## RE for ending with b and having zero or multiple pairs of aa and bb

**Regular Expression = (aa+bb)*b**

## DFA for strings ending with b and having zero or multiple pairs of aa and bb

## RE for ending with b and having zero or multiple pairs of aa but no two b’s

**Regular Expression = (aa)*b**

## DFA for strings ending with b and having zero or multiple pairs of aa but no two b’s

## RE for ending with b and having one or multiple pairs of aa

**Regular Expression = ****(aa) ^{+ }b**

## RE for ending with b and having zero or multiple pairs of aa and bb, but no pair of aa after the pair of bb

## RE for ending with b and having zero or multiple sets of aa and bb, but no pair of aa after the pair of bb

## Rule

Regular Expression (RE) for ending with b and having zero or multiple sets of aa and bb must be accepted and all other strings must be rejected by our Regular Expression.

**Regular Expression = (aa)*(bb) * b**

## DFA of strings ending with b and having zero or multiple sets of aa and bb, but no pair of aa after the pair of bb

## Accepted Strings (part of the language)

These strings are not part of the given language and must be rejected by our Regular Expression.

- 3 strings of length 01 = {b,no more strings }
- 3 strings of length 02 = { no string exist}
- 3 strings of length 03= {aab, bbb, no more strings}
- 3 strings of length 04= { no string exist}
- 3 strings of length 05 = {aabbb, aaaab,bbbbb no more strings }
- 3 strings of length 06 = { no string exist }
- 3 strings of length 07 = {aaaaaab, aabbbbb, bbbbbbb, and many more similar strings }
- 3 strings of length 08= { no string exist}
- 3 strings of length 09 = {aaaaaabbb, aaaabbbbb, aaaaaaaab, and many more similar strings }
- 3 strings of length 10= { no string exist }
- Mmany more similar strings

**Rejected Strings (not part of the language)**

These strings are part of the given language and must be accepted by our Regular Expression.

- 3 strings of length 01 = {a, no more strings}
- 3 strings of length 02 = {ab, bb, aa}
- 3 strings of length 03 = {aaa, bba, abb}
- 3 strings of length 04 = {aaab, bbbb, aabb}
- 3 strings of length 05= {abbbb, aaabb, aaaaa, and many more similar strings }
- 3 strings of length 06 = {aaaaab, aabbbb,bbbbbb, and many more similar strings }
- 3 strings of length 07 = {aaaaaaa, abbbbbb, aaaaabb, and many more similar strings }
- 3 strings of length 08 = {aaaabbbb, bbbbbbbb, aabbbbbb, and many more similar strings }
- 3 strings of length 09 = {aaabbbbbb, abbbbbbbb,aaaaabbbb, and many more similar strings }
- 3 strings of length 10 = {aaaabbbbbb,aaabbbbbbb, aabbbbbbbb, and many more similar strings }

## More Examples of Regular Expression

- Regular Expression for no 0 or many triples of 0’s and many 1 in the strings.
- RegExp for strings of one or many 11 or no 11.
- A regular expression for ending with abb
- A regular expression for all strings having 010 or 101.
- Regular expression for Even Length Strings defined over {a,b}
- Regular Expression for strings having at least one double 0 or double 1.
- Regular Expression of starting with 0 and having multiple even 1’s or no 1.
- Regular Expression for an odd number of 0’s or an odd number of 1’s in the strings.
- Regular Expression for having strings of multiple double 1’s or null.
- Regular Expression (RE) for starting with 0 and ending with 1.
- RE for ending with b and having zero or multiple sets of aa and bb.
- A regular expression of the second last symbol is 1.
- RE for starting with 1 having zero or multiple even 1’s.
- Regular Expression for multiple a’s and multiple b’s.
- RE for exactly single 1 many 0’s |exactly single a many b.
- A regular expression for strings starting with aa and ending with ba.
- A regular expression for the language of all consecutive even length a’s.
- A regular expression for the language of all odd-length strings
- A regular expression for the language of all even length strings but ends with aa.
- A regular expression for the language of an odd number of 1s.
- A regular expression for the language of even length strings starting with a and ending with b in theory of automata.
- A regular expression for the language of all even length strings but starts with a.
- A Regular Expression for the Language of all strings with an even number of 0’s or even number of 1’s.
- A regular expression for the language of all those strings end with abb.
- A regular expression for string having must 010 or 101.
- Regular expression of strings begin with 110

Regular expression of strings begin and end with 110

Regular expression of strings containing exactly three consecutive 1’s. - A Regular Expression of all strings divisible by 4.
- A Regular Expression Strings that does not contain substring 110.

## Tutorial: Regular Expression

A detailed tutorial of the regular expression is here in the link of regular expression tutorial. This page contains the practice questions of regular expressions with solutions.

**Tutorial covering the topics**

- Give a regular expression.
- Describe the strings of the regular expression.
- write a regular expression.
- create all strings from regular expression.
- Generate all strings from regular expression.
- Extract all strings from regular expression.
- Find all strings from regular expression.
- Examples of regular expression.