On the Containment and Equivalence Problems for GSMs, Transducers, and Linear CFGs

We explore the boundaries between decidability and undecidability of the containment and equivalence problems for restricted classes of nondeterministic generalized sequential machines (NGSMs), nondeterministic finite transducers (NFTs), nondeterministic pushdown transducers (NPDTs), and linear context-free grammars (LCFGs). We believe that our results are the sharpest known to date concerning these devices.