Following Austin's work, some theories have attempted to develop the idea that utterances can be understood as actions. In Artificial Intelligence there has been a body of work trying to do this in terms of joint planning. Previous work has been of two kinds: building up from the basic units of utterances and speech acts, or building down from external goals and trying to model connected sequences of utterances i.e. conversation. This thesis extends the latter tradition. After an initial empirical investigation, two new claims are made. Firstly the computer program, listed in the appendix, shows how time slicing changes dialogue outcome in interesting ways. Secondly an exhaustive planning framework for Power's robot world provides agents with better conversational skills than those reported so far. Finally the thesis discusses the drawbacks encountered in the empirical investigation and proposes a new basic unit, NEOTELL, a single generic unit of mutual agreement out of which whole conversations can be formed and an agents external goals achieved
