Chomsky hierarchy | Grammars | Languages | Abstract machines |
---|---|---|---|
Type-0 | Unrestricted | Recursively enumerable | Turing machine |
— | (no common name) | Decidable | Decider |
Type-1 | Context-sensitive | Context-sensitive | Linear-bounded |
— | Positive range concatenation | Positive range concatenation* | PTIME Turing Machine |
— | Indexed | Indexed* | Nested stack |
— | — | — | Thread automaton |
— | Linear context-free rewriting systems | Linear context-free rewriting language | restricted Tree stack automaton |
— | Tree-adjoining | Tree-adjoining | Embedded pushdown |
Type-2 | Context-free | Context-free | Nondeterministic pushdown |
— | Deterministic context-free | Deterministic context-free | Deterministic pushdown |
— | Visibly pushdown | Visibly pushdown | Visibly pushdown |
Type-3 | Regular | Regular | Finite |
— | — | Star-free | Counter-free (with aperiodic finite monoid) |
— | Non-recursive | Finite | Acyclic finite |