Chomsky [Chomsky, N. 1964. Current issues in Linguistic Theory, The Hague, Mouton] proposed a universal principle termed the “A-over-A principle,” which states that if a major category, such as NP, is directly dominated by the same major category, then any rule that would normally apply to the lower category node could apply only to the higher node. Although the principle as there formulated has not been widely accepted […] similar phenomena have been observed in a number of languages, and something resembling such a principle must still be regarded as a likely formal universal.
- Bickerton (1981), a pag.36