Penthouse principle
The penthouse principle, a term in syntax coined by John R. Ross in 1973, describes the fact that many syntactic phenomena treat matrix clauses differently from embedded clauses:
The penthouse named in the principle is the top-floor of a highrise apartment building, and is a metaphor for the matrix clause in a multi-clause structure. Perhaps the best-known example of a penthouse principle effect is the distribution of subject-auxiliary inversion in constituent questions in English, which in many varieties of English is restricted to matrix clauses:
Compare:
Other phenomena falling under the penthouse principle are V2-effects in the Germanic languages and the distribution of declarative markers, imperative morphology, and of various particles in a variety of languages.
