Extending the State of the Art
This book has presented a computational model for integrated dialog processing. The primary contributions of this research follow. • A mechanism (the Missing Axiom Theory) for integrating subtheories that each address an independently studied subproblem of dialog processing (i.e. interactive task processing, the role of language, user modeling, and exploiting dialog expectation for contextual interpretation and plan recognition). • A computational theory for variable initiative behavior that enables a system to vary its responses at any given moment according to its level of initiative. • Detailed experimental results from the usage of a spoken natural language dialog system that illustrate the viability of the theory and identify behavioral differences of users as a function of their experience and initiative level. This chapter provides a concluding critique, which identifies areas of ongoing work and offers some advice for readers interested in developing their own spoken natural language dialog systems. This section describes important issues we did not successfully address in this research because either (1) we studied the problem but do not as yet have a satisfactory answer; or (2) it was not necessary to investigate the problem for the current system. Regardless of the reason, incorporating solutions to these problems is needed to strengthen the overall model. In section 4.7.3 we have already discussed the difficulties in determining when and how to change the level of initiative during a dialog as well as the problems in maintaining coherence when such a change occurs. Ongoing work in this area is being conducted by Guinn [Gui93]. His model for setting the initiative is based on the idea of “evaluating which participant is better capable of directing the solution of a goal by an examination of the user models of the two participants.” He provides a formula for estimating the competence of a dialog participant based on a probabilistic model of the participant’s knowledge about the domain. Using this formula, Guinn has conducted extensive experimental simulations testing four different methods of selecting initiative.