Dependency is a general term that refers to different structural relations. We highlight three very general classes of phenomena that are often captured by this term: (i) the structural relation between a lexical head (e.g., V, N, A) and the functional structure projected by it such as the relation between a verb and an auxiliary or between a noun and a determiner; (ii) the local selectional relation between a lexical head and the constituents that are combined merged with it to satisfy its argument structure, as in the case of the verb and the direct and indirect objects; (iii) the structural relation created by two different constituents that share the same referential index. In the latter case, we observe two major types: a constituent is displaced, as in the case of the subject of a passive clause or a wh-constituent; or two constituents share the same referent but have different functions in the clause (or in different clauses), as is the case of pronouns and their antecedents
