Grammatical relations have always constituted a primary focus of attention in the study
of language. Within the last three decades, the topicality of this trend has increasingly
been determined by the quest for a universal characterization of the language faculty
which has shaped the goals and directives of most current works in theoretical linguistics.
Although the realization patterns and syntactic functionality of grammatical relations
are subject to cross-linguistic variation, studies in comparative grammar have provided
suggestive evidence that the range of variation found can often be contained within
the limits fixed by a discrete set of parameters. The investigation of these parameters
has broached the possibility of a universal specification of the nature of grammatical
relations. This thesis proposes that such a specification should be achieved by establishing
regularities in the syntax-semantics interface within a constraint-based approach
to linguistic analysis that integrates a precise computational interpretation. In keeping
with this objective, a unification-based categorial grammar framework is developed
which incorporates the semantic insights of a Neo-Davidsonian approach to verb semantics
and predicate-argument combination, where thematic roles are defined as clusters
of entailments of verb meanings. This framework is extended with an integrated approach
to argument selection and selection change. Properties of the resulting system
are demonstrated with respect to a variety of natural language phenomena concerning
grammatical function changing, unaccusativity and clitic dislocation
