deep structure

n. Deep structure is the underlying hierarchical structure for a sentence generated by phrase structure rules. It is a level of representation proposed in early versions of generative grammar, set up to account for the fact that sentences with different surface forms are nonetheless syntactically related. For example, in the sentences The cop arrested the thug and The thug was arrested by the cop, the main verb of the sentence, arrest, has the same agent, cop, and the same patient, thug, even though these two nouns occupy different structural positions. The phrase structure rules that generate deep structure are rules that expand sentence constituents. For example, a sentence (S) has two obligatory major constituents: a subject noun phrase (NP) and a predicate verb phrase. The rule generating this structure might be formulated as S → NP VP.

- EMF