This paper proposes a model for short-term content adaptation whose aim is to satisfy the contingent needs of users by adjusting the information a web-application provides on the basis of a short-term user profile. The mathematical model results in the design of an adaptive filter that profiles users by observing their queries to the application and that adjusts the answers of the application according to the inferred user needs. Also, the mathematical model ensures the correctness of the filter, that is, the filter is guaranteed to exhibit a coherent short-term adaptive behaviour. Categories and Subject Descriptors