Rank Optimization of Personalized Search

Augmenting the global ranking based on the linkage structure of the Web is one of the popular approaches in data engineering community today for enhancing the search and ranking quality of Web information systems. This is typically done through automated learning of user interests and re-ranking of search results through semantic based personalization. In this paper, we propose a query context window (QCW) based framework for Selective uTilization of search history in personalized leArning and re-Ranking (STAR). We conduct extensive experiments to compare our STAR approach with the popular directory-based search methods (e.g., Google Directory search) and the general model of most existing re-ranking schemes of personalized search. Our experimental results show that the proposed STAR framework can effectively capture user-specific query-dependent personalization and improve the accuracy of personalized search over existing approaches

Building and applying a Concept Hierarchy Representation of a user profile

Term dependence is a natural consequence of language use. Its successful representation has been a long standing goal for Information Retrieval research. We present a methodology for the construction of a concept hierarchy that takes into account the three basic dimensions of term dependence. We also introduce a document evaluation function that allows the use of the concept hierarchy as a user profile for Information Filtering. Initial experimental results indicate that this is a promising approach for incorporating term dependence in the way documents are filtered

Personality representation: predicting behaviour for personalised learning support

The need for personalised support systems comes from the growing number of students that are being supported within institutions with shrinking resources. Over the last decade the use of computers and the Internet within education has become more predominant. This opens up a range of possibilities in regard to spreading that resource further and more effectively. Previous attempts to create automated systems such as intelligent tutoring systems and learning companions have been criticised for being pedagogically ineffective and relying on large knowledge sources which restrict their domain of application. More recent work on adaptive hypermedia has resolved some of these issues but has been criticised for the lack of support scope, focusing on learning paths and alternative content presentation. The student model used within these systems is also of limited scope and often based on learning history or learning styles.This research examines the potential of using a personality theory as the basis for a personalisation mechanism within an educational support system. The automated support system is designed to utilise a personality based profile to predict student behaviour. This prediction is then used to select the most appropriate feedback from a selection of reflective hints for students performing lab based programming activities. The rationale for the use of personality is simply that this is the concept psychologists use for identifying individual differences and similarities which are expressed in everyday behaviour. Therefore the research has investigated how these characteristics can be modelled in order to provide a fundamental understanding of the student user and thus be able to provide tailored support. As personality is used to describe individuals across many situations and behaviours, the use of such at the core of a personalisation mechanism may overcome the issues of scope experienced by previous methods.This research poses the following question: can a representation of personality be used to predict behaviour within a software system, in such a way, as to be able to personalise support?Putting forward the central claim that it is feasible to capture and represent personality within a software system for the purpose of personalising services.The research uses a mixed methods approach including a number and combination of quantitative and qualitative methods for both investigation and determining the feasibility of this approach.The main contribution of the thesis has been the development of a set of profiling models from psychological theories, which account for both individual differences and group similarities, as a means of personalising services. These are then applied to the development of a prototype system which utilises a personality based profile. The evidence from the evaluation of the developed prototype system has demonstrated an ability to predict student behaviour with limited success and personalise support.The limitations of the evaluation study and implementation difficulties suggest that the approach taken in this research is not feasible. Further research and exploration is required –particularly in the application to a subject area outside that of programming

Usagers & Recherche d'Information

La recherche d'information est confrontée à une variété de plus en plus importante tant en termes d'usagers, de tâches à remplir, d'outils.... Face à cette hétérogénéité de nombreux travaux, s'attachent à améliorer la recherche d'information par le biais d'approches adaptatives, de systèmes de recommandation... Mes travaux s'inscrivent dans ce cadre et apportent un éclairage essentiellement porté sur l'usager et ses activités et plus particulièrement sur la recherche d'information. Les résultats correspondent à 3 angles d'investigation nous permettant d'aborder cette problématique de l'hétérogénéité en Recherche d'Information

Contribution à la définition de modèles de recherche d'information flexibles basés sur les CP-Nets

This thesis addresses two main problems in IR: automatic query weighting and document semantic indexing. Our global contribution consists on the definition of a theoretical flexible information retrieval (IR) model based on CP-Nets. The CP-Net formalism is used for the graphical representation of flexible queries expressing qualitative preferences and for automatic weighting of such queries. Furthermore, the CP-Net formalism is used as an indexing language in order to represent document representative concepts and related relations in a roughly compact way. Concepts are identified by projection on WordNet. Concept relations are discovered by means of semantic association rules. A query evaluation mechanism based on CP-Nets graph similarity is also proposed.Ce travail de thèse adresse deux principaux problèmes en recherche d'information : (1) la formalisation automatique des préférences utilisateur, (ou la pondération automatique de requêtes) et (2) l'indexation sémantique. Dans notre première contribution, nous proposons une approche de recherche d'information (RI) flexible fondée sur l'utilisation des CP-Nets (Conditional Preferences Networks). Le formalisme CP-Net est utilisé d'une part, pour la représentation graphique de requêtes flexibles exprimant des préférences qualitatives et d'autre part pour l'évaluation flexible de la pertinence des documents. Pour l'utilisateur, l'expression de préférences qualitatives est plus simple et plus intuitive que la formulation de poids numériques les quantifiant. Cependant, un système automatisé raisonnerait plus simplement sur des poids ordinaux. Nous proposons alors une approche de pondération automatique des requêtes par quantification des CP-Nets correspondants par des valeurs d'utilité. Cette quantification conduit à un UCP-Net qui correspond à une requête booléenne pondérée. Une utilisation des CP-Nets est également proposée pour la représentation des documents dans la perspective d'une évaluation flexible des requêtes ainsi pondéreés. Dans notre seconde contribution, nous proposons une approche d'indexation conceptuelle basée sur les CP-Nets. Nous proposons d'utiliser le formalisme CP-Net comme langage d'indexation afin de représenter les concepts et les relations conditionnelles entre eux d'une manière relativement compacte. Les noeuds du CP-Net sont les concepts représentatifs du contenu du document et les relations entre ces noeuds expriment les associations conditionnelles qui les lient. Notre contribution porte sur un double aspect : d'une part, nous proposons une approche d'extraction des concepts en utilisant WordNet. Les concepts résultants forment les noeuds du CP-Net. D'autre part, nous proposons d'étendre et d'utiliser la technique de règles d'association afin de découvrir les relations conditionnelles entre les concepts noeuds du CP-Nets. Nous proposons enfin un mécanisme d'évaluation des requêtes basé sur l'appariement de graphes (les CP-Nets document et requête en l'occurrence)