This paper investigates the subcategorization and structure of dayue, taking a Lexical Functional Grammar–Optimality Theory (LFG-OT) approach to account for the different uses of this word. It argues that dayue can be identified in the category of either an adverb or a preposition, depending on the function it takes and the structure it has. As an adverb, dayue modifies the clausal element or the quantifier phrase directly following it. As a preposition, dayue takes a noun phrase (NP) or an adpositional phrase as the complement, occurring in the adjunctive position. There may be ambiguities due to the subcategorization of, and the argument structure associated with, dayue, which result in the same linguistic form being generated as optimal outputs for different input meanings. However, each can be argued to correspond to a different c-structure. An LFG-OT approach is adopted in this paper to account for the structure of dayue. LFG proposes different levels of representation, and OT is involved in the theoretical model by evaluating linguistic forms according to the interaction and ranking of different kinds of linguistic constraints. Faithfulness constraints ensure faithful mappings among the lexical, functional, and syntactic levels of representation. Markedness constraints require linguistic structures to be well formed. Economy constraints pursue a concise, efficient way of expression. Alignment constraints map arguments with constituent structures.
