11 research outputs found
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 thĂšse prĂ©sente les fondations thĂ©oriques et pratiques d'un systĂšme pour l'analyse statique de langages manipulant des documents et donnĂ©es XML. Le systĂšme s'appuie sur une logique temporelle de point fixe avec programmes inverses, dĂ©rivĂ©e du mu-calcul modal, dans laquelle les modĂšles sont des arbres finis. Cette logique est suffisamment expressive pour prendre en compte les langages rĂ©guliers d'arbres ainsi que la navigation multidirectionnelle dans les arbres, tout en ayant une complexitĂ© simplement exponentielle. La principale application de ce travail est une nouvelle classe d'analyseurs statiques pour les langages de programmation utilisant des requĂȘtes XPath et des types rĂ©guliers d'arbres. De tels analyseurs permettent de s'assurer de propriĂ©tĂ©s importantes comme le typage correct des programmes ou leur optimisation, pour un traitement plus sĂ»r et plus efficace des donnĂ©es 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 âwatt balanceâ 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
DĂ©termination de lâaccĂ©lĂ©ration 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 â8. This work aims at determining g with an atomic gravimeter and a dedicated gravimetric site.Le projet « balance du watt » propose de relier la dĂ©finition du kilogramme Ă la constante de Planck. La pesĂ©e de la masse impliquĂ©e nĂ©cessite une dĂ©termination de l'accĂ©lĂ©ration de la pesanteur g avec une exactitude meilleure que 10^â8. Les travaux rĂ©sumĂ©s dans cet article visent Ă rĂ©aliser cette dĂ©termination Ă l'aide d'un gravimĂštre atomique et d'un site gravimĂ©trique dĂ©diĂ©