@article { paiva95, abstract = {In this paper we will describe, outline and exemplify the functionalities and architecture of a User and Learner Modeling System called TAGUS (within the project "Theory and Applications for General User/Learner-modeling Systems"). TAGUS was developed with two main goals: (1) to develop a framework to represent models of users and learners where the meta-cognitive activities of learners were taken into account; and (2) to try to capture in a system some general mechanisms and techniques for user and learner modeling in the form of services. The basic idea of TAGUS is to achieve a kind of workbench where some techniques and approaches for user and learner modeling are implemented and applied. TAGUS provides a set of services, to be used by people testing methods or by applications using user models. These services, provided to external agents, embed some mechanisms for maintaining models of the users and learners. Thus, TAGUS plays a role of a user and learner modeling server. To achieve this goal, we first identified some basic mechanisms in user and learner modeling, and based Oll them we established a general modeling cycle. This cycle involves two main stages: the acquisition and the maintenance of the model. The different strategies and techniques are specified in separate modules or knowledge sources in TAGUS, which uses them to execute parts of that cycle. The architecture of TAGUS is composed of: a User or Learner Model (ULM); a set of maintenance functions; an acquisition engine; a reason maintenance system; a meta-reasoner and two interfaces. At the same time, TAGUS provides a language for defining the models of the users and learners, which can be used with different techniques, in order to test the models and simulate them in the system. This language is used not only to represent the models, but also as a way of establishing the communication between TAGUS and its environment. TAGUS was built incrementally around a set of core functions for the manipulation of the User or Learner Model (ULM). Other layers of this set were built where the last layer corresponds to the services TAGUS supplies. }, journal = {User Modeling and User-Adapted Interaction}, keywords = {User modeling}, pages = {197-226}, title = {TAGUS - A User and Learner Modeling Workbench}, volume = {4}, year = {1995}, author = {Ana Paiva} }