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A scheme for syntax-directed translation that mirrors compositional model-theoretic semantics is discussed. The scheme is the basis for an English translation system called PArR and was used to specify a semantically interesting fragment of English, including such constructs as tense, aspect, modals, and various iexically controlled verb complement structures. PATR was embedded in a question-answering system that replied appropriately to questions requiring the computation of logical entailments. . | TRANSLATING ENGLISH INTO LOGICAL FORM Stanley J. Rosenschein Stuart M. Shieber Artificial Intelligence Center SRI International 333 Ravenswood Avenue Menlo Park CA 94025 ABSTRACT A scheme for syntax-directed translation that mirrors compositional model-theoretic semantics is discussed. The scheme is the basis for an English translation system called PATR and was used to specify a semantically interesting fragment of English including such constructs as tense aspect modals and various lexically controlled verb complement structures PATR was embedded in a question-answering system that replied appropriately to questions requiring the computation of logical entailments. I INTRODUCTION When contemporary linguists and philosophers speak of semantics they usually mean model-theoretic semantics mathematical devices for associating truth conditions with sentences. Computational linguists on the other hand often use the term semantics to denote a phase of processing in which a data structure e.g. a formula or network is constructed to represent the meaning of a sentence and serve as input to later phases of processing. A better name for this process might be translation or transduction. Whether one takes semantics to be about model theory or translation the fact remains that natural languages are marked by a wealth of complex constructions such as tense aspect moods plurals modality ad-verbials degree terms and sentential complements that make semantic specification a complex and challenging endeavor. Computer scientists faced with the problem of managing software complexity have developed strict design disciplines in their programming methodologies. One might speculate that a similar requirement for manageability has led linguists since Montague at least to follow a discipline of strict compositionality in semantic specification even though model-theoretic semantics per se does not demand it. Compositionality requires that the meaning of a phrase be a function of the .
