1,721,056 research outputs found
Teoría de prueba con etiquetas para lógicas modales intuicionistas
Get PDFLos sistemas de prueba etiquetados han sido propuestos por Gabbay como un marco unificador a través de la teoría de prueba con el fin de proporcionar sistemas de prueba para una amplia gama de lógicas. Para las lógicas modales, un ejemplo de ello son, por ejemplo, los sistemas de deducción natural etiquetados y sistemas de secuentes etiquetados, tales como los introducidos por Simpson y Negri. Estos formalismos hacen uso explícito no sólo de las etiquetas, sino también de los átomos relacionales que se refieren a la relación de accesibilidad de un modelo de Kripke.
El objetivo principal de este trabajo final de Licenciatura, es poder proponer un sistema de prueba etiquetado para una Lógica Modal Intuicionista, que represente tanto la relación de accesibilidad (para la lógica modal) como la relación de preorden (para la lógica intuicionista), utilizando todo el poder de la semántica bi-relacional para las lógicas modales intuicionistas
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Optimisation du code source pour les systèmes critiques de sécurité
No full textUn système informatique est dit critique de sécurité lorsqu'il peut causer de graves dommages matériels, environnementaux ou humains.Ce type de système est nécessairement complexe, car les interactions entre logiciel, matériel et environnement,nécessitent l'implémentation de mesures de sécurité aussi bien au niveau logiciel que matérielpendant leur conception, leur développement, leur compilation et leur exécution. Ces mesures de sécurité qui varient un système à un autreconduisent très souvent à des dégradations de performances, en particulier l'augmentation du temps d'exécution.Ce travail de recherche se situe dans le contexte du système CBTC (Communication-Based Train Control) deSiemens Mobility France, un système de contrôle de train certifié EN-50128 et SIL-4 (le plus haut niveau de sûreté) dans le développement de nombreux systèmes de pilote automatiqueà travers le monde, en particulier sur les lignes 1, 4 et 14 du métro parisien.Dans ce contexte, le but de cette thèse est de trouver des solutions pour réduire le temps d'exécution de ces systèmes tout en conservantles garanties de sécurité déjà acquises.La réponse apportée par cette thèse est une optimisation formellement vérifiée du code source. Une première contribution est un compilateur VCP Ada (un sous-ensemble d'Ada)vers VCP Ada, qui optimise le code source tout en préservant la sémantique des programmes. Ce compilateur a été implémenté avecl'assistant de preuve Coq et fourni des preuves en Coq qui garantissent l'équivalence entre le programme original et le programme optimisé.Ce compilateur tient aussi compte des complexités liées aux mesures de sécurité matérielle qui sont potentiellement incompatibles avec l'utilisation des compilateursformellement vérifiés existants. Par ailleurs, le choix de l'application des optimisations sur le code source présente des avantages méthodologiques parrapport aux optimisations utilisant de nombreux langages intermédiaires, car ils permettent de simplifier et de réduire l'effort de preuve nécessaire.Une deuxième contribution concerne la vérification formelle des analyseurs lexicaux des compilateurs, qui n'a jusqu'à présent, pas reçu beaucoup l'attention de la part deschercheurs, créant donc un maillon faible dans la chaîne de compilation. Nous avons développé CoqLex, le premier générateur d'analyseur lexical formellement vérifié en Coq, basé sur unemodification d'une implémentation existante en Coq des expressions régulières via les dérivés de Brzozowski.La théorie et les outils développés ont été utilisés pour optimiser les programmes VCP Ada des systèmes CBTC, composés de milliers de fichiers sources, avec desrésultats prometteurs.A computer system is safety-critical when it can cause serious damages to property, the environment, human life, or to the societyas a whole. Real-world safety-critical systems are also necessarily complex, because, in order to take into account the interactionsbetween software, hardware, the physical environment, and sometimes their distributed nature (systems of systems), they need to implementa variety of safety measures, in software, in hardware, in the system design, at development time, at compile time, and at run-time. Those safety measureswhich vary from one safety-critical system to another very often lead to decrease of performance, for increase of execution time of software.This research work is situated in the context of one such system, the communication-based train control (CBTC) system ofSiemens Mobility France which operates a number of driverless subway systems around the World, including the Paris lines 1, 4, and 14. That system is certified according to the industrial norm EN-50128and up to the highest Safety Integrity Level 4, required for safety-critical systems with potentially catastrophic consequences.In this context, the thesis looks for an answer to the question of how to automatically optimize execution time performance of such systems withoutloosing the previously obtained safety guarantees.The answer provided by this thesis is provably correct optimization of source code. A first contribution is a source-to-source compilerfor VCP Ada (a subset of Ada) programs, that optimizes source code while preserving the formal semantics of the programs. The compiler has been provencorrect in the Coq proof assistant and guarantees the equivalence of execution between the original and the optimized program. Thecompiler copes with the complexities of the platform, due to hardware safety measures, which is important, since real-worldsafety-critical system are often susceptible to have such measures, potentially conflicting with existing formally proven optimizingcompilers. Moreover, choosing the approach of a source-to-source compilation shows to have methodological advantages over an approachto proven optimizations having a number of intermediate languages, allowing to simplify and diminish the needed proof effort.A second contribution is to the problem of provably correct lexical analysis of compilers, which has previously not received a lot ofresearch attention, a weak link in any compilation chain using a proven or qualified compiler. We develop CoqLex, the firstCoq-formalized lexer generator, based on a modification of an existing Coq implementation of regular expression matching viaBrzozowski derivatives.The developed theory and tools have been applied to optimize real-world VCP Ada programs of CBTC systems, consisting of thousandsof source files, with promising results
Systèmes de preuve inhabituels pour la logique modale avec applications aux problèmes de décision
No full textCette thèse explore rigoureusement les logiques modales, les analysant du point de vue de la théorie de la preuve. Dans le contexte intuitionniste des logiques modales, nous présentons un système de séquents entièrement étiqueté, dans lequel non pas un, mais deux symboles de relation apparaissent dans les séquents: l'un pour la relation d'accessibilité associée à la sémantique de Kripke des logiques modales normales, et l'autre pour la relation de préordre associée à la sémantique de Kripke de la logique intuitionniste. Nous étendons ce système pour englober les quinze logiques modales intuitionnistes distinctes du cube S5. Les avantages de ce système, tels que toutes ses règles d'inférence sont inversibles et qu'il existe une correspondance directe entre les séquents et les modèles, nous permettent d'explorer les problèmes de décision pour différentes variantes des logiques modales intuitionnistes, telles que IK, IT, IB, ITB, IK5. En particulier, nous effectuons une recherche de preuves dans notre système de séquents entièrement étiqueté et nous proposons une procédure de décision pour prouver la décidabilité des logiques mentionnées. Nous étendons ensuite cet algorithme de recherche pour résoudre un problème ouvert depuis près de trente ans depuis qu'il a été posé dans la thèse de doctorat de Simpson en 1994: nous démontrons la décidabilité de la logique modale intuitionniste S4. Notre algorithme de recherche produit soit une preuve, soit un contre-modèle fini, établissant ainsi la propriété de modèle fini pour l'intuitionniste S4, qui était un autre problème ouvert de longue date dans ce domaine. Dans le cadre classique des logiques modales, nous présentons un travail en cours dans le formalisme de l'inférence profonde en utilisant la méthodologie de la théorie de la preuve subatomique. Nous présentons un système de preuve subatomique pour le fragment linéaire des logiques modales classiques, montrant son "cut-elimination via splitting". Suite à cette preuve, nous démontrons l'admissibilité des règles ascendantes, qui sont les "cuts".This thesis rigorously explores modal logics, analyzing them from a proof theory perspective. In the intuitionistic setting of modal logics, we present a fully labelled sequent system such that there is not only one, but two relation symbols appearing in sequents: one for the accessibility relation associated with the Kripke semantics for normal modal logics and one for the preorder relation associated with the Kripke semantics for intuitionistic logic. We extend this system to capture the fifteen distinct intuitionistic modal logics of the S5-cube. The advantages of this system, such as all its inference rules are invertible and that there is a direct correspondence between sequents and models, allow us to explore decision problems for different variants of intuitionistic modal logics, such as IK, IT, IB, ITB, IK5. In particular, we perform proof search in our fully labelled sequent system and we give a decision procedure to prove decidability of the mentioned logics. We then extend this search algorithm to solve a problem that has been open for almost thirty years since it had been posed in Simpson’s PhD thesis in 1994: we demonstrate decidability of the intuitionistic modal logic S4. Our search algorithm outputs either a proof or a finite counter-model, thus, additionally establishing the finite model property for intuitionistic S4, which has been another long-standing open problem in the area. In the classical setting of modal logics, we present a work in progress in the formalism of deep inference using the methodology of subatomic proof theory. We present a subatomic proof system for the linear fragment of classical modal logics, showing its cut-elimination via splitting. As a result of this proof, we show the admissibility of the up-rules which are the cuts
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
