A Tree Logic with Graded Paths and Nominals

Regular tree grammars and regular path expressions constitute core constructs widely used in programming languages and type systems. Nevertheless, there has been little research so far on reasoning frameworks for path expressions where node cardinality constraints occur along a path in a tree. We present a logic capable of expressing deep counting along paths which may include arbitrary recursive forward and backward navigation. The counting extensions can be seen as a generalization of graded modalities that count immediate successor nodes. While the combination of graded modalities, nominals, and inverse modalities yields undecidable logics over graphs, we show that these features can be combined in a tree logic decidable in exponential time

Efficient Iterative Programs with Distributed Data Collections

Big data programming frameworks have become increasingly important for the development of applications for which performance and scalability are critical. In those complex frameworks, optimizing code by hand is hard and time-consuming, making automated optimization particularly necessary. In order to automate optimization, a prerequisite is to find suitable abstractions to represent programs; for instance, algebras based on monads or monoids to represent distributed data collections. Currently, however, such algebras do not represent recursive programs in a way which allows for analyzing or rewriting them. In this paper, we extend a monoid algebra with a fixpoint operator for representing recursion as a first class citizen and show how it enables new optimizations. Experiments with the Spark platform illustrate performance gains brought by these systematic optimizations.Comment: 36 page

Logiques pour XML

Cette thèse présente les fondations théoriques et pratiques d'un système pour l'analyse statique de langages manipulant des documents et données XML. Le système s'appuie sur une logique temporelle de point fixe avec programmes inverses, dérivée du mu-calcul modal, dans laquelle les modèles sont des arbres finis. Cette logique est suffisamment expressive pour prendre en compte les langages réguliers d'arbres ainsi que la navigation multidirectionnelle dans les arbres, tout en ayant une complexité simplement exponentielle. La principale application de ce travail est une nouvelle classe d'analyseurs statiques pour les langages de programmation utilisant des requêtes XPath et des types réguliers d'arbres. De tels analyseurs permettent de s'assurer de propriétés importantes comme le typage correct des programmes ou leur optimisation, pour un traitement plus sûr et plus efficace des données XML.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Efficient static analysis of XML paths and types

We present an algorithm to solve XPath decision problems under regular tree type constraints and show its use to statically type-check XPath queries. To this end, we prove the decidability of a logic with converse for finite ordered trees whose time complexity is a simple exponential of the size of a formula. The logic corresponds to the alternation free modal mu-calculus without greatest fixpoint, restricted to finite trees, and where formulas are cycle-free

Free fall acceleration determination for the LNE watt balance

The “watt balance” project aims at linking the kilogram definition to the Planck constant. The weighing of the mass involved requires a determination of the acceleration g with an uncertainty better than 10-8. This work aims at determining g with an atomic gravimeter and a dedicated gravimetric site

Détermination de l’accélération de la pesanteur pour la balance du watt du LNE

International audienceThe "watt balance" project aims at linking the kilogram definition to the Planck constant. The weighing of the mass involved requires a determination of the acceleration g with an uncertainty better than 10 −8. This work aims at determining g with an atomic gravimeter and a dedicated gravimetric site.Le projet « balance du watt » propose de relier la définition du kilogramme à la constante de Planck. La pesée de la masse impliquée nécessite une détermination de l'accélération de la pesanteur g avec une exactitude meilleure que 10^−8. Les travaux résumés dans cet article visent à réaliser cette détermination à l'aide d'un gravimètre atomique et d'un site gravimétrique dédié