Topology of communities for the collaborative recommendations to groups

International audienceMore and more systems allow user personalization and provide item recommendations, intended to fit individual user interests. In a traditional VoD system, for example, the recommendations are oriented towards a single user even though he is not watching the video alone. Hence, there is a need to have recommendations for a set of users, a group. Collaborative filtering techniques are traditionally used to make a recommendation for a single user. Usage traces or user ratings are used to deduce their profile and to select an appropriate recommendation that way. Performing recommendation for groups is considerably more difficult because the retrieval of a group's traces of usage or ratings is complicated. As the individual profile for each member of the group is usually available, the recommendation for a group can be based on these individual profiles. This paper explores this approach and is the first step of the construction of a software toolkit for computing recommendations in function of the group composition and the chosen strategies

Analysis of strategies for building group profiles

International audienceToday most of existing personalization systems (e.g. content recommenders, or targeted ad) focus on individual users and ignore the social situation in which the services are consumed. However, many human activities are social and involve several individuals whose tastes and expectations must be taken into account by the service providers. When a group profile is not available, different profile aggregation strategies can be applied to recommend adequate content and services to a group of users based on their individual profiles. In this paper, we consider an approach intended to determine the factors that influence the choice of an aggregation strategy. We present a preliminary evaluation made on a real large-scale dataset of TV viewings, showing how group interests can be predicted by combining individual user profiles through an appropriate strategy. The conducted experiments compare the group profiles obtained by aggregating individual user profiles according to various strategies to the "reference" group profile obtained by directly analyzing group consumptions

AGATH : Utilisation de plantes de service et de kaolin pour gérer les populations de pucerons et de thrips en cultures légumières.

Dans un contexte règlementaire en pleine évolution (diminution du nombre de spécialités phytosanitaires disponibles), la maitrise du puceron Aphis gossypii dans les cultures de melon et de Thrips tabaci dans les cultures de poireau à l’aide de solutions phytosanitaires est de plus en plus difficile, et la recherche de méthodes de lutte alternatives et/ou complémentaires est nécessaire. Dans cette optique, des stratégies de protection basée sur l’utilisation de plantes de service (plantesressources, plantes-banque, plantes répulsives, plantes-écran et plantes-piège) ou bien sur l’utilisation de produits alternatifs (kaolin) ont été mises au point et évaluées dans le cadre du projet Casdar AGATH, porté par le CTIFL de 2013 à 2015 et labellisé par le GIS PICleg. Les résultats obtenus montrent que la mise en place de plantes-ressources et de plantes-banque autour des parcelles pourrait être efficace pour gérer A. gossypii en cultures de melon mais pas pour gérer T. tabaci en cultures de poireau, tandis que le phénomène inverse est observé pour ce qui concerne l’utilisation de plantes-répulsives et de kaolin. Enfin, certaines stratégies telles que l’utilisation de plantes-écran et/ou de plantes-piège n’ont pas montré d’intérêt dans le contexte expérimental des travaux menés.In a constant changing context (reduction in the number of pesticides available) the control of Aphis gossypii populations in melon crops and of Thrips tabaci populations in leek crops using pesticides is increasingly difficult. Then, the search for alternative and/or complementary solutions is required. With this in mind, new strategies of protection based on the use of service plants (resource-plants, bankerplants, repellent-plants, screen and/or trap plants) or on the use of natural products such as kaolin have been developed and evaluated in the framework of the AGATH project, managed by the French Institute for Fruits and Vegetables (CTIFL) from 2013 to 2015, supported by the French Ministry of Agriculture and Food, and labelled by the PICleg consortium. The results showed that the setting up of resourceplants and/or banker-plants all around the fields could be effective in controlling A. gossypii in melon crops but not in controlling T. tabaci in leek crops, while it is the opposite as far as the use of repellentplants or kaolin are concerned. Finally, some strategies such as the use of screen and/or trap plants did not show any interest in the experimental context of the work carried out