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# Examples of Infinite Regular Expressions

Infinite Regular expressions are used to represent the infinite regular languages. So, the length of infinite regular expressions is always Unlimited.

## Example 01

Write the regular expression for the language which accepting all the strings which having all combinations of a’s over ∑ = {a}.

Solution

Language for given example is given below

L = { ε, a, aa, aaa, aaaa, aaaaa, ……….. }

Regular expression for above language is given below

L(R) = a*

## Example 02

Write the regular expression for the language which accepting all the strings which having all combinations of a’s except the null string over ∑ = {a}.

Solution

Language for given example is given below

L = {a, aa, aaa, aaaa, aaaaa, ……….. }

Regular expression for above language is given below

L(R) = a+

## Example 03

Write the regular expression for the language which accepting all the strings, which having any number of a’s and b’s over ∑ = {a, b}.

Solution

Language for given example is given below

L = {a, b, ab, ba, aab, aba, aaba ……….. }

Regular expression for above language is given below

L(R) = (a+b)*

## Example 04

Write the regular expression for the language which accepting all the strings, having only one “b” and any numbers of “a” over ∑ = {a, b}.

Solution

Language for given example is given below

L = {b, ab, aba, abaa, abaaaa, aaaaabaaaaaaa……….. } // all strings having only one “b”

Regular expression for above language is given below

L(R) = a*ba*

## Example 05

Write the regular expression for the language which accepting all the strings, which are starting with 1 and ending with 0, over ∑ = {0, 1}.

Solution

Language for given example is given below

L = {10, 100, 11010, 1110, 1111000, ……….. } // starting with 1 and ending with 0

Regular expression for above language is given below

L(R) = 1(0+1)*0

## Example 06

Write the regular expression for the language which accepting all the strings having even length, over ∑ = {0}.

Solution

Language for given example is given below

L = { ε, 00, 0000, 000000, 00000000, ……….. }

Regular expression for above language is given below

L(R) = (00)*

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