This report describes the organization and content of lexical information required for the task of machine translation. In particular, the lexical-conceptual basis for UNITRAN, an implemented machine translation system, will be described. UNITRAN uses an underlying form called lexical conceptual structure to perform lexical selection and syntactic realization. Lexical word entries have two levels of description: the first is an underlying lexical-semantic representation that is derived from hierarchically organized primitives, and the second is a mapping from this representation to a corresponding syntactic structure. The interaction of these two levels will be discussed and the lexical selection and syntactic realization processes will be described.

This report describes the UNITRAN (UNIversal TRANslator) system, an implementation of a principle-based approach to natural language translation. The system is "interlingual", i.e., the model is based on universal principles that hold across all languages; the distinctions among languages are handled by settings of parameters associated with the universal principles. Interaction effects of linguistic principles are handled by the syste so that the programmer does not need to specifically spell out the details of rule applications. Only a small set of principles covers all languages; thus, the unmanageable grammar size of alternative approaches is no longer a problem.