This paper describe mixed-initiative dialc form-filling paradign hierarchy that contai Along with the slot I that allows for adapi on the success or fai zoom-in to more de level questions. The distribution of i the granularity of thc mine the right granul take into account the and the knowledge , suitable in situations cases, the user may However, giving the behaviour less predii on speech-understanc lower-level question! the user supplies U switch to higher-leve 1 Many practical dia filling paradigm. 7 the user, the syste This information i and questions can t One of the merits allows a clear disti changing informat task is described bl values that they m: the order in which ing of slot values, and uncertainties t ticipants attempt t c strategies can be r( that developing a i limited to specifyir tics.0-7803-5028-6/98/$ ABSTRACT in architecture that supports adaptive le. It is based on a generalisation of the lather than a flat slot structure, we use a slots at various levels of abstraction. rarchy, a question hierarchy is defined : mixed-initiative dialogue. Depending -e of certain questions, the system can led questions, or zoom-out to higheriative in dialogue is closely related to nformation that is asked for. To deterry level for system questions we have to fluences on user freedom, predictability the user. Giving the user initiative is iere the user knows what to do. In such 'e all relevant information in one turn. ser more initiative tends to make his ble' and therefore increases the chance g errors. The system should switch to vhen higher-level ones fail, and when olicited information, the system can iestions.
TRODUCTIONcue systems are based on the formperform some action on behalf of needs information from the user. ,epresented as a fixed set of slots, isked for each slot. the slot-filling paradigm is that it tion between the dialogue task (ex-I) and the dialogue strategy. The le slots themselves and the possible get. The strategy is concerned with its are discussed, and with ground-:. with inconsistencies, ambiguities t can arise when the dialogue par3uild a common ground. Dialogue ;ed for many different domains, so dogue system for a new domain is a new set of slots and their seman-00 0 1998 IEEE A drawback of the slot-filling paradigm as it stands, is that it results in rather rigid dialogues. The "model dialogue" within the slot-filling paradigm is one in which a number of system questions are interleaved with answers from the user, each answer answering just the question that was asked by the system. In spoken human-human dialogues, this kind of dialogue is very rare; People ask questions that refer to concepts that involve more than one slot, and they are often over-informative and say things which they believe are relevant, even when they aren't asked for. More so, they use these devices intelligently, using high-level concepts to open the dialogue, and zooming into details when problems arise. Many systems (for instance, the one described by Aust et al. [[I]]) are able to ask questions involving ...