8,878 research outputs found
Bridging the Gap between Enumerative and Symbolic Model Checkers
We present a method to perform symbolic state space generation for languages with existing enumerative state generators. The method is largely independent from the chosen modelling language. We validated this on three different types of languages and tools: state-based languages (PROMELA), action-based process algebras (muCRL, mCRL2), and discrete abstractions of ODEs (Maple).\ud
Only little information about the combinatorial structure of the\ud
underlying model checking problem need to be provided. The key enabling data structure is the "PINS" dependency matrix. Moreover, it can be provided gradually (more precise information yield better results).\ud
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Second, in addition to symbolic reachability, the same PINS matrix contains enough information to enable new optimizations in state space generation (transition caching), again independent from the chosen modelling language. We have also based existing optimizations, like (recursive) state collapsing, on top of PINS and hint at how to support partial order reduction techniques.\ud
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Third, PINS allows interfacing of existing state generators to, e.g., distributed reachability tools. Thus, besides the stated novelties, the method we propose also significantly reduces the complexity of building modular yet still efficient model checking tools.\ud
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Our experiments show that we can match or even outperform existing tools by reusing their own state generators, which we have linked into an implementation of our ideas
Characterisation of collaborative decision making processes
This paper deals with the collaborative decision making induced or facilitated by Information and Communication Technologies (ICTs) and their impact on decisional systems. After presenting the problematic, we analyse the collaborative decision making and define the concepts related to the conditions and forms of collaborative work. Then, we explain the mechanisms of collaborative decision making with the specifications and general conditions of collaboration using the modelling formalism of the GRAI method. Each specification associated to the reorganisation of the decisional system caused by the collaboration is set to the notion of decision-making centre. Finally, we apply this approach to the e-maintenance field, strongly penetrated by the ICTs, where collaborations are usual. We show that the identified specifications allow improving the definition and the management of collaboration in e-maintenance
A multilevel evolutionary algorithm for optimizing numerical functions
This is a study on the effects of multilevel selection (MLS) theory in optimizing numerical functions. Based on this theory, a Multilevel Evolutionary Optimization algorithm (MLEO) is presented. In MLEO, a species is subdivided in cooperative populations and then each population is subdivided in groups, and evolution occurs at two levels so called individual and group levels. A fast population dynamics occurs at individual level. At this level, selection occurs among individuals of the same group. The popular genetic operators such as mutation and crossover are applied within groups. A slow population dynamics occurs at group level. At this level, selection happens among groups of a population. The group level operators such as regrouping, migration, and extinction-colonization are applied among groups. In regrouping process, all the groups are mixed together and then new groups are formed. The migration process encourages an individual to leave its own group and move to one of its neighbour groups. In extinction-colonization process, a group is selected as extinct, and replaced by offspring of a colonist group. In order to evaluate MLEO, the proposed algorithms were used for optimizing a set of well known numerical functions. The preliminary results indicate that the MLEO theory has positive effect on the evolutionary process and provide an efficient way for numerical optimization
A story about standardization for design of glass works
This contribution attempts to give an overview of the European standardization framework which is related to the design and calculation of glass works in buildings. The different work levels, institutions, technical committees and workgroups, and the various types of documents and their statute will be introduced, explaining the difference between draft, experimental and final standards, between harmonized, support and design standards, the general and particular meaning of harmonization and implementation. The standardization framework is explained firstly from the point of view of European standardization policy and history, and secondly regarding the standardization framework in Belgium. In particular, an attempt is made to highlight some particularities existing in harmonization efforts of design methods and codes for glass works
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Information technology: futurism, corporations and the state
The significance of information technology (IT)' lies in the breadth of its potential impact on society: on work, communications, political processes, education and entertainment. It offers not just the possibility, in the current economic crisis, of restructuring work in order to gain greater control over that process the better to increase productivity, but also the possibility of a new cycle of growth in both capital and consumer goods, facilitating the restructuring of modes of consumption and the strengthening and recomposition of capital over patterns of leisure, communication and entertainment
Photoemission Beyond the Sudden Approximation
The many-body theory of photoemission in solids is reviewed with emphasis on
methods based on response theory. The classification of diagrams into loss and
no-loss diagrams is discussed and related to Keldysh path-ordering
book-keeping. Some new results on energy losses in valence-electron
photoemission from free-electron-like metal surfaces are presented. A way to
group diagrams is presented in which spectral intensities acquire a
Golden-Rule-like form which guarantees positiveness. This way of regrouping
should be useful also in other problems involving spectral intensities, such as
the problem of improving the one-electron spectral function away from the
quasiparticle peak.Comment: 18 pages, 11 figure
Anomalous relaxation kinetics of biological lattice-ligand binding models
We discuss theoretical models for the cooperative binding dynamics of ligands
to substrates, such as dimeric motor proteins to microtubules or more extended
macromolecules like tropomyosin to actin filaments. We study the effects of
steric constraints, size of ligands, binding rates and interaction between
neighboring proteins on the binding dynamics and binding stoichiometry.
Starting from an empty lattice the binding dynamics goes, quite generally,
through several stages. The first stage represents fast initial binding closely
resembling the physics of random sequential adsorption processes. Typically
this initial process leaves the system in a metastable locked state with many
small gaps between blocks of bound molecules. In a second stage the gaps
annihilate slowly as the ligands detach and reattach. This results in an
algebraic decay of the gap concentration and interesting scaling behavior. Upon
identifying the gaps with particles we show that the dynamics in this regime
can be explained by mapping it onto various reaction-diffusion models. The
final approach to equilibrium shows some interesting dynamic scaling
properties. We also discuss the effect of cooperativity on the equilibrium
stoichiometry, and their consequences for the interpretation of biochemical and
image reconstruction results.Comment: REVTeX, 20 pages, 17 figures; review, to appear in Chemical Physics;
v2: minor correction
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