X2MORF: A Morphological Component Based on Augmented Two-Level Morphology

Abstract

In this paper I describe X2MORF, a language-independent morphological component for the recognition and generation of word forms based on a lexicon of morphs. The approach is an extension of two-level morphology. The extensions are motivated by linguistic examples which call into question an underlying assumption of standard two-level morphology, namely the independence of morphophonology and morphology as exemplified by two-level rules and continuation classes. Accordingly, I propose a model which allows for interaction between the two parts. Instead of using continuation classes, word formation is described in a feature-based unification grammar. Two-level rules are provided with a morphological context in the form of feature structures. Information contained in the lexicon and the word formation grammar guides the application of two-level rules by matching the morphological context against the morphs. I present an efficient implementation of this model where rules are compiled into automata (as in the standard model) and where processing of the feature-based grammar is enhanced using an automaton derived from that grammar as a filter.