Esta es la versión de autor del artículo publicado en: This is an author produced version of a paper published in: In this paper we analyze viable solutions to the new user problem in collaborative filtering that are based on the exploitation of user personality information: (a) personality-based collaborative filtering, which directly improves the recommendation prediction model by incorporating user personality information; (b) personality-based active learning, which utilizes personality information for identifying additional useful preference data in the target recommendation domain to be elicited from the user; and (c) personality-based cross-domain recommendation, which exploits personality information to better use user preference data from auxiliary domains which can be used to compensate the lack of user preference data in the target domain. We benchmark the effectiveness of these methods on large datasets that span several domains, namely movies, music and books. Our results show that personality-aware methods achieve performance improvements that range from 6% to 94% for users completely new to the system, while increasing the novelty of the recommended items by 3% to 40% with respect to the non-personalized popularity baseline. We also discuss the limitations of our approach and the situations in which the proposed methods can be better applied, hence providing guidelines for researchers and practitioners in the field.

Abstract. Recommender systems (RSs) suffer from the cold-start or new user/item problem, i.e., the impossibility to provide a new user with accurate recommendations or to recommend new items. Active learning (AL) addresses this problem by actively selecting items to be presented to the user in order to acquire her ratings and hence improve the output of the RS. In this paper, we propose a novel AL approach that exploits the user's personality -using the Five Factor Model (FFM) -in order to identify the items that the user is requested to rate. We have evaluated our approach in a user study by integrating it into a mobile, contextaware RS that provides users with recommendations for places of interest (POIs). We show that the proposed AL approach significantly increases the number of ratings acquired from the user and the recommendation accuracy.

The increasing amount of online music content has opened opportunities for implementing new effective information access services-commonly known as music recommender systems-that support music navigation, discovery, sharing, and formation of user communities. In recent years, a new research area of contextual music recommendation and retrieval has emerged. Context-aware music recommender systems are capable of suggesting music items taking into consideration contextual conditions, such as the user's mood or location, that may influence the user's preferences at a particular moment. In this work, we consider a particular kind of context-aware recommendation taskselecting music content that fits a place of interest (POI). To address this problem we have used emotional tags assigned to both music tracks and POIs, and we have considered a set of similarity metrics for tagged resources to establish a match between music tracks and POIs. Following an initial webbased evaluation of the core matching technique, we have developed a mobile application that suggests an itinerary and plays recommended music for each visited POI, and evaluated it in a live user study. The results of the study show that users judge the recommended music as suited for the POIs, and that the music is rated higher when it is played in this usage scenario.

Abstract. Recommender systems suffer from the new user problem, i.e., the difficulty to make accurate predictions for users that have rated only few items. Moreover, they usually compute recommendations for items just in one domain, such as movies, music, or books. In this paper we deal with such a cold-start situation exploiting cross-domain recommendation techniques, i.e., we suggest items to a user in one target domain by using ratings of other users in a, completely disjoint, auxiliary domain. We present three rating prediction models that make use of information about how users tag items in an auxiliary domain, and how these tags correlate with the ratings to improve the rating prediction task in a different target domain. We show that the proposed techniques can effectively deal with the considered cold-start situation, given that the tags used in the two domains overlap.

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