Inheritance hierarchies: Semantics and unification

Inheritance hierarchies are introduced as a means of representing taxonomicallyorganized data. The hierarchies are built up from so-called feature types that are ordered by subtyping and whose elements are records. Every feature type comes with a set of features prescribing fields of its record elements. So-called feature terms are available to denote subsets of feature types. Feature unification is introduced as an operation that decides whether two feature terms have a nonempty intersection and computes a feature term denoting the intersection.We model our inheritance hierarchies as algebraic specifications in ordersortedequational logic using initial algebra semantics. Our framework integrates feature types whose elements are obtained as records with constructor types whose elements are obtained by constructor application. Unification in these hierarchies combines record unification with order-sorted term unification and is presented as constraint solving. We specify a unitary unification algorithm by a set of simplification rules and prove its soundness and completeness with respect to the model-theoretic semantics

A Database Interface for Complex Objects

We describe a formal design for a logical query language using psi-terms as data structures to interact effectively and efficiently with a relational database. The structure of psi-terms provides an adequate representation for so-called complex objects. They generalize conventional terms used in logic programming: they are typed attributed structures, ordered thanks to a subtype ordering. Unification of psi-terms is an effective means for integrating multiple inheritance and partial information into a deduction process. We define a compact database representation for psi-terms, representing part of the subtyping relation in the database as well. We describe a retrieval algorithm based on an abstract interpretation of the psi-term unification process and prove its formal correctness. This algorithm is efficient in that it incrementally retrieves only additional facts that are actually needed by a query, and never retrieves the same fact twice

Evaluation des services et dis-services écosystémiques rendus par les cultures intermédiaires multi-services et par la biofumigation pour améliorer la productivité du tournesol

Le tournesol présente des atouts agro-écologiques (économe en intrants, tolérant à la sécheresse) et occupe une place importante parmi les cultures oléagineuses. La culture est semée après une interculture pendant laquelle le sol reste sans couverture, ce qui peut l’exposer à une lixiviation de nutriments. Aussi, deux bioagresseurs telluriques de la culture (Verticillium dahliae et Orobanche cumana) sont en expansion. L’interculture pourrait être valorisée par l’implantation de cultures intermédiaires multi-services (CIMS), telles que des Brassicacées pour leurs effets pièges à nitrates et leurs propriétés allélopathiques, qui permettent une production de molécules au potentiel biocide, notamment lors de son broyage et de son enfouissement (biofumigation). De plus, des Fabacées peuvent enrichir le sol en nitrates. Leur association pourrait induire une mutualisation de ces effets. L’objectif de la thèse était d’évaluer des services écosystémiques fournis par l’introduction de Brassicacées ou une Fabacée, seules ou associées, et de la biofumigation sur le tournesol. De potentiels dis-services sur des communautés microbiennes d’intérêt agronomique ont aussi été étudiés. Les CIMS choisies étaient la moutarde brune, le radis fourrager, la navette fourragère et la vesce du Bengale. Les expérimentations menées au laboratoire qui visaient à exposer V. dahliae et O. cumana à des broyats ont mis en évidence des régulations du développement du V. dahliae sur milieu de culture grâce aux Brassicacées et de la germination d’O. cumana (effet prédominant de la moutarde brune) et des effets plus variables des broyats sur le nombre de fixations ou d’émergences d’Orobanche. Au champ, la régulation de la Verticilliose est plus variable. Le radis fourrager semble être la CIMS la plus prometteuse pour lutter contre cette maladie, avec une réduction des dégâts ayant atteint 40% en 2016. Cependant, cette régulation pourrait dépendre de différents facteurs (météorologiques et techniques). Les effets des CIMS sur les quantités d’azote dans le sol et des rendements, en comparaison au sol nu, sont également variables en fonction des années et des CIMS. Une augmentation de l’azote (+50 kg.N.ha-1) a été observée en 2019, suite à de la vesce du Bengale. Une augmentation du rendement du tournesol a été observée (+0.7 t.ha-1) suite à la vesce du Bengale en 2020, mais des réductions (-0.5 à -0.6 t.ha-1) sont également à noter suite à un mélange. Aucun dis-service à l’égard de communautés microbiennes n’a été identifié durant ce travail de thèse. Les CIMS et la biofumigation, en particulier le radis fourrager ou la vesce du Bengale, auraient le potentiel de fournir des services écosystémiques, mais leur expression dépend des conditions météorologiques et de l’itinéraire cultural mis en place. Des travaux sont nécessaires afin de confirmer les effets observés, et pourraient s’appuyer sur une plus large diversité d’espèces et de variétés de radis, de vesces ainsi que de tournesols à évaluer. Des validations au sein de réseaux d’expérimentation chez des agriculteurs pourraient aussi être envisagées

Rare event sampling with stochastic growth algorithms

We discuss uniform sampling algorithms that are based on stochastic growth methods, using sampling of extreme configurations of polymers in simple lattice models as a motivation. We shall show how a series of clever enhancements to a fifty-odd year old algorithm, the Rosenbluth method, led to a cutting-edge algorithm capable of uniform sampling of equilibrium statistical mechanical systems of polymers in situations where competing algorithms failed to perform well. Examples range from collapsed homo-polymers near sticky surfaces to models of protein folding.Comment: First International Conference on Numerical Physic

Study of mechanical behavior by fatigue of a cracked plate repaired by different composite patches

This research is based on the study of the fatigue behavior of an aluminum alloy plate with a central crack. The plate is subjected to a tensile loading on its lower and upper parts. Several parameters were highlighted, such as the loading effect with a load ratio R = 0. The effects of the load ratio on both the repaired and not repaired plates, by two composite patches, which are boron/epoxy and graphite/epoxy, were investigated, as well as the effect of the plate material on plate life, comparing different material

Comparative study of the repair of cracked plates with two different composite patches

The purpose of this study is to analyze the behavior of a crack with and without reinforcement by a composite patch of an aluminum plate in mode I using the finite element method. The repair patch is boron / epoxy and Carbon / epoxy, which are used with great success by many researchers For the distribution of the stresses according to the various loadings, we can conclude that the effect of repair by patch in composite is very distinct, considering the intensities of stresses which decrease for each repair corresponding to the plate not repaired, therefore, the patch in composite dampens the stress field induced at the crack tip and causes a reduction in stresses. The repair with the Bore / epoxy composite patch is more effective than the Carbon/Epoxy patch, this is due to the mechanical properties and the various characteristics specific to boron/Epoxy which gives very significant and very effective results for the repai

Parallel backtracking with answer memoing for independent and-parallelism

Goal-level Independent and-parallelism (IAP) is exploited by scheduling for simultaneous execution two or more goals which will not interfere with each other at run time. This can be done safely even if such goals can produce múltiple answers. The most successful IAP implementations to date have used recomputation of answers and sequentially ordered backtracking. While in principie simplifying the implementation, recomputation can be very inefficient if the granularity of the parallel goals is large enough and they produce several answers, while sequentially ordered backtracking limits parallelism. And, despite the expected simplification, the implementation of the classic schemes has proved to involve complex engineering, with the consequent difficulty for system maintenance and extensión, while still frequently running into the well-known trapped goal and garbage slot problems. This work presents an alternative parallel backtracking model for IAP and its implementation. The model features parallel out-of-order (i.e., non-chronological) backtracking and relies on answer memoization to reuse and combine answers. We show that this approach can bring significant performance advantages. Also, it can bring some simplification to the important engineering task involved in implementing the backtracking mechanism of previous approaches

Numerical simulation of a crack emanating from a micro-cavity in the orthopedic cement by technical sub modeling of total hip prosthesis

PMMA has important micro structural heterogeneities such as cavities, and its elastic behavior is greatly affected by the presence of defects that may imply its weakening and cause failure. In areas of high concentrations of stress and due to the presence of cavities, micro cracks appear after crushing cavities due to patient movements, and grow and weld to each other until they form a macro     fissure that propagates until the total removal of the prosthesis.. In this study, the existence of a crack emanating from  a cavity with a diameter of 0.7 mm was assumed; our assessment takes into account two parameters, the position of the crack in the cement and we calculated the stress intensity factor (SIF) in the proximal part of orthopedic cement

Lightweight compilation of (C)LP to JavaScript

We present and evaluate a compiler from Prolog (and extensions) to JavaScript which makes it possible to use (constraint) logic programming to develop the client side of web applications while being compliant with current industry standards. Targeting JavaScript makes (C)LP programs executable in virtually every modern computing device with no additional software requirements from the point of view of the user. In turn, the use of a very high-level language facilitates the development of high-quality, complex software. The compiler is a back end of the Ciao system and supports most of its features, including its module system and its rich language extension mechanism based on packages. We present an overview of the compilation process and a detailed description of the run-time system, including the support for modular compilation into separate JavaScript code. We demonstrate the maturity of the compiler by testing it with complex code such as a CLP(FD) library written in Prolog with attributed variables. Finally, we validate our proposal by measuring the performance of some LP and CLP(FD) benchmarks running on top of major JavaScript engines