An Approach to Increasing Programming Efficiency in Plan-Based Dialogue Systems

In this paper we use software engineering criteria to evaluate possible changes to a dialogue-based ITS. We have developed a prototype ITS, CAPE, that uses the APE reactive planning system as a platform for developing a small ITS based on CIRCSIM-Tutor, an existing medical tutor. CAPE primitives are untyped, like relations in a Prolog program, and can include elements of discourse, domain and pedagogical reasoning. The resulting system is fast, robust, and easy to use and to extend. However, it requires a large number of plan operators to cover a relatively small topic area. We analyze the CAPE plan operators with respect to their major system function in order to understand which functions are contributing to the size of the plan library. We discuss proposed changes to the planner and the plan library, considering the effect of these proposed improvements on the number of plan operators required, amount of related procedural code required, authoring speed, legibility of the resulting system, coverage of the domain, and portability. We conclude with recommendations for further empirical studies.