Robert Van Valin is the principal writer behind Functional Linguistics, which is an offshoot of the cognitive linguistics field pioneered by Langacker. His 1997 monograph 'Syntax: structure, meaning and function' is an attempt to provide a method for syntactic analysis which is just as relevant for languages like Dyirbal and Lakhota as it is for more commonly studied Indo-European languages. Instead of positing a separate layer of deep structure to explain departures from Chomsky's canonical word order, Van Valin suggests that the only truly universal parts of a sentence are its nucleus, generally a predicating element such as a verb or adjective, and the arguments, normally noun phrases, that the nucleus requires. Van Valin also departs from Chomskyan syntactic theory by denying the existence of the verb phrase.