A General Computational Model for Word-Form Recognition and Production

A language independent model for recognition and production of word forms is presented. This "two-level model" is based on a new way of describing morphological alternations. All rules describing the morphophonological variations are parallel and relatively independent of each other. Individual rules are implemented as finite state automata, as in an earlier model due to Martin Kay and Ron Kaplan. The two-level model has been implemented as an operational computer programs in several places. A number of operational two-level descriptions have been written or are in progress (Finnish, English, Japanese, Rumanian, French, Swedish, Old Church Slavonic, Greek, Lappish, Arabic, Icelandic). The model is bidirectional and it is capable of both analyzing and synthesizing word-forms. I. Generative phonology The formalism of generative phonology has been widely used since its introduction in the 1960's. The morphology of any language may be described with the formalism by constructing a set of rewriting rules. The rules start from an underlying lexical representation, and transform it step by step until the surface representation is reached. The generative formalism is unidirectional and it has proven to be computationally difficult, and therefore it has found little use in practical morphological programs. 2. The model of Kay and Kaplan Martin Kay and Ron Kaplan from Xerox PARC noticed that each of the generative rewriting rules can be represented by a finite state automaton (or transducer) (Kay 1982). Such an automaton would compare two successive levels of the generative framework: the level immediately The work described in this paper is a part of the project 593 sponsored by the Academy of Finland. before application of the rule, and the level after application of the rule. The whole morphological grammar would then be a cascade of such levels and automata: lexical representation IFSA II t after ist rule