How Features Resolve Syntactic Ambiguity

Ambiguity is a pervasive and important as-pect of natural language. Ambiguities, which are disambiguated by context, contribute powerfully to the expressiveness of natural language as com-pared to formal languages. In computational systems using natural language, problems of prop-erly controlling ambiguity are particularly large, partially because of the necessity to circumvent parsings due to multiple orderings in the appli-cation of rules. Features, that is, subcategorizations of parts-of-speech, constitute an effective means for controlling syntactic ambiguity through order-ing the hierarchical organization of syntactic con-stituents. This is the solution adopted for con-trolling ambiguity in REL English, which is part of the REL (Rapidly Extensible Language) System. REL is a total software system for faciiitating man/machine communications. The efficiency of processing natural language in REL English is achieved both by the detailed syntactic aspects which are incorporated into the REL English grammar, and by means of the particular imple-mentation for processing features in the parsing algorithm. KEY WORDS AND PHRASE