Exploiting past users’ interests and predictions in an active learning method for dealing with cold start in recommender systems

This paper focuses on the new users cold-start issue in the context of recommender systems. New users who do not receive pertinent recommendations may abandon the system. In order to cope with this issue, we use active learning techniques. These methods engage the new users to interact with the system by presenting them with a questionnaire that aims to understand their preferences to the related items. In this paper, we propose an active learning technique that exploits past users’ interests and past users’ predictions in order to identify the best questions to ask. Our technique achieves a better performance in terms of precision (RMSE), which leads to learn the users’ preferences in less questions. The experimentations were carried out in a small and public dataset to prove the applicability for handling cold start issues

Enhancing new user cold-start based on decision trees active learning by using past warm-users predictions

The cold-start is the situation in which the recommender system has no or not enough information about the (new) users/items, i.e. their ratings/feedback; hence, the recommendations are not accurate. Active learning techniques for recommender systems propose to interact with new users by asking them to rate sequentially a few items while the system tries to detect her preferences. This bootstraps recommender systems and alleviate the new user cold-start. Compared to current state of the art, the presented approach takes into account the users' ratings predictions in addition to the available users' ratings. The experimentation shows that our approach achieves better performance in terms of precision and limits the number of questions asked to the users

An item/user representation for recommender systems based on bloom filters

This paper focuses on the items/users representation in the domain of recommender systems. These systems compute similarities between items (and/or users) to recommend new items to users based on their previous preferences. It is often useful to consider the characteristics (a.k.a features or attributes) of the items and/or users. This represents items/users by vectors that can be very large, sparse and space-consuming. In this paper, we propose a new accurate method for representing items/users with low size data structures that relies on two concepts: (1) item/user representation is based on bloom filter vectors, and (2) the usage of these filters to compute bitwise AND similarities and bitwise XNOR similarities. This work is motivated by three ideas: (1) detailed vector representations are large and sparse, (2) comparing more features of items/users may achieve better accuracy for items similarities, and (3) similarities are not only in common existing aspects, but also in common missing aspects. We have experimented this approach on the publicly available MovieLens dataset. The results show a good performance in comparison with existing approaches such as standard vector representation and Singular Value Decomposition (SVD)

Aphtose buccale récidivante, et si c’était une maladie coeliaque

L’aphtose buccale récidivante est une maladie le plus souvent bénigne mais parfois invalidante qui évolue de façon chronique et récidivante. Ellepeut être isolée ou associé à d’autre pathologie, d’où l’intérêt de la recherche d’une maladie sous jacente. Nous rapportons le cas d’une aphtosebuccale récidivante révélant une maladie coeliaque chez une patiente âgée de 45 ans.Key words: Aphtose buccale, maladie coeliaque, récidiv

Zona chez le nourrisson: à propos d’un cas

Le zona est dû à la réactivation du virus varicelle-zona, celui-ci gagne les ganglions sensitif à partir d’un foyer cutané ou muqueux lors de la primo infection. La survenue de zona chez le nourrisson est une situation rare, celle-ci se caractérise par la prédominance des signes fonctionnelles à type de fièvre et de céphalée est l’absence de douleur post zostérienne. Le diagnostic est clinique et doit être évoqué devant des lésions vésiculeuses groupés en bouquet et dont la disposition suit un métamère. Les complications chez le nourrisson sont rares. Le traitement fait appel aux antiviraux