A scale of context sensitive languages: Applications to natural language

The classes of languages Ti are defined, i being a natural number, for which it is proved that Ti is a proper subset of T i+1, and a proper subset of context-sensitive languages, if Ti is the set of all context-free languages and Ti+1 is the set of all possible translations from Ti by means of a so-called linear deterministic pushdown store transducer; the formal mechanism is close enough to the so-called functional generative description, which has already been applied to large subsets of natural languages