On some decision questions concerning pushdown machines

Oscar H. Ibarra
1983 Theoretical Computer Science  
Certain decision questions (e.g., equivalence, ambiguity, single-valuedrtcss, monotonicity, etc.) concerning pushdown transducers and acceptors are investigated. Exampfes of results shown are the following: (1) There is an aIgorithm to decide given two deterministic pushdown transducers, one of which has a 'finite-turn' counter for a pushdown stack, whether they are ~~ui~a~ent [i.e., they define the same input/output relation). (2) There are subclasses of pushdown acceptors which have a
more » ... e ambiguity pro&i3 but an undecidable inherent ambiguity problem. (It seems that these classes are the first known to exhibit this property.) (3) There is an algorithm to decide given a homomorphism h and a language L accepted bv a finite-turn nondeterministic counter automaton whet)rpr h is one-to-one on L. In Contras!, there is RO such algorithm if L is accepted by a 1 -turn deterministic pushdown automaton or hy an unrestricted deterministic counter automaton.
doi:10.1016/0304-3975(83)90006-3 fatcat:6pi7tunh75dsrdix4rs6qaqsk4