An adaptive user interface relies, to a large extent, upon an adequate user model (e.g., a representationof user-expertise). However, building a user model may be a tedious and time consuming task that willrender such an interface unattractive to developers. We thus need an effective means of inferring the user model at low cost. In this paper, we describe a technique for automatically inferring a fine-grain model of a user’s knowledge state based on a small number of observations. With this approach, the domain of knowledge to be evaluated is represented as a network of nodes (knowledge units—KU) and links (implications) induced from empirical user profiles. The user knowledge state is specified as a set of weights attached to the knowledge units that indicate the likelihood of mastery. These weights are updated every time a knowledge unit is reassigned a new weight (e.g., by a question-and-answer process). The updating scheme is based on the Dempster-Shafer algorithm. A User ...