Early versions of Chomsky's theory were called transformational grammar, and this term is still used as a general term that includes his subsequent theories. There are a number of competing versions of generative grammar currently practiced within linguistics. Chomsky's current theory is known as the Minimalist program. Other prominent theories include or have included dependency grammar, head-driven phrase structure grammar, lexical functional grammar, categorial grammar, relational grammar, link grammar, and tree-adjoining grammar.[citation needed]
Chomsky has argued that many of the properties of a generative grammar arise from an "innate" universal grammar. Proponents of generative grammar have argued that most grammar is not the result of communicative function and is not simply learned from the environment (see poverty of the stimulus argument). In this respect, generative grammar takes a point of view different from cognitive grammar, functional, and behaviorist theories.[citation needed]
Most versions of generative grammar characterize sentences as either grammatically correct (also known as well formed) or not. The rules of a generative grammar typically function as an algorithm to predict grammaticality as a discrete (yes-or-no) result. In this respect, it differs from stochastic grammar, which considers