In current Android architecture, users have to decide whether an app is safe to use or not. Expert users can make savvy decisions to avoid unnecessary private data breach. However, the majority of regular users are not technically capable or do not care to consider privacy implications to make safe decisions. To assist the technically incapable crowd, we propose a permission control framework based on crowdsourcing. At its core, our framework runs new apps under probation mode without granting their permission requests up-front. It provides recommendations on whether to accept or not the permission requests based on decisions from peer expert users. To seek expert users, we propose an expertise rating algorithm using a transitional Bayesian inference model. The recommendation is based on aggregated expert responses and their confidence level. As a complete framework design of the system, this thesis also includes a solution for Android app risks estimation based on behaviour analysis. To eliminate the negative impact from dishonest app owners, we also proposed a bot user detection to make it harder to utilize false recommendations through bot users to impact the overall recommendations. This work also covers a multi-view permission notification design to customize the app safety notification interface based on users' need and an app recommendation method to suggest safe and usable alternative apps to users.

Library research studies have provided evidence that teacher-librarians (TLs) impact student academic success; nevertheless, TLs statewide and internationally are at a critical juncture due to stakeholder groups' ambiguous perceptions regarding their influence on student achievement. The problem in this study involves a local independent school district's lack of conclusive evidence to demonstrate TLs' contribution to student achievement on standardized testing. The purpose of this study was to examine the perceptions of TLs, classroom teachers (CTs), and administrative staff (AS) concerning student achievement as instructed by local TLs. Using Piaget's cognitive theory and Mezirow's transformative learning theory, this qualitative case study explored the perceptions of 15 participants and acquired clarification regarding the TLs' instructional practice. The interview questions focused on perceptions of 5 CTs, 5 AS, and 5 TLs regarding the instructional role of TLs on students' academic success as well as the evidence provided by these stakeholders regarding the value of school libraries. Data collection with semi-structured interviews followed by an open coding thematic analysis revealed 7 themes: (1) involvement in curriculum, (2) flexibility of schedule, (3) preconceived misconceptions, (4) using an evidence-based practice approach, (5) collaboration, (6) access to materials, and (7) a conducive learning environment. The resulting project consisted of a policy recommendation created for augmenting stakeholder perceptions. The project contributes to social change by fostering an informed societal positive perception of the TLs' instructional influence on student academic achievement and by offering a measurable interpretation of the TLs' educational value to the learning community that may transform stakeholder perception locally and worldwide.

L'analyse et l'exploitation des préférences interviennent dans de nombreux domaines, comme l'économie, les sciences sociales ou encore la psychologie. Depuis quelques années, c'est l'e-commerce qui s'intéresse au sujet dans un contexte de personnalisation toujours plus poussée. Notre étude s'est portée sur la représentation et l'apprentissage de préférences sur des objets décrits par un ensemble d'attributs. Ces espaces combinatoires sont immenses, ce qui rend impossible en pratique la représentation in extenso d'un ordre de préférences sur leurs objets. C'est pour cette raison que furent construits des langages permettant de représenter de manière compacte des préférences sur ces espaces combinatoires. Notre objectif a été d'étudier plusieurs langages de représentation de préférences et l'apprentissage de préférences. Nous avons développé deux axes de recherche. Le premier axe est l'algorithme DRC, un algorithme d'inférence dans les réseaux bayésiens. Alors que les autres méthodes d'inférence utilisent le réseau bayésien comme unique source d'information, DRC exploite le fait qu'un réseau bayésien est souvent appris à partir d'un ensemble d'objets qui ont été choisis ou observés. Ces exemples sont une source d'information supplémentaire qui peut être utilisée lors de l'inférence. L'algorithme DRC, de ce fait, n'utilise que la structure du réseau bayésien, qui capture des indépendances conditionnelles entre attributs et estime les probabilités conditionnelles directement à partir du jeu de données. DRC est particulièrement adapté à une utilisation dans un contexte où les lois de probabilité évoluent mais où les indépendances conditionnelles ne changent pas. Le second axe de recherche est l'apprentissage de k-LP-trees à partir d'exemples d'objets vendus. Nous avons défini formellement ce problème et introduit un score et une distance adaptés. Nous avons obtenu des résultats théoriques intéressants, notamment un algorithme d'apprentissage de k-LP-trees qui converge avec assez d'exemples vers le modèle cible, un algorithme d'apprentissage de LP-tree linéaire optimal au sens où il minimise notre score, ainsi qu'un résultat sur le nombre d'exemples suffisants pour apprendre un " bon " LP-tree linéaire : il suffit d'avoir un nombre d'exemples qui dépend logarithmiquement du nombre d'attributs du problème. Enfin, une contribution expérimentale évalue différents langages dont nous apprenons des modèles à partir d'historiques de voitures vendues. Les modèles appris sont utilisés pour la recommandation de valeur en configuration interactive de voitures Renault. La configuration interactive est un processus de construction de produit où l'utilisateur choisit successivement une valeur pour chaque attribut. Nous évaluons la précision de la recommandation, c'est-à-dire la proportion des recommandations qui auraient été acceptées, et le temps de recommandation ; de plus, nous examinons les différents paramètres qui peuvent influer sur la qualité de la recommandation. Nos résultats sont concluants : les méthodes que nous avons évaluées, qu'elles proviennent de la littérature ou de nos contributions théoriques, sont bien assez rapides pour être utilisées en ligne et ont une précision très élevée, proche du maximum théorique. / The analysis and the exploitation of preferences occur in multiple domains, such as economics, humanities and psychology. E-commerce got interested in the subject a few years ago with the surge of product personalisation. Our study deals with the representation and the learning of preferences on objects described by a set of attributes. These combinatorial spaces are huge, which makes the representation of an ordering in extenso intractable. That's why preference representation languages have been built: they can represent preferences compactly on these huge spaces. In this dissertation, we study preference representation languages and preference learning.Our work focuses on two approaches. Our first approach led us to propose the DRC algorithm for inference in Bayesian networks. While other inference algorithms use the sole Bayesian network as a source of information, DRC makes use of the fact that Bayesian networks are often learnt from a set of examples either chosen or observed. Such examples are a valuable source of information that can be used during the inference. Based on this observation, DRC uses not only the Bayesian network structure that captures the conditional independences between attributes, but also the set of examples, by estimating the probabilities directly from it. DRC is particularly adapted to problems with a dynamic probability distribution but static conditional independences. Our second approach focuses on the learning of k-LP-trees from sold items examples. We formally define the problem and introduce a score and a distance adapted to it. Our theoretical results include a learning algorithm of k-LP-trees with a convergence property, a linear LP-tree algorithm minimising the score we defined and a sample complexity result: a number of examples logarithmic in the number of attributes is enough to learn a "good" linear LP-tree. We finally present an experimental contribution that evaluates different languages whose models are learnt from a car sales history. The models learnt are used to recommend values in interactive configuration of Renault cars. The interactive configuration is a process in which the user chooses a value, one attribute at a time. The recommendation precision (the proportion of recommendations that would have been accepted by the user) and the recommendation time are measured. Besides, the parameters that influence the recommendation quality are investigated. Our results are promising: these methods, described either in the literature or in our contributions, are fast enough for an on-line use and their success rate is high, even close to the theoretical maximum.

La facilitation est un élément central dans une prise de décision de groupe surtout en faisant l'usage des outils de nouvelle technologie. Le facilitateur, pour rendre sa tâche facile, a besoin des solutions de vote pour départager les décideurs afin d'arriver à des conclusions dans une prise de décision. Une procédure de vote consiste à déterminer à partir d’une méthode le vainqueur ou le gagnant d’un vote. Il y a plusieurs procédures de vote dont certaines sont difficiles à expliquer et qui peuvent élire différents candidats/options/alternatives proposées. Le meilleur choix est celui dont son élection est acceptée facilement par le groupe. Le vote dans la théorie du choix social est une discipline largement étudiée dont les principes sont souvent complexes et difficiles à expliquer lors d’une réunion de prise de décision. Les systèmes de recommandation sont de plus en plus populaires dans tous les domaines de science. Ils peuvent aider les utilisateurs qui n’ont pas suffisamment d’expérience ou de compétence nécessaires pour évaluer un nombre élevé de procédures de vote existantes. Un système de recommandation peut alléger le travail du facilitateur dans la recherche d’une procédure vote adéquate en fonction du contexte de prise de décisions. Le sujet de ce travail de recherche s’inscrit dans le champ de l’aide à la décision de groupe. La problématique consiste à contribuer au développement d’un système d’aide à la décision de groupe (Group Decision Support System : GDSS). La solution devra s’intégrer dans la plateforme logicielle actuellement développée à l’IRIT GRUS : GRoUp Support. / Facilitation is a central element in decision-making, especially when using new technology tools. The facilitator, to make his task easy, needs voting solutions to decide between decision-makers in order to reach conclusions in a decision-making process. A voting procedure consists of determining from a method the winner of a vote. There are several voting procedures, some of which are difficult to explain and which may elect different candidate/options/alternatives proposed. The best choice is the one whose election is easily accepted by the group. Voting in social choice theory is a widely studied discipline whose principles are often complex and difficult to explain at a decision-making meeting. Recommendation systems are becoming more and more popular in all fields of science. They can help users who do not have sufficient experience or competence to evaluate large numbers of existing voting procedures. A recommendation system can lighten the facilitator's workload in finding an appropriate voting procedure based on the decision-making context. The objective of this research work is to design such recommendation system. This work is in the field of group decision support. The issue is to contribute to the development of a Group Decision Support System (GDSS). The solution will have to be integrated into the software platform currently being developed at IRITGRUS: GRoUp Support.

With more and more images being uploaded to social networks each day, the resources for identifying a large portion of the world are available. However the tools to harness and utilize this information are not sufficient. This thesis presents a system, called PhacePhinder, which can build a face database from a social network and have it accessible from mobile devices. Through combining existing technologies, this is made possible. It also makes use of a fusion probabilistic latent semantic analysis to determine strong connections between users and content. Using this information we can determine the most meaningful social connection to a recognized person, allowing us to inform the user of how they know the person being recognized. We conduct a series of offline and user tests to verify our results and compare them to existing algorithms. We show, that through combining a user’s friendship information as well as picture occurrence information, we can make stronger recommendations than based on friendship alone. We demonstrate a working prototype that can identify a face from a picture taken from a mobile phone, using a database derived from images gathered directly from a social network, and return a meaningful social connection to the recognized face.

In recent years, music has become increasingly universal due to technological advances. All kinds of music have become more complex and a large amount around us. How recommending the music that user is interested in from a wide variety of music is the development intentions of the music recommendation system MRS (Music Recommendation System). In the recommending system, the most widely known is Content-based (CB) and Collaborative (COL). Chen et al. have proposed an alternative way that used CB and COL of music recommendation. The purpose of the CB method is to recommend the music objects that belong to the music groups the user is recently interested in. Each transaction is assigned a different weight, where the latest transaction has the highest weight. The preferences of users are derived from the access histories and recorded in profiles. Based on the collaborative approach, the purpose of the COL method is to provide unexpected findings due to the information sharing between relevant users. But in the CB method, the formula of computing music group weight pays much attention to the weight of the transaction. This will lead to the result that the group weight of music group B which appears once in the later transaction is larger than the group weight of the music group A which appears many times in the earlier transaction. In the COL method, they do not care the density of the group, where high density means that the transactions which the music group appears are close in the access history of the user. This will lead to the result that the supports of the groups which have different densities are the same, and then the users may be grouped together. Therefore, in this thesis, we propose the TICI (Transaction-Interest-Count-Interest) method to improve the CB method. Considering the two situations of the music group that user is interested in, the large count of music group and the appearance in the later transaction, we put two parameters: Count-Interest and Transaction-Interest in our TICI method to let users choose which weight they want to emphasize. Sometimes, people not only want the music object from one group. We extend the TICI method to find the group pair that the user is interested in. We use two thresholds: CountT and WeightT to decide which candidates can be in the large itemset. In our propose method, we have two possible ways to find the result. And we propose the DI (Density-Interest) method to improve the COL method. Our DI method calculates the supports of music groups and consider the distributions of appearances of the music group. From our simulation results, we show that our TICI method could provide better performance than the CB method. Moreover, our DI method also could provide better performance than the COL method.

Could the analysts¡¦ forecasting be the important investment decision of the naive investors? This is the significant issue of the study. The study shows the following, in the short run, recommendations have information value; in the long run, forecasting earnings have information value. And electronic industry is the most valuable of all industries in the long run and short run. Although recommendations also have information value in the long run, but the industry returns aren¡¦t consistent. In addition, analysts over predict about the forecasting earnings. Finally, the study also shows the following, forecasting price or recommendation has negative coefficient and statistically significant in large scale company. Because large scale companies are more attentive than small scale companies, and information superiority trader already get the information before analysts¡¦ release. So they can trade the stocks before analysts¡¦ release, naive investors can¡¦t get returns with the analysts¡¦ forecasting.

Targeting a small portion of customers for advertising has long been recognized by businesses. In this thesis we proposed a novel approach to promoting products with no prior transaction records. This approach starts with discovering the GP-association rules between customer types and product genres that had occurred frequently in transaction records. Customers are characterized by demographic attributes, some of these attributes have concept hierarchies and products can be generalized through some product taxonomy. Based on GP-association rules set, we developed a comprehensive algorithm to locating a short list of prospective customers for a given promotion product. The new approach was evaluated using the patron¡¦s circulation data from OPAC system of our university library. We measured the accuracy of estimated method and the effectiveness of targeted advertising in different parameters. The result shows that our approach achieved higher accuracy and effectiveness than other methods.

The rapid increase of available products and information on the Internet has created new problems for consumers. In stead of not having adequate alternatives, consumers have to spend a lot of effort in filtering and processing information. Overcoming information overload becomes a key issue for information search. As a result, information filtering and product recommendation become increasingly popular among on-line stores. These e-stores can collect user preference and use the information for product recommendation and personalized services. The purpose of recommendation systems is to increase consumers¡¦ purchase intentions, which may be affected by many factors. The objective of this study is to investigate factors that may affect the purchase intention of consumers. More specifically, the research adopts two theories, the elaboration likelihood model and the social influence theory, to build a research framework. We assume that the recommendation message affect consumer attitudes and intention through information and social influences. A laboratory experiment was conducted that use books and movies as two products to test the theory. The results indicate that purchase intention was affected by the attitude toward the recommended product and informational influence. The attitude toward the recommended product, informational influence, and normative social influence were affected by the type of the products and web comments on the product. Different recommendation approaches also affected consumers¡¦ perception of informational influence. The contribution of the research is two folds. First, we develop a theory that can be used to interpret the effect of different factors in the recommendation process. Second, the results have explored much insight into how product recommendation affects consumer attitude and purchase intention and can also be used in designing recommendation systems.

In this thesis, a content recommendation system has been developed. The system makes recommendations based on the preferences of the users on some aspects of the content and also preferences of similar users. The preferences of a user are extracted from the choices of that user made in the past. Similarities between users are defined by the similarities of their preferences. Such a system requires both qualified content and user information. The proposed system uses semantic user and content profiles to more effectively define the relationships between the two and make better inferences. An ontology is defined using the existing domain ontologies and the semi-structured data on the web. The system is implemented mainly for the movie domain in which well-defined ontologies and user information are easier to access.