Results Context specificity Valid mappings partitioning check Figure 10.7 The contextualization service. two sets (called POS and NEG) containing, respectively, relevant and irrelevant results for each context. The mapping initialization step consists in initializing the possible mappings between the user profile predicates and the application contexts. This task is achieved by evaluating the score of each profile preference in each context. This is done by computing the occurrence frequencies of each profile predicate in the POS and NEG sets. Then, candidate mappings are created with a weight computed from their frequency. Finally, the context specificity check phase prunes mappings that relate the same profile predicate to all contexts. Indeed, these mappings concern profile predicates that do not have to be contextualized as they have to be considered in all contexts. The result of this step is a set of valid mappings representing relationships between the user profile and the application contexts. 10.3.2 Online Services Online services are used at application runtime to provide effective personalization to the application. They are obviously based on results of offline services. 10.3.2.1 Binding Service The binding service exploits the mappings generated by the contextualization service to derive the operational profile. It consists in identifying the parts of the user pro- file that are related to a given context. Basically, the binding filters profile prefer- ences that are not relevant to the active context of the user, and in adapting the remaining ones to this context. An interesting problem with the binding service is the computation of the final preferences taking into account both the initial value of the preference and the weight computed by the contextualization service. Personalization Paradigm in Service Delivery Platforms For instance, if a user is interested in Java programming at work but not at home, this preference has not to be used in the home context. It is thus filtered before applying pe