CHOMSKY CLASSIFICATION OF LANGUAGES • In the definition of a grammar are the sets of symbols and So if we want to classify grammars. • We have to do it only by considering the form of productions. • Chomsky classified the grammars into four types in terms of productions (types 0 -3). • A type 0 grammar is any phrase structure grammar without any restrictions. • (All the grammars we have considered are type 0 grammars. )
LANGUAGES AND THEIR RELATION • In this section we discuss the relation between the classes of languages that we have defined under the Chomsky classification.
• Some Definitions: • Any set represented by regular expression is called Regular Set. • The class of Regular sets over ∑ is Regular Language over the terminal set ∑. • Grammar for Regular Expression is Regular Grammar.
• Converting Regular Expression to Regular Grammar: • Then we construct Grammar as : - Example 1 : -
• Converting Regular Grammar to Regular Expression and Transition System: - Then we construct a transition system : -
Example : -
• Example:
Linear grammars The Linear Grammars are either left or right: Right Linear Grammars: Rules of the forms A→ε A→a A → a. B A, B: variables and a: terminal Left Linear Grammars: Rules of the forms A→ε A→a A → Ba A, B: variables and a: terminal