'If you've heard it, you can say it' - Towards an Account of Expressibility

We have begun a project to automatically create the lexico-syntactic resources for a microplanner as a side-effect of running a domain-specific language understanding system. The resources are parameterized synchronous TAG Derivation Trees. Since the KB is assembled from the information in the texts that these resources are abstracted from, it will decompose along those same lines when used for generation. As all possible ways of expressing each concept are pre-organized into general patterns known to be linguistically-valid (they were observed in natural text), we obtain an architectural account for expressibility.