Monday, April 30, 2007

Automata Step by Step

Now we also need definition of “regular grammar”

Regular Grammars:

Regular grammars describe exactly all regular languages and are in that sense equivalent to finite state automata and regular expressions. Moreover, the right regular grammars by themselves are also equivalent to the regular languages, as are the left regular grammars.

Every regular grammar is a context-free grammar. Every context-free grammar can be easily rewritten into a form in which only a combination of left regular and right regular rules is used. Therefore, such grammars can express all context-free languages. Regular grammars, which use either left-regular or right-regular rules but not both, can only express a smaller set of languages, called the regular languages. In that sense they are equivalent with finite state automata and regular expressions.

What is a regular language? It is important to understand “regular language” for better understanding of above definitions. We will discuss it in our next post..

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