Preservation of Languages by Transducers

Abstract : A linear bounded transducer (pushdown transducer) is a linear bounded automaton (pushdown automaton) with outputs. Answers to the following two problems are derived: (1) If S is a linear bounded transducer or a pushdown transducer, and L is context sensitive, context free, or regular; is S(L) some well known type of set (2) Does there exist a decision procedure to determine for arbitrary sets L sub 1 and L sub 2, both context sensitive or both context free, whether there exists a linear bounded transducer (pushdown transducer) which maps (a) L sub 1 onto L sub 2 or (b) L sub 1 into L sub 2 nontrivially. (Author)