Semantic-Syntax-Directed Translation

This paper examines the role which “semantics” can play in language translation. When formally defined at all, the meanings of sentences have been used in the past only to prove properties about translators (usually “correctness”). A new family of semantic-syntax-directed translators is presented here which “actively” use semantic information at translation time to help induce the translation. The family members display properties quite distinct from those of purely syntax-directed translators, with some semantic-syntax-directed translators enumerating every “correct” translation of a source sentence. Translations are defined between a general form of “phrase-structure language” which has both an underlying context-free grammar and a function-theoretic semantics based on Knuth's attributed grammar and Buttelmann's phrase-structure semantics. “Semantic deviance” is applied to syntax-directed methods for the first time. Both strings and their parses may be deviant; i.e., meaningless. The translators “filter” deviant strings and parse trees form entering or leaving the tree transducer of the translator. A second form of semantic-syntax-directed translator maps parse trees of source sentences to parse trees of sentences in the target language as a function of both the syntactic structure of the source parse tree and the values of attributes of its nodes.