PolyOrth: Orthography, phonology and morphology in inheritance lexicons

The relationship between orthography, phonology and morphology varies with different languages and writing systems. These relationships are by no means random. They follow rules, albeit with exceptions, even for relatively irregular languages like English. In this paper, we present the PolyOrth approach to representing these relationships, which definines orthographic forms in terms of their phonological and morphological correspondences within inheritance lexicons. The approach involves defining Finite State Transducers (FSTs), but in a much more subtle way than traditional speech-to-text or text-to-speech transducers. We define FSTs to provide phoneme to grapheme mappings for onsets, peaks and codas, as well as a grapheme to grapheme FST which defines spelling rules. We demonstrate the approach applied to English, Dutch and German. These three languages are interesting because they share many features of all three levels (orthography, morphology and phonology) whilst also demonstrating significant differences. This allows us to illustrate not only a range of different orthography/ phonology/ morphology relationships within languages but also the possibility of sharing information about such mappings across languages.