Computational stylistics for natural language translation
Chrysanne Di Marco, Graeme Hirst · 1990
The problem of style is highly relevant to machine translation (scMT), but current systems deal only superficially, if at all, with the preservation of stylistic effects. At best, scMT output is syntactically correct but aims no higher than a strict uniformity in style. The expressive effects contained in the source text, together with their associated meaning, are lost. I have developed an approach to the computational treatment of style that incorporates three selected components--lexical, syntactic, and semantic--and focuses on certain aspects of syntactic style. I have designed and implemented the foundations of a computational model of goal-directed stylistics that could serve as the basis of a system to preserve style in French-to-English translation. First, I developed a vocabulary of style that contains both primitive and abstract elements of style. The primitive elements describe the stylistic effects of individual sentence components. These elements are combined into patterns that are described by a stylistic meta-language, the abstract elements, that define the stylistic effects common to a group of sentences. These elements have as their basis the notions of concord and discord, for it is my contention that style is created by patterns of concord and discord giving an overall integrated arrangement. These patterns are built from the abstract elements and associated with specific stylistic goals such as clarity or concreteness. Thus, I have developed a syntactic stylistic grammar at three interrelated levels of description: primitive shapes, abstract elements, stylistic goals. Grammars for both French and English have been constructed, using the same vocabulary and the same development methodology. As well, Mark Ryan, a colleague at the University of Toronto, has constructed a semantic stylistic grammar that uses this vocabulary and methodology. Parsers that implement these grammars have also been implemented. Together, the English and French parsers could form the basis of a system that could preserve many aspects of style in translation. The incorporation of stylistic analysis into scMT systems should significantly reduce the current reliance on human post-editing and improve the quality of scMT output.