AHAM: A Reference Model to Support Adaptive Hypermedia Authoring

Hypermedia applications generally contain a rich (hyper)link structure. For users of a hypermedia application the richness of this link structure can generate comprehension and orientation problems. Adaptive techniques have been used by a number of researchers [see e.g. 1,2,4,5,8,11,12,15,16,17] in an attempt to offer guidance through and orientation support for rich link structures. The majority of these adaptive hypermedia systems (AHS) have been used in educational applications, although some on-line information systems (or "kiosk"-systems) and information retrieval systems have been made adaptive as well. In this paper we describe a reference model for adaptive hypermedia applications, called AHAM, which encompasses most adaptive features supported by adaptive systems that exist today or that are being developed (and have been published about). The model uses "educational terminology", but this does not imply that we would preclude other types of applications. Key aspects in AHAM are: • The adaptation is based on a domain model, a user model and a teaching model which consists of pedagogical rules. We give a formal definition of each of these (sub)models. • We distinguish the notions of concept and page. In several AHS these notions are confused. • We provide a formalism which lets authors write pedagogical rules (about concepts) in such a way that they can be applied automatically. • The model is specifically designed to make it easy to develop authoring tools for it. • AHAM supports constructing the user model not only from the user's reading and navigation, but also from external sources, such as tests. This feature is useful for exchanging parts of a user model between different AHS. We illustrate various aspects of AHAM by means of the AHA system, used in distance learning applications and a kiosk information system at the Eindhoven University of Technology.