possibilities specified in their syntactic categories. For example, other approaches might posit a rule that combines a noun phrase (NP) and a verb phrase (VP), but CG would posit a syntactic category NP and another NP\S, read as "a category that searches to the left (indicated by \) for an NP (the element on the left) and outputs a sentence (the element on the right)." Thus, the syntactic category for an intransitive verb is a complex formula representing the fact that the verb acts as a function word requiring an NP as an input and produces a sentence level structure as an output. The complex category is notated as (NP\S) instead of V. The category of transitive verb is defined as an element that requires two NPs (its subject and its direct object) to form a sentence. That is notated as (NP/(NP\S)), which means, "A category that searches to the right (indicated by /) for an NP (the object) and generates a function (equivalent to the VP) which is (NP\S), which in turn represents a function that searches to the left for an NP and produces a sentence." Tree-adjoining grammar is a categorial grammar that adds in partial tree structures to the categories. Stochastic/probabilistic grammars/network theories Theoretical approaches to syntax that are based upon probability theory are known as stochastic grammars. One common implementation of such an approach makes use of a neural network or connectionism. Functional grammars Functionalist models of grammar study the form–function interaction by performing a structural and a functional analysis. Functional discourse grammar (Dik) Prague linguistic circle Role and reference grammar (RRG) Systemic functional grammar Generative syntax Generative syntax is the study of syntax within the overarching framework of generative grammar. Generative theories of syntax typically propose analyses of grammatical patterns using formal tools such as phrase structure grammars augmented with additional operations such as syntactic movement. Their goal in analyzing a particular language is to specify rules which generate all and only the expressions which are well-formed in that language. In doing so, they seek to identify innate domain-specific principles of linguistic cognition, in line with the wider goals of the generative enterprise. Generative syntax is among the approaches that adopt the principle of the autonomy of syntax by assuming that meaning and communicative intent is determined by the syntax, rather than the other way around. Generative syntax was proposed in the late 1950s by