Dialogue-based user models

The paper investigates several approaches to user modeling in natural-language dialogue systems. First, reasons are pointed out why user modeling has become so important in the last few years, and definitions are proposed for the notions of "user model" and "user modeling component." Then, techniques for constructing user models in the course of a dialogue are presented and recent proposals for representing a wide range of assumptions about a user\´s beliefs and goals in a system\´s knowledge base are surveyed. Examples for the application of user models in systems developed to date are presented, and some social implications are discussed. Finally, unsolved problems like coping with collective beliefs or resource-limited processes are investigated, and prospects for application-oriented research are outlined.