Deterministic Context Free Languages

A number of results about deterministic languages (languages accepted by pushdown automata with no choice of moves) are established. In particular, o (1) each deterministic language is unambiguous. (2) the complement of each deterministic language is a deterministic language. (3) numerous operations which preserve deterministic languages (for example, intersection with a regular set) are obtained. (4) several problems are shown to be recursively unsolvable.