Generating Clausal Coordinate Ellipsis Multilingually: A Uniform Approach Based on Postediting

Abstract

Present-day sentence generators are often incapable of producing a wide variety of well-formed elliptical versions of coordinated clauses, in particular, of combined elliptical phenomena (Gapping, Forward and Backward Conjunction Reduction, etc.). The applicability of the various types of clausal coordinate ellipsis (CCE) presupposes detailed comparisons of the syntactic properties of the coordinated clauses. These nonlocal comparisons argue against approaches based on local rules that treat CCE structures as special cases of clausal coordination. We advocate an alternative approach where CCE rules take the form of postediting rules applicable to nonelliptical structures. The advantage is not only a higher level of modularity but also applicability to languages belonging to different language families. We describe a language-neutral module (called Elleipo; implemented in JAVA) that generates as output all major CCE versions of coordinated clauses. Elleipo takes as input linearly ordered nonelliptical coordinated clauses annotated with lexical identity and coreferentiality relationships between words and word groups in the conjuncts. We demonstrate the feasibility of a single set of postediting rules that attains multilingual coverage.