Lexicase parsing

Abstract

This paper presents a lexicon-based approach to syntactic analysis, Lexicase, and applies it to a lexicon-driven computational parsing system. The basic descriptive mechanism in a Lexicase grammar is lexical features. The properties of lexical items are represented by contextual and non-contextual features, and generalizations are expressed as relationships among sets of these features and among sets of lexical entries. Syntactic tree structures are representaed as notworks of pairwise dependency relationships among the words in a sentence. Possible dependencies are marked as contextual features on individual lexical items, and Lexicase parsing is a process of picking out words in a string and attaching dependents to them in accordance with their contextual features. Lexicase is an appropriate vehicle for parsing because Lexicase analyses are monostratal, flat, and relatively non-abstract, and it is well suited to machine translation because grammatical representations for corresponding sentences in two languages will be very similar to each other in structure and inter-constituent relations, and thus far easier to interconvert.