Lifelong User Modelling Goals, Issues and Challenges

The combination of low and falling costs of storage, combined with increasingly pervasive and ubiquitous computing are creating the possibility of very long term user modelling. This paper explores some of the fundamental questions about the nature of a lifelong user model. It begins by exploring the relationship between the new goals that lifelong user models can support and the concomitant issues and challenges. We then explore the nature of what belongs in the user model, and what does not. From these foundations of the goals that the lifelong user model must serve, we discuss drivers for the design of systems which implement lifelong user models. We conclude with discussion of broad issues that follow from our analysis, proposing a roadmap for research needed to achieve lifelong user models.