ABSTRACT
Natural language understanding and natural language generation systems could have the same knowledge of language. Adopting a bidirectional grammar for a language-understanding and -generation system implies certain constraints on the system's design. Because the grammar for such a system must consist of declarative rules to be interpreted, it must provide exactly the same information to both parsing and generation processes. The strategic component of the system is the part that produces a logical form plus a set of functional features, while the tactical component realizes the strategic specification as an utterance. Comprehension and generation are the two complementary aspects of natural language processing. Language, like vision, may be so tied up with the nature of the human mind and its computational properties that no design that goes against those properties will ever be more than a special purpose hack.
