Logic Programming Approaches for Representing and Solving Constraint Satisfaction Problems: A Comparison

Many logic programming based approaches can be used to describe and solve combinatorial search problems. On the one hand there is constraint logic programming which computes a solution as an answer substitution to a query containing the variables of the constraint satisfaction problem. On the other hand there are systems based on stable model semantics, abductive systems, and first order logic model generators which compute solutions as models of some theory. This paper compares these different approaches from the point of view of knowledge representation (how declarative are the programs) and from the point of view of performance (how good are they at solving typical problems).Comment: 15 pages, 3 eps-figure

Knowledge Compilation of Logic Programs Using Approximation Fixpoint Theory

To appear in Theory and Practice of Logic Programming (TPLP), Proceedings of ICLP 2015 Recent advances in knowledge compilation introduced techniques to compile \emph{positive} logic programs into propositional logic, essentially exploiting the constructive nature of the least fixpoint computation. This approach has several advantages over existing approaches: it maintains logical equivalence, does not require (expensive) loop-breaking preprocessing or the introduction of auxiliary variables, and significantly outperforms existing algorithms. Unfortunately, this technique is limited to \emph{negation-free} programs. In this paper, we show how to extend it to general logic programs under the well-founded semantics. We develop our work in approximation fixpoint theory, an algebraical framework that unifies semantics of different logics. As such, our algebraical results are also applicable to autoepistemic logic, default logic and abstract dialectical frameworks

Layered Mobility Model Architecture - LEMMA

This paper presents the generic layered architecture for mobility models (LEMMA), which can be used to construct a wide variety of mobility models, including the majority of models used in wireless network simulations. The fundamental components of the architecture are described and analyzed, in addition to its benefits. One of the core principles stipulates that each mobility model is divided in five distinct layers that communicate via interfaces. This allows their easy replacement and recombination, which we support by reviewing 19 layers that can form 480 different mobility models. Some of the advanced features provided by the architecture are also discussed, such as layer aggregation, and creation of hybrid and group mobility models. Finally, some of the numerous existing studies of the different layers are presented

The KB paradigm and its application to interactive configuration

The knowledge base paradigm aims to express domain knowledge in a rich formal language, and to use this domain knowledge as a knowledge base to solve various problems and tasks that arise in the domain by applying multiple forms of inference. As such, the paradigm applies a strict separation of concerns between information and problem solving. In this paper, we analyze the principles and feasibility of the knowledge base paradigm in the context of an important class of applications: interactive configuration problems. In interactive configuration problems, a configuration of interrelated objects under constraints is searched, where the system assists the user in reaching an intended configuration. It is widely recognized in industry that good software solutions for these problems are very difficult to develop. We investigate such problems from the perspective of the KB paradigm. We show that multiple functionalities in this domain can be achieved by applying different forms of logical inferences on a formal specification of the configuration domain. We report on a proof of concept of this approach in a real-life application with a banking company. To appear in Theory and Practice of Logic Programming (TPLP).Comment: To appear in Theory and Practice of Logic Programming (TPLP

Charging electric vehicles in the smart city: A survey of economy-driven approaches

International audienceElectric vehicles (EVs), as their penetration increases, do not only challenge the sustainability of the power grid but also stimulate and promote its upgrading. Indeed, EVs can actively reinforce the development of the smart grid if their charging processes are properly coordinated through two-way communications, possibly benefiting all types of actors. Because grid systems involve a large number of actors with nonaligned objectives, we focus on the economic and incentive aspects, where each actor behaves in its own interest. We indeed believe that the market structure will directly impact the actors' behaviors, and as a result, the total benefits that the presence of EVs can earn in the society, hence the need for a careful design. This survey provides an overview of economic models considering unidirectional energy flows and bidirectional energy flows, i.e., with EVs temporarily providing energy to the grid. We describe and compare the main approaches, summarize the requirements on the supporting communication systems, and propose a classification to highlight the most important results and lacks

Neonatal urinoma associated with ascites in a newborn with a solitary kidney

Fetal urinomas are often diagnosed in prenatal ultrasonography. The etiology is usually an obstructive uropathy leading to hydronephrosis and increased intrarenal pressure putting future kidney function at risk. Rupture of pyelocaliceal system in such cases may lead to retroperitoneal urinoma or urinary ascites, sepsis, uraemia, and acute renal failure. On the other hand, this may serve as “pop-off valve” mechanism decreasing intrarenal pressure and protecting from definitive kidney function loss. We present a case of a newborn girl with a retroperitoneal urinoma, ascites, uraemia, and obstruction of a solitary right kidney, which was successfully treated minimally invasively through peritoneal and retroperitoneal drainage and intubation of the right ureter with a DJ stent shortly after birth

Semantics of logic programs with aggregates

nrpages: 152 + Xstatus: publishe

Mobility models for wireless networks

Depuis quelques années, les réseaux sans fil connaissent un véritable engouement aussi bien dans le domaine civil que militaire. Les spécificités de ce type de réseaux ainsi que la grande variété de scénarios d'application ont fait émerger de nouveaux défis dans la recherche, notamment dans le domaine des réseaux informatiques. L'une des principales raisons du succès de ce type de réseau réside dans la possibilité de se déplacer tout en continuant à bénéficier des services offerts par le réseau. La modélisation des déplacements est par conséquent devenue l'une des thématiques de recherche de premier plan dans le domaine des réseaux sans fil. Dans cette thèse, nous avons étudié les différents aspects et caractéristiques qui font qu un modèle de mobilité est valide pour l'étude des réseaux WLAN, MANET, VANET, DTN et cellulaires. Nos travaux nous ont amené à la proposition d'une nouvelle architecture appelée LEMMA. Cette architecture facilite la création, la modification, la validation et la vérification des modèles de mobilité. En outre, nous avons prouvé les propriétés mathématiques de notre architecture et nous avons démontré empiriquement et formellement que tout modèle de mobilité peut être représenté avec LEMMA. Afin d'établir une correspondance avec l'intuition qu un modèle est réaliste, nous avons formalisé la validité d'un modèle de mobilité dans un contexte donné. Enfin, nous avons analysé deux ensembles de traces GPS provenant de mesures sur le terrain pour la définition d'un contexte de validité basé sur ces traces.Wireless networks have witnessed an explosive development in the past few decades, both for civil and military uses. The wide variety of requirements and application scenarios have provided an abundance of research challenges, some of which encountered for the first time in the context of computer network communications at such significant scale. One of the major reasons of the success of these networks is the possibility to remain mobile while still using some of the services provided by the network. As a consequence, mobility modeling has become a first class actor of wireless network related studies. In this thesis we have studied the various aspects and properties making a mobility model appropriate for wireless network research, including but not limited to analytical and simulation studies of WLAN, MANET, VANET, DTN and Cellular networks. We have introduced the LEMMA, a general framework which facilitates the creation, modification, validation and verification of mobility models. The architecture is based on three simple principles enforcing few restrictions on model components. We have formulated the foundations necessary for defining and studying analytical models by following the principles of this architecture. Additionally, we have proved essential mathematical properties of the framework and have demonstrated both empirically and formally that any mobility model can be represented with LEMMA. In order to provide a strict correspondence to the intuitive idea of model realism we have formalized the validity of a model in a given context. Finally, we analyzed two real-world GPS trace data sets with and defined a context of validity based on these traces