Symmetric Subresultants and Applications

Schur's transforms of a polynomial are used to count its roots in the unit disk. These are generalized them by introducing the sequence of symmetric sub-resultants of two polynomials. Although they do have a determinantal definition, we show that they satisfy a structure theorem which allows us to compute them with a type of Euclidean division. As a consequence, a fast algorithm based on a dichotomic process and FFT is designed. We prove also that these symmetric sub-resultants have a deep link with Toeplitz matrices. Finally, we propose a new algorithm of inversion for such matrices. It has the same cost as those already known, however it is fraction-free and consequently well adapted to computer algebra

A Visibility and Spatial Constraint-Based Approach for Geopositioning

Over the past decade, automated systems dedicated to geopositioning have been the object of considerable development. Despite the success of these systems for many applications, they cannot be directly applied to qualitative descriptions of space. The research presented in this paper introduces a visibility and constraintbased approach whose objective is to locate an observer from the verbal description of his/her surroundings. The geopositioning process is formally supported by a constraint-satisfaction algorithm. Preliminary experiments are applied to the description of environmental scenes

A semantic and language-based representation of an environmental scene

The modeling of a landscape environment is a cognitive activity that requires appropriate spatial representations. The research presented in this paper introduces a structural and semantic categorization of a landscape view based on panoramic photographs that act as a substitute of a given natural environment. Verbal descriptions of a landscape scene provide themodeling input of our approach. This structure-based model identifies the spatial, relational, and semantic constructs that emerge from these descriptions. Concepts in the environment are qualified according to a semantic classification, their proximity and direction to the observer, and the spatial relations that qualify them. The resulting model is represented in a way that constitutes a modeling support for the study of environmental scenes, and a contribution for further research oriented to the mapping of a verbal description onto a geographical information system-based representation

A Visibility and Spatial Constraint-Based Approach for Geopositioning

Over the past decade, automated systems dedicated to geopositioning have been the object of considerable development. Despite the success of these systems for many applications, they cannot be directly applied to qualitative descriptions of space. The research presented in this paper introduces a visibility and constraintbased approach whose objective is to locate an observer from the verbal description of his/her surroundings. The geopositioning process is formally supported by a constraint-satisfaction algorithm. Preliminary experiments are applied to the description of environmental scenes

Comprehension of Texts, Inferences and Functional Modularity

El presente artículo revisa el vínculo entre la modularidad de los procesos psicolingüísticos de base y la obligatoriedad y automaticidad de procesos inferenciales implicados en los procesos de comprensión del texto. Se recurre a la hipótesis modular de Fodor (1983), así como a investigaciones de la psicología de la comprensión del texto. Se señalan las diferencias entre procesos modulares y no-modulares, argumentando que la automaticidad y rapidez en el nivel de la comprensión textual no son suficientes para sostener el carácter obligatorio de dichos procesos, en un sentido modular. Asimismo, se revisan investigaciones que cuestionan la utilización de un criterio de curso temporal de la inferencia como índice para establecer la obligatoriedad de la misma. Finalmente, se reflexiona sobre la relación entre el procesamiento del texto y los procesos psicolingüísticos de base, y sobre cómo ello impacta en la producción de estrategias educativas orientadas a la comprensión del lenguaje.This article reviews the link between the modularity of basic psycholinguistic processes and mandatory, automatic inferential processes, involved in text comprehension. The review is based on Fodor´s modular hypothesis (1983), as well as on research works in the field of psychology,related to text comprehension. Differences between modular and non-modular processes are highlighted, arguing that automaticity and speed in text comprehension are not sufficient to conceive these processes as mandatory, in a modular fashion. Empirical results that question the use of temporal course as criterion to ascertain the mandatory nature of an inference are reviewed. Finally, some conclusions are drawn on the relationship between text processing and basic psycholinguistic processes, as well as how it impacts on the development of educational strategies aimed at language comprehension.Fil: Saux, Gaston Ignacio. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

La femme, le chien et le clerc

This article explores the symbolical nexus between woman and animal in the Middle English fabliau of Dame Sirith and the Weeping Bitch. It offers a new interpretation of the character of Margery in the light of the Liber vaccae, a pseudo-scientific treatise that circulated widely in university circles from the early thirteenth century onwards. This work attests to the reality of the belief, even among the educated, of the possibility of turning a human being into an animal. The young wife’s credulity is not just an idiosyncratic weakness, therefore, as has generally been assumed by previous critics. Caxton’s version of the tale shows his uneasiness with this aspect of the fabliau, explaining his setting of the story in a distant, pagan land rather than Christian England, and his substituting a cat (with its attendant demonic association) to the dog of the earlier narrative. Cette étude explore le réseau symbolique entre femme et animal dans le fabliau moyen-anglais Dame Sirith and the Weeping Bitch, et offre une réinterprétation du personnage de Margery à la lumière du Liber vaccae. Cet ouvrage (pseudo-)scientifique bien connu dans les milieux universitaires dès le début du XIIIe siècle atteste une croyance en la possibilité de transformer un être humain en animal: la crédulité de la jeune femme relèverait ainsi d’un trait de société, tout autant que d’une faiblesse personnelle. Les changements apportés par Caxton à sa version du fabliau – en particulier, sa substitution d’une chienne par une chatte dans son récit de la ruse de l’entremetteuse, et un retour au context païen de l’histoire telle que la relate Petrus Alfonsi – sont révélateurs d’un désir de distanciation par rapport à une thématique plus dérangeante que ne l’aurait soupçonné le lecteur du XXIe siècle