1. 9.7: Chomsky Hierarchy

2. Turing Machine

3. Turing Machine (II) Unrestricted grammar Recognized by Turing machine
It consists of a read-write head that can be positioned anywhere along an infinite tape.
It is not a useful class of language for compiler design.

4. Linear-Bounded Automata

5. Linear-Bounded Automata
Context-sensitive
Restrictions
Left-hand of each production must have at least one nonterminal in it
Right-hand side must not have fewer symbols than the left
There can be no empty productions (N)

6. Push-Down Automata

7. Push-Down Automata (II)
Context-free
Recognized by push-down automata
Can only read its input tape but has a stack that can grow to arbitrary depth where it can save information
An automation with a read-only tape and two independent stacks is equivalent to a Turing machine.
It allows at most a single nonterminal (and no terminal) on the left-hand side of each production.

8. Finite-State Automata

9. Finite State Automata (II)
Regular language
Anything that must be remembered about the context of a symbol on the input tape must be preserved in the state of the machine.
It allows only one symbol (a nonterminal) on the left-hand, and only one or two symbols on the right.