  In more recent work, Matthew Stone shows in  Stone 1998  how modal logic can inform the complex reasoning involved in natural language generation. Generating a coherent, appropriately phrased text that usefully performs a task-oriented communication task is difficult to formalize because it requires the integration of complex and sophisticated domain information with discourse planning, user modeling, and linguistic constraints. Stone shows that modal logic can be used to modularize the formalization of the information required in this task; he also shows how modal theorem proving can be used to implement the reasoning.