Representing and reasoning about goal-directed
actions is necessary in order for autonomous
agents to act in or understand the commonsense
world. This paper provides a formal theory of in-
tentional action based on Bratman's characteriza-
tion of intention [Bratman, 1987, Bratman, 1990].
Our formalization profits from the the formaliza-
tion of Bratman's theory developed by Cohen and
Levesque [l990a, 1990bJ. W e review their formal-
ization and illustrate its weaknesses. Using Allen's
temporal logic [Allen, 1984] , w e construct a for-
malization that satisfies Bratman's desiderata for
an acceptable theory of intentional action. W e in-
troduce a characterization of success and failure of
intentional action and show that our richer theory
of time allows us to formalize more complex inten-
tional actions, particularly those with deadlines.
Finally, we argue that the use of a syntactic theory
of belief allows us to accommodatea more descrip-
tive theory of intentional action by fallible agents.
Our work has relevance to multi-agent planning,
speech-act processing and narrative understand-
ing. W e are using this theory to representing the
content of narratives and to constructing and un-
derstanding description-based communication.
