Some decision problems concerning sequential transducers and checking automata

摘要

Boundary points between decidability and undecidability of various decision questions concerning two-way sequential transducers and checking automata are investigated. The results show how some unsolvable problems become solvable when certain restrictions (e.g., the machines being deterministic, reversal-bounded, etc.) are imposed. A solution to an open problem concerning cascade products of pushdown automata is also given.