rsonalization. The binding service takes as input a user profile, the set of mappings issued from the contextualization, and the current user context. It returns the contextualized profiles that have to be considered by the application in the current context. Figure 10.8 gives an overview of the process. The profile content selection step consists in selecting profile preferences that have to be taken into account in the actual context. This corresponds to the union of noncontextualized preferences and preferences related to the current context. The mappings score considering step transforms the contextualized user prefer- ences into classic preferences. It consists in merging the initial preferences with the weight computed by the contextualization service. 10.3.2.2 Matching Services The matching service allows capturing the semantic similarity between two con- cepts. The similarity value can take into account, for example, the structure of concepts, user ratings, or ontologies describing the concepts. In our context, matching algorithms can be applied to several kinds of con- cepts. The matching between two user profiles can be used in a collaborative rec- ommender system to find similar users. The matching between a profile and a content has application for content-based recommendation. The matching between two contents can also be used to find similar products. Finally, the matching between two contexts is used in context-aware applications. User profile User profile Mappings Contextual M(Pu, C) profile content Profile content Mappings score selection consideration Actual user context Cj Figure 10.8 The binding service. Service Delivery Platforms 10.3.2.3 Query Reformulation Query reformulation is a high-level service which enables personalizing a query processing with respect to a given user profile [31]. This service conforms to the fol- lowing assumptions: (1) the users interact with a mediation system where mappings between the virtual schema and the source schemas are defined in a Local As View manner, (