicted to result in cell mortality. The approach provides a conceptual thermodynamic-like framework for the analysis of gene-expression levels and networks and their variations in diseased cells. [less ▲]

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See detailOn a general decomposition of the error of an approximate stress field in elasticity
Debongnie, Jean-François ULg; Beckers, Pierre ULg

in Computer Assisted Mechanics and Engineering Sciences [=CAMES] (2001), 8

The errors of finite element approximations are analysed in a general frame, which is completely independent from the way through which the approximate solution was obtained. It is found that the error ... [more ▼]

The errors of finite element approximations are analysed in a general frame, which is completely independent from the way through which the approximate solution was obtained. It is found that the error always admits decomposition in two terms, namely the equilibrium error and the compatibility error, which are orthogonal. Each of these admits upper and lower bound that can be computed in a post-processing scheme [less ▲]

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See detailOn a Lie Algebraic Characterization of Vector Bundles
Lecomte, Pierre ULg; Leuther, Thomas ULg; Zihindula Mushengezi, Elie ULg

in Symmetry, Integrability and Geometry: Methods and Applications [=SIGMA] (2012)

We prove that a vector bundle E -> M is characterized by the Lie algebra generated by all differential operators on E which are eigenvectors of the Lie derivative in the direction of the Euler vector ... [more ▼]

We prove that a vector bundle E -> M is characterized by the Lie algebra generated by all differential operators on E which are eigenvectors of the Lie derivative in the direction of the Euler vector field. Our result is of Pursell-Shanks type but it is remarkable in the sense that it is the whole f ibration that is characterized here. The proof relies on a theorem of [Lecomte P., J. Math. Pures Appl. (9) 60 (1981), 229{239] and inherits the same hypotheses. In particular, our characterization holds only for vector bundles of rank greater than 1. [less ▲]

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See detailOn a modified bilinear law to model bit/rock interaction in percussive drilling
Depouhon, Alexandre ULg; Denoël, Vincent ULg; Detournay, Emmanuel

in Proceedings of the Nonlinear Dynamics in Engineering Conference (2013, August 21)

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See detailOn a new species of Gregarina to be called Gregarina gigentea
Van Beneden, Édouard ULg

in Quarterly Journal of Microscopical Science (The) (1870), 2(10), 51-59

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See detailOn a purely lagrangian formulation of sloshing and fluid-induced vibrations of tanks
Debongnie, Jean-François ULg

in Computer Methods in Applied Mechanics & Engineering (1986), 58(1), 1-18

A general variational principle for fluid-structure interactions is obtained from a purely Lagrangian point of view, thus avoiding any difficulty at the fluid-structure interaction. This rather general ... [more ▼]

A general variational principle for fluid-structure interactions is obtained from a purely Lagrangian point of view, thus avoiding any difficulty at the fluid-structure interaction. This rather general variational principle is shown to degenerate, when suitable restrictions are made, in two known formulations, whose range of applicability is defined with the aid of three nondimensional numbers. [less ▲]

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See detailOn a q-analogue of the spin-orbit coupling
Micu, M.; Stancu, Floarea ULg

in Journal of Physics : A Mathematical & General (2000), A33

Based on the tensor method, a $q$-analogue of the spin-orbit coupling is introduced in a $q$-deformed Schr\" odinger equation, previously derived for a central potential. Analytic expressions for the ... [more ▼]

Based on the tensor method, a $q$-analogue of the spin-orbit coupling is introduced in a $q$-deformed Schr\" odinger equation, previously derived for a central potential. Analytic expressions for the matrix elements of the representations $j = \ell \pm 1/2$ are derived. The spectra of the harmonic oscillator and the Coulomb potential are calculated numerically as a function of the deformation parameter, without and with the spin-orbit coupling. The harmonic oscillator spectrum presents strong analogies with the bound spectrum of an Woods-Saxon potential customarily used in nuclear physics. The Coulomb spectrum simulates relativistic effects. The addition of the spin-orbit coupling reinforces this picture. [less ▲]

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See detailOn a three-body confinement force in hadron spectroscopy
Pepin, S.; Stancu, Floarea ULg

in Physical Review. D : Particles and Fields (2002), D65

Recently it has been argued that a three-body colour confinement interaction can affect the stability condition of a three-quark system and the spectrum of a tetraquark described by any constituent quark ... [more ▼]

Recently it has been argued that a three-body colour confinement interaction can affect the stability condition of a three-quark system and the spectrum of a tetraquark described by any constituent quark model. Here we discuss the role of a three-body colour confinement interaction in a simple quark model and present some of its implications for the spectra of baryons, tetraquarks and six-quark systems. [less ▲]

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See detailOn an Extended Irreversible Thermodynamic description of transient heat conduction in nano structures
Lebon, Georgy ULg; Dauby, Pierre ULg; Grmela, M.

in Proceedings of the 2d IEEES Conference (2005, July)

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See detailOn angle references in long-term time-domain simulations
Fabozzi, Davide ULg; Van Cutsem, Thierry ULg

in IEEE Transactions on Power Systems (2011), 26(1), 483-484

Abstract—In power system dynamic models the complex network equations and the various phasors are projected onto reference axes. After a short critical review of commonly chosen reference axes, this ... [more ▼]

Abstract—In power system dynamic models the complex network equations and the various phasors are projected onto reference axes. After a short critical review of commonly chosen reference axes, this letter proposes to use the center-of-inertia at the previous integration time step. This approach is shown to combine the advantages of the center-of-inertia with a sparser Jacobian structure and an easier handling of network splits. [less ▲]

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See detailOn being enrolled as an "embedded humanist" with nanotechnologists
Thoreau, François ULg

Conference (2012, January 13)

Detailed reference viewed: 29 (1 ULg)
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See detailOn BGP Communities
Donnet, Benoît ULg; Bonaventure, Olivier

in Computer Communication Review (2008), 38(2),

This paper focuses on BGP communities, a particular BGP attribute that has not yet been extensively studied by the research community. It allows an operator to group destinations in a single entity to ... [more ▼]

This paper focuses on BGP communities, a particular BGP attribute that has not yet been extensively studied by the research community. It allows an operator to group destinations in a single entity to which the same routing decisions might be applied. In this paper, we show that the usage of this attribute has increased and that it also contributes to routing table growth. In addition, we propose a taxonomy of BGP community attributes to allow operators to better document their communities. We further manually collect information on BGP communities and tag it according to our taxonomy. We show that a large propor- tion of the BGP communities are used for traffic engineering purposes. [less ▲]

Detailed reference viewed: 11 (0 ULg)