For a given context-sensitive grammar G we construct ET0L grammars G1 and G2 that are structurally equivalent if and only if the language generated by G is empty, which implies that structural equivalence is undecidable for ET0L grammars. This is in contrast to the decidability result for the E0L case. In fact, we show that structural equivalence is undecidable for propagating ET0L grammars even when the number of tables is restricted to be at most two. A stronger notion of equivalence that… Expand

We show that the EOL structural equivalence problem is logspace hard for deterministic exponential time. Also, we show that this question can be solved in linear space by a synchronized alternating… Expand

A normal form for structurally equivalent E0L grammars is constructed. Two E0L grammars are structurally equivalent iff the respective normal form grammars are isomorphic. This result gives also a… Expand

It is established that some simplification results for E0L grammars that preserve their structure are sufficient to solve the structural equivalence problem, but this does not hold in the context-free case.Expand

This chapter discusses models for Finite Automata Regular Expressions Context-Free Grammars Pushdown Automata Turing Machines Functions, Relations, and Translations, and properties of these models.Expand

A survey of the different areas of the theory of developmental systems and languages in such a way that it discusses typical results obtained in each particular problem area.Expand