Noam Chomsky, a linguist and cognitive scientist, introduced the concepts of "deep structure" and "surface structure" in his theory of transformational-generative grammar.
1. Deep Structure refers to the underlying, abstract representation of a sentence that contains its basic syntactic meaning. It represents the core semantic relationships between elements in a sentence.
2. Surface Structure refers to the actual form of a sentence as it is spoken or written. It is the final, transformed version of the sentence that can be derived from the deep structure through syntactic transformations (e.g., questions, negations).
Chomsky proposed that sentences with different surface structures could share the same deep structure, meaning they have the same underlying meaning but differ in how they are expressed. For example:
Deep Structure: "John is eating an apple."
Surface Structure 1: "Is John eating an apple?"
Surface Structure 2: "An apple is being eaten by John."
