Case-based to content-based user model mediation

Systems providing personalized services to users have a need to build and maintain a User Model (UM). However, at the onset of providing services, such a system has no prior knowledge about a user and it may benefit from information imported from external sources. Due to lack of standards in the representation of UMs, commercial competition, and privacy issues, distinct personalized service-providing systems build their own specific models and store their information in incompatible manners. Thus, although much data on a specific user might exist in other systems; it is typically unavailable for use in the initial phase of the given system. This work puts forward the design of a user model mediation idea. This is demonstrated in an initial implementation in a specific system (Museum Visitors' guide system) under the PIL project, where the user is modelled by a "bag of words" vector and the initial information is imported from a case-based modelled user (in an external trip planning system).