The principles and mechanisms that constrain the combinatorial properties of lexical items in some languages of the world have been noted in many works of recent linguistic studies. Igbo language, particularly, has been observed to be consistent with most of the principles of co-occurrence constraints found in many other languages. Some of the combinatorial restrictions that have received attention in the language include, among others, selectional restriction, inherent verb compliment, and collocation. The first-mentioned is the concern of this study. So far, discussions on this topic have always been generative, suggesting that the mechanism is rule-based. This work departs from this traditional approach. It has been argued, with sufficient illustrative back-up, in the study that the acceptable (co-occurable) verb-noun combinations in the output representations of the language are reflections of optimal satisfaction of constraint hierarchy at the input (underlying) level. The instrumentalities of the Optimality Theory are exploited in driving home this argument. The verb “zu” with various bought articles is used to illustrate how sensitive the specific forms of the verb are to the noun object they co-occur with. Data used are drawn from the Izhi dialect of the language (Igbo).
Ìgbò verbs are semantically restricted from promiscuous association with other lexical items in the phrase. In other words, every Ìgbò verb bears some inherent features which must agree with the features that inhere in the adjacent or nearby complex symbol within the same structural unit. This mechanism is dealt with in generative grammar by a principle of selectional rules which specify the restriction on the permitted combinations of lexical items within a given grammatical context.
The verb zu, meaning “buy” in Ìgbo has been observed to have variants, each of which has the referential meaning “to buy” and collocates only with certain specific lexical items. This means, therefore, that each of the variants of the Ìgbò verb zú has a different collocational range or a limited number of bought article with which it can associate (Anoka, 1983). Although, Nwankwegu (2008) focuses on collocation in Ìzhí dialect of Ìgbò language, he makes a relevant observation that Ìgbò language generally exhibits finer-grain meaning through co-occurrence constraint imposed by collocation and selectional restrictions.
In this present work, though we are not exploring the generative theoretical framework, we will uphold the generative view that there are strong semantic factors determining what verb co-occurs with certain noun object in the principle of selectional restrictions. However, we will depart from the status quo, in terms of theoretical approach. This is to say that we are discarding with the rule-based theoretical framework of the generative grammar. We will therefore adopt the constraint-based approach of the OT.
A generative account of selectional restriction of the verb zu for instance would specify in a re-write rule, the restrictions associated with the verb (and presumably other categories: N, A, P). For instance, the verb zu 1) V(zu) /v(wu)
This simple re-write rule can be specified thus:
zu[vwu/ __ +N, +concrete, +bird, +domestic].
This is to say that a buy verb zu becomes wu in co-occurrence with a noun object which must be concrete and a domestic bird – leaving fowl and duck the only co-occurable object with wu. What this mean is that the solution of the specific (“numerator”) verbs is a product of rules that change the underlying forms to surface forms.
This study explores the Optimality approach, a theoretical framework proposed by Prince and Smolensky (1991, 1993), primarily, as a model of phonology, but which, by extension, has been applied to other subfields of core...