2020


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Lundi 12 Octobre
Heure: 12:30 - 14:00
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Person-Independent Multimodal Emotion Detection for Children with High-Functioning Autism
Description: Annanda Sousa The use of affect-sensitive interfaces carries the promise of enhancing human-computer interaction by delivering a system capable of identifying a user's emotions and adapt its content accordingly. Today's technology shows great potential to support children with autism, for example by using computer systems to improve their social skills. Generally, however, this technology does not encompass the potential of affect-sensitive interfaces. This is mainly due to Emotion Detection (ED) models built for the general population usually not performing well when applied to children with autism, who express emotions differently. The aim of this project is therefore to build a person-independent Multimodal Emotion Detection system tailored for children with high-functioning autism for the ultimate goal of applying it to design affect-sensitive interfaces dedicated to children with autism. This is a work in progress and the project expects to build upon the current body of knowledge on methods to apply ED systems to this specific subset of the general population. We expect to apply the overall theoretical and practical design perspectives that arise from this research investigation (e.g. analysis of modalities and features extraction, behavioural cues based features, fusion layers and classifier techniques) to propose a guiding framework for future studies.
Jeudi 5 Novembre
Heure: 10:30 - 11:30
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: An exact algorithm for robust influence maximization
Description: Roberto Wolfler Calvo We propose a Branch-and-Cut algorithm for the robust influence maximization problem. The influence maximization problem aims to identify, in a social network, a set of given cardinality comprising actors that are able to influence the maximum number of other actors. We assume that the social network is given in the form of a graph with node thresholds to indicate the resistance of an actor to influence, and arc weights to represent the strength of the influence between two actors. In the robust version of the problem that we study, the node thresholds are affected by uncertainty and we optimize over a worst-case scenario within a given robustness budget. Numerical experiments show that we are able to solve to optimality instances of size comparable to other exact approaches in the literature for the non-robust problem, but in addition to this we can also tackle the robust version with similar performance.
Jeudi 19 Novembre
Heure: 10:30 - 11:30
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: A Tight Approximation Algorithm for the Cluster Vertex Deletion Problem
Description: Samuel Fiorini We give the first 2-approximation algorithm for the cluster vertex deletion problem. This is tight, since approximating the problem within any constant factor smaller than 2 is UGC-hard. Our algorithm combines the previous approaches, based on the local ratio technique and the management of true twins, with a novel construction of a 'good' cost function on the vertices at distance at most 2 from any vertex of the input graph.
As an additional contribution, we also study cluster vertex deletion from the polyhedral perspective, where we prove almost matching upper and lower bounds on how well linear programming relaxations can approximate the problem.
Jeudi 26 Novembre
Heure: 10:30 - 12:00
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Émergence de nouveaux problèmes combinatoires pour les systèmes de production dans le contexte Industrie 4.0
Description: Paolo Gianessi Du fait des nouveaux paradigmes de production imposés par l'Industrie 4.0 et de l'attention grandissante portée par l'opinion publique à l'égard des questions environnementales, les systèmes de production doivent relever le double défi de répondre à une demande de plus en plus variable mais aussi faire preuve d'une efficacité énergétique accrue. De nouveaux problèmes combinatoires ont ainsi commencé à paraître dans la littérature de l'Optimisation des systèmes de production à coté des problèmes plus traditionnels. Nous en présentons ici trois, que nous avons étudiés au cours de ces deux dernières années, et qui touchent à la planification stratégique ou tactique/opérationnelle: un problème d'ordonnancement de type job-shop avec prise en compte de l'énergie; un problème d'équilibrage de ligne avec minimisation du pic de puissance; et un problème bi-niveau d'équilibrage de ligne d'un RMS (système de production reconfigurable) visant à minimiser le coût de la consommation énergétique vis-à-vis d'un plan tarifaire donné. Ces problèmes ont pour l'instant été abordés par de premières approches simples (PLNE, méta-heuristiques par décomposition et/où recherche locale) afin d'en démontrer l'intérêt pratique auprès de la communauté industrielle; il paraît tout de même évident qu'ils offrent des développements potentiels à investiguer aussi d'un point de vue plus proprement algorithmique et combinatoire, et par conséquent s'affichent comme de nouveaux éléments d'intérêt certain de la frontière entre applications réelles et recherche fondamentale.
Jeudi 3 Décembre
Heure: 10:30 - 11:30
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Geometric Set Cover via Randomized LP Rounding
Description: Mustafa Nabil Geometric set-cover/hitting-set problems arise naturally in several basic settings, and therefore the problem of computing small set covers (and hitting sets) has been studied extensively. A common first step in solving such optimization problems is to formulate and solve the corresponding covering/packing LP to get a fractional solution. Then the task reduces to constructing an integer solution from this fractional solution. In this talk, I will present a new simple iterative randomized rounding scheme that gives optimal approximation bounds, within constant factors, for many well-studied geometric systems.
Jeudi 17 Décembre
Heure: 10:30 - 11:30
Lieu: Salle B107, bâtiment B, Université de Villetaneuse
Résumé: Combinatorial Optimization problems in telecommunication networksitre bientôt disponible
Description: Sébastien Martin The telecommunication network area provides lot of interesting optimization problems. Furthermore, the arrival of 5G technology modifies the traditional combinatorial optimization problems by adding some specificities. We quickly present some case studies done by the "network optimization" team from "Datacom" department. For instance, we present the "network slicing technology" ensuring isolation in resource sharing among users. We also describe the "Deterministic Networking" to guarantee bounded jitter and latency constraints. Finally, we show how to consider network calculus in optimization problems to ensure latency guarantees.
We finish by the presentation of future telecommunication network topics from an optimization point of view.

Joint work with Nicolas Huin, Jérémie Leguay, Youcef Magnouche, Paolo Medagliani