Operator (linguistics)
In generative grammar, the technical term operator denotes a type of expression that enters into an a-bar movement dependency.[5] It is also common within generative grammar to hypothesise phonetically empty operators whenever a clause type or construction exhibits symptoms of the presence of an a-bar movement dependency, such as sensitivity to extraction islands.In the generative model of the syntax-semantics interface, a quantifier must move to positions higher in the structure, leaving behind a trace which it then binds.Part of the reason to assume the empty operator—variable dependency in such sentences is that they exhibit sensitivity to extraction islands.This means that the operator Opx is unable to bind its variable "x", and this is thought to be the reason why the sentence is ungrammatical.