Conversation via Dialogue Management

Dialogue systems carry out conversations with users in natural language, whether spoken or typed. The main tasks performed by dialogue systems are language interpretation, language generation, and dialogue management. Natural language interpretation and generation are topics onto themselves and we will not discuss them here; for two introductory texts, see [9] and [42]. To enable a focus on user modeling, our system allows moderately complex user utterances but has a pre-coded set of system utterances, as discussed further in Section 3.3. The simplest dialogue managers are based on finite-state automata in which the states correspond to questions and arcs correspond to actions that depend on a user-provided response [75,81]. These systems support what are called fixed- or system-initiative conversations, in which only one of the participants controls the actions, whether it be the system helping the user or the user asking questions of the system. Next in complexity are frame- or template-based systems in which questions can be asked and answered in any order (Bobrow et al., 1977). Next, true mixed-initiative systems allow either dialogue participant to contribute to the interaction as their knowledge permits (Allen, 1999; Haller & McRoy, 1998; Pieraccini, Levin, & Eckert, 1997). Thus, the conversational focus can change at any time due to the user's (or system's) initiative of that change. Finally, some different approaches that support sophisticated dialogues include plan-based systems (Allen et al., 1995; Cohen & Perrault, 1979) and systems using models of rational interaction [66]. To allow reasonably complex conversations while keeping the system design straightforward, we chose a frame-based approach to dialogue management. Thus, the ADAPTIVE PLACE ADVISOR allows more conversational flexibility than a fully system-initiative paradigm would allow. Users can fill in attributes other than or in addition to those suggested by the system. However, they cannot force the system to transition to new subtasks, nor can the system negotiate with users to determine which participant should take the initiative.