Finding low-weight polynomial multiples using discrete logarithm

Finding low-weight multiples of a binary polynomial is a difficult problem arising in the context of stream ciphers cryptanalysis. The classical algorithm to solve this problem is based on a time memory trade-off. We will present an improvement to this approach using discrete logarithm rather than a direct representation of the involved polynomials. This gives an algorithm which improves the theoretical complexity, and is also very flexible in practice

Bandwidth selection for kernel estimation in mixed multi-dimensional spaces

Kernel estimation techniques, such as mean shift, suffer from one major drawback: the kernel bandwidth selection. The bandwidth can be fixed for all the data set or can vary at each points. Automatic bandwidth selection becomes a real challenge in case of multidimensional heterogeneous features. This paper presents a solution to this problem. It is an extension of \cite{Comaniciu03a} which was based on the fundamental property of normal distributions regarding the bias of the normalized density gradient. The selection is done iteratively for each type of features, by looking for the stability of local bandwidth estimates across a predefined range of bandwidths. A pseudo balloon mean shift filtering and partitioning are introduced. The validity of the method is demonstrated in the context of color image segmentation based on a 5-dimensional space

Projet interordres sur les applications pédagogiques de la conception universelle de l’apprentissage : rapport final

Ont collaboré: Dominique Alarie, Marie Blain, Yves Carignan, Nathalie Giguère, Thomas Henderson, Carole Lavallée, Catherine Loiselle, Dolores Otero, Hélène Trifiro, Stéphanie Tremblay, Paul Turcotte, Florence Lebeau, Brigitte Auclair, Véronique Besançon, Jean-René Corbeil, Antoine Coulombe, Johanne Morin, Cédric Lamathe, Florence Lebeau, Paul Turcotte, Steve Vezeau

Interaction Grammars

Interaction Grammar (IG) is a grammatical formalism based on the notion of polarity. Polarities express the resource sensitivity of natural languages by modelling the distinction between saturated and unsaturated syntactic structures. Syntactic composition is represented as a chemical reaction guided by the saturation of polarities. It is expressed in a model-theoretic framework where grammars are constraint systems using the notion of tree description and parsing appears as a process of building tree description models satisfying criteria of saturation and minimality

Improved Incremental Randomized Delaunay Triangulation

We propose a new data structure to compute the Delaunay triangulation of a set of points in the plane. It combines good worst case complexity, fast behavior on real data, and small memory occupation. The location structure is organized into several levels. The lowest level just consists of the triangulation, then each level contains the triangulation of a small sample of the levels below. Point location is done by marching in a triangulation to determine the nearest neighbor of the query at that level, then the march restarts from that neighbor at the level below. Using a small sample (3%) allows a small memory occupation; the march and the use of the nearest neighbor to change levels quickly locate the query.Comment: 19 pages, 7 figures Proc. 14th Annu. ACM Sympos. Comput. Geom., 106--115, 199

Les NTIC et les étudiants ayant des handicaps au postsecondaire recherches empiriques à valeur pragmatique : repères pour l'adaptation de l'éducation

Également disponible en version papierTitre de l'écran-titre (visionné le 4 mars. 2010)Comprend des références bibliographiques

Coconut Phytophthora. Workshop proceedings, 26-30 October 1992, Manado, Indonesia

Ce séminaire sur le Phythophthora du cocotier avait pour but de réunir tous les acteurs d'un projet démarré en 1990 et de faire le point sur les études réalisées pour la connaissance et la lutte contre ce champignon. Ce projet a donné une grande priorité aux échanges d'informations et aux complémentarités entre les équipes de recherche européennes et tropicale

Characterizing and approximating eigenvalue sets of symmetric interval matrices

We consider the eigenvalue problem for the case where the input matrix is symmetric and its entries perturb in some given intervals. We present a characterization of some of the exact boundary points, which allows us to introduce an inner approximation algorithm, that in many case estimates exact bounds. To our knowledge, this is the first algorithm that is able to guaran- tee exactness. We illustrate our approach by several examples and numerical experiments