This paper describes how a language-planning system can produce natural-language referring expressions that satisfy multiple goals. It describes a formal representation for reasoning about several agents' mutual knowledge using possible-worlds semantics and the general organization of a system that uses the formalism to reason about plans combining physical and linguistic actions at different levels of abstraction. It discusses the planning of concept activation actions that are realized by definite referring expressions in the planned utterances, and shows how it is possible to integrate physical actions for communicating intentions with linguistic actions, resulting in plans that include pointing as one.
