Natural language interfaces require dialogue models that
allow for robust, habitable and
efficient interaction. This paper presents such a model for dialogue management
for natural
language interfaces. The model is based on empirical studies of human computer
interaction
in various simple service applications. It is shown that for applications
belonging to this class
the dialogue can be handled using fairly simple means. The interaction
can be modeled in a
dialogue grammar with information on the functional role of an utterance
as conveyed in the
linguistic structure. Focusing is handled using dialogue objects recorded
in a dialogue tree
representing the constituents of the dialogue. The dialogue objects in
the dialogue tree can be
accessed by the various modules for interpretation, generation and background
system access.
Focused entities are modeled in entities pertaining to objects or sets
of objects, and related
domain concept information; properties of the domain objects. A simple
copying principle,
where a new dialogue object's focal parameters are instantiated with
information from the
preceding dialogue object, accounts for most context dependent utterances.
The action to
be carried out by the interface is determined on the basis of how the objects
and related
properties are specified. This in turn depends on information presented
in the user utterance,
context information from the dialogue tree and information in the domain
model. The use of
dialogue objects facilitates customization to the sublanguage
utilized in a specific application.
The framework has successfully been applied to various background systems
and interaction
modalities. In the paper results from the customization of the dialogue
manager to three
typed interaction applications are presented together with results from
applying the model to
two applications utilizing spoken interaction.