In this tutorial we will discuss how to decide whether a perticular grammar/langauge is regular or not.

So follow given steps:

- Every finite language is regular that means if there is a limit to the language then it is regular.

For example the language, L = { a^{20}b^{20}} is regular langauge whereas,

Langauge, L = { a^{n}b^{n}| n > 0} is not regular. - Second case is if there is an infinite languge then we will check whether its DFA can be created. If no then it will not be a regular language

And also we must have a pattern in the language otherwise FA cannot be created.

**Example**

Suppose given language, L = {ab, abab, ababab, ....}

As we can see that there is a pattern in the language that is (ab)^{n}

So we can create FA for it as follows

Cleary it is NFA so we are good to say that the language given is a regular language.

- String length should be in arithmetic progression

*Rest of things will get clear using examples in next pages*