Representing morphological tone in a computational grammar of Hausa

In this paper I shall discuss the representation of morphological tone in Hausa, as implemented in a computational grammar of the language, referred to as HaG, which has been developed within the framework of Head-driven Phrase Structure Grammar. Based on an in-depth study of segmental and suprasegmental properties manipulated by morphological processes, I shall argue that two fundamental insights from Autosegmental Phonology needs to be seamlessly integrated into typed feature structure grammars of languages with grammatical tone, namely (i) the systematic separation of tonal and metrical information from the string of consonants and vowels, and (ii) the possibility of tonal spreading, i.e. the possibility for a tonal specification to be assigned to an arbitrary number of adjacent tone-bearing units (syllables). To this end, I present a formalisation of tonal melodies in terms of typed list constraints that implement a notion of tonal spreading, allowing for an underspecified description of tonal melodies, independent of the number of tone-bearing units. I shall finally show that this minimal encoding is sufficient and flexible enough to capture the range of suprasegmental phenomena in Hausa.