1. The Chomsky Hierarchy Significance of the grammar classification
The Chomsky Hierarchy of Grammars
Using the Chomsky Hierarchy in Proofs
Context Sensitive Grammar Construction

2. Significance of the grammar classification
Each of the four grammar classes has a simple yet powerful automaton.
A useful connection between grammars, automata, and languages.
Simple class of automaton for simple class of grammar.

3. The Chomsky Hierarchy of Grammars
Languages: r.e., CSL, CFL, RL
Grammars: Chomsky Hierarchy -- 0, 1, 2, 3
Automata: TM, LBA, PDA, FA
To prove a language is to be in certain language class, you may show the language can be generated from associated grammar class. For example, G = 2 => L = CFL,
G = 0 => A = TM

4. Context Sensitive Grammar Construction
CSL -- Context Sensitive Grammar, none of the examples is easy.
The next fifty years will see natural language processing as a dominant issue -- one of research areas of Artificial Intelligence.