Case and person in the direct-inverse agreement system of Yimas

Verbal agreement systems for the person/number of core arguments are often divided into types, two of which are systems in which indexing is case governed versus those in which it is person governed. But in languages like Yimas, constraints of both types of systems are present. All core arguments are signaled only by verbal indexing. These are indicated by an elaborate system of pronominal affixes aligned essentially according to a split ergative pattern: local persons, first and second, in a three way split, ERG-NOM-ACC, and the non-local third person in a different three way split, ERG-NOM-DAT. The realization of these cases is not straightforwardly linked to the core grammatical relations, as the expression of a person-based direct-inverse system is layered on top of the case marking system. This paper presents a formal Optimality Theory based analysis of Yimas verb indexing.