I suggested that these results would follow from the assumption that a subset of English sentences interesting on quite independent grounds can be defined in such a way as to impose a stipulation to place the constructions into these various categories. Furthermore, relational information does not readily tolerate a corpus of utterance tokens upon which conformity has been defined by the paired utterance test. To provide a constituent structure for T(Z,K), the earlier discussion of deviance suffices to account for the ultimate standard that determines the accuracy of any proposed grammar. It may be, then, that the systematic use of complex symbols is, apparently, determined by the requirement that branching is not tolerated within the dominance scope of a complex symbol. Nevertheless, the appearance of parasitic gaps in domains relatively inaccessible to ordinary extraction delimits problems of phonemic and morphological analysis.
see also: WikiPedia -- Chomskybot