Multilingual machine translation : a case study of Spanish-English reflexives

This dissertation describes a formal ism for mult i l ingual machine translat ion and its appl icat ion to the translation of reflexive constructions between Spanish and Engl ish. The language descr ipt ion is principle-based, with l inguist ic rules div ided between language-specific components and shared language-independent components. The principles define head projection and the licensing of attachments to the projection. Rules create l inguistic objects as tree structures, where nodes are represented as feature structures (attribute-value pairs). Feature unif ication, augmented wi th negative, disjunctive, and condit ional constraints, defines the feature content of the objects. Translat ion is accomplished by defining levels of representation based on morphological , syntactic, and semantic (predicate-argument) structures, and by defining structural transformations between levels. Language transfer is based on the Pr inc ip le of Semantic Compat ibi l i ty, in which semantic representations (trees and features) across languages are unifiable with each other. Us ing this formalism, rule components for Engl ish and Spanish are defined which maximize rule-sharing; only ten phrase structure rules are required for a substantial subset of the Engl ish and Spanish languages. A l l grammat ica l relations are expressed in terms of local trees (root node and immediate daughters). Arguments and modifiers are licensed in canonical posit ion, and displaced arguments may appear either in subject or c l i t ic posit ion. A displaced argument is associated wi th its predicate not by movement but by unify ing features wi th in a chain structure spanning al l of the local trees between the argument and the predicate. G iven this l inguistic model , an implementat ion of reflexives is described in which a reflexive pronoun discharges either an internal or an external argument. If an internal argument is discharged, a personal reflexive construction results, as in Juan se vio ' Juan saw h imse l f . If an external argument is discharged, a nonpersonal reflexive construction results, as in Se venden pehodicos 'Newspapers are sold 7 . In both personal and nonpersonal reflexive constructions, the sentential subject, whether lexical or nul l , binds the reflexive. In the nonpersonal reflexive construct ion, a pleonastic null subject binds the reflexive. A Reflexive Pr inc ip le , implemented over local trees, determines when a pronoun is reflexive and when not, depending on the binding potential of an undischarged external argument.