Ga imperatives and richness of the base

Abstract

This paper proposes a solution to a Richness of the Base problem that is inherent in the morpho-tonology of Gã verbs to which the imperative morpheme i.e. a floating high tone (plus sometimes, a segmental -m´) suffix is attached. Generally, this morphophonological process suggests that there is an asymmetry between surface low toned monosyllabic stems but not bisyllabic stems, in the language. A rule-based account by Paster (2000) leads to a verb inventory that excludes the existence of underlying low-toned bisyllabic verb stems in Gã contra earlier observations e.g. Wentum (1997). However given the Richness of the Base hypothesis in Optimality Theory, this is a problem. I argue and show that the missing bisyllabic verb stem contrast can be derived via a constraint ranking schema which forces both underlyingly low-toned and toneless bisyllabic stems to behave in a similar manner on the surface although it preserves the contrast in monosyllablic stems of similar tonal shapes