  We show that in modeling social interaction, particularly dialogue, the
attitude of obligation can be a useful adjunct to the popularly considered
attitudes of belief, goal, and intention and their mutual and shared
counterparts. In particular, we show how discourse obligations can be used to
account in a natural manner for the connection between a question and its
answer in dialogue and how obligations can be used along with other parts of
the discourse context to extend the coverage of a dialogue system.
