The document discusses Noam Chomsky's early work developing transformational grammar. It explains that phrase structure rules break sentences down into constituent parts like noun phrases and verb phrases. Chomsky used these rules to generate the nonsense sentence "Colorless green ideas sleep furiously" to show they can create syntactically correct but semantically incorrect sentences. It then discusses how transformational grammar introduced the concepts of deep structure and surface structure, with deep structure representing core semantic relations and surface structure following phonological form, connected by transformations. Generative grammar aims to predict which word combinations form grammatical sentences.