Abstract: A method filters natural language output including fixed phrases by determining sequentially, for each fixed phrase, whether the fixed phrase has occurred in a discourse history. The fixed phrase is passed to a target component if the fixed phrase does not occur in the discourse history. If the fixed phrase does occur in the discourse history, a subsumption lattice is searched for an expressive type associated with the fixed phrase that is licensed in a context of the discourse history. The fixed phrase is converted to a filtered phrase according a realization method of the licensed expressive type and the filtered phrase is passed to the target component.

Abstract: A method for constructing a dynamic vocabulary for a speech recognizer used with a database of indexed documents. Key words are first extracted from each of the documents in the database as the documents are indexed. The extracted key words are than used to dynamically construct the vocabulary of the speech recognizer or a search engine.