# RE for exactly single 1 many 0’s |exactly single a many b

## RE for exactly single 1 many 0’s

Let us see the RE for exactly single 1 and many 0’s defined over {0,1).

## Rule**: **

All strings having exactly single 1 and many 0’s must be accepted and all strings that don’t have exactly single 1 must be rejected by our Regular Expression.

RE = (0*10*)

## FA (DFA) for exactly single 1 many 0’s

## Rejectable strings (not 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 1 = {0, no more string}
- 3 strings of length 2 = {11, 00, no more string}
- 3 strings of length 3= {011,101,110, and many more similar strings}
- 3 strings of length 4 = {1010, 0101, 0011, and many more similar strings }
- 3 strings of length 7 = {1000010, 0010001, 0001100, and many more similar strings }
- 3 strings of length 10 = {0000100001, 1100000001, 1000000001, and many more similar strings }
- 3 strings of length 15 = {000001000000011, 110001000000000, 100000000000011, and many more similar strings }
- 3 strings of length 20 = {10000001000000000000, 00000000001000001001, 11000000001000000000, and many more similar strings }
- 3 strings of length 25 = {0000000000100000000010000, 1000000000000001000000000, 1100000000100000000010000, and many more similar strings }

## Acceptable strings (part of the language):

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

- 3 strings of length 1 = {1, no more string}
- 3 strings of length 2 = {01, 10, no more string}
- 3 strings of length 3= {010,001,100, no more string }
- 4 strings of length 4 = {0010, 0100, 1000, 0001, no more string}
- 3 strings of length 7 = {0001000, 0000100, 0010000, and many more similar strings }
- 3 strings of length 10 = {0000010000, 0001000000, 0100000000, and many more similar strings}
- 3 strings of length 15 = {000001000000000, 000000000010000, 000000100000000, and many more similar strings }
- 3 strings of length 20 = {00000000001000000000, 00000100000000000000, 00100000000000000000, and many more similar strings }
- 3 strings of length 25 = {0000000000100000000000000, 0000010000000000000000000, 0000000100000000000000000, and many more similar strings }

# Regular Expression (RE) for exactly single b and many a’s

Let us see the Regular Expression (RE) for exactly single b and many a’s in the string.

## Rule:

All strings having exactly single b and many a’s must be accepted and all strings that don’t have exactly single b must be rejected by our Regular Expression.

RE = (a*ba*)

## Rejectable strings (not 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 1 = {a, no more string}
- 3 strings of length 2 = {bb, aa, no more string}
- 3 strings of length 3= {abb,bab,bba, and many more similar strings}
- 3 strings of length 4 = {baba, abab, aabb, and many more similar strings }
- 3 strings of length 7 = {baaaaba, aabaaab, aaabbaa, and many more similar strings }
- 3 strings of length 10 = {aaaabaaaab, bbaaaaaaab, baaaaaaaab, and many more similar strings }
- 3 strings of length 15 = {aaaaabaaaaaaabb, bbaaabaaaaaaaaa, baaaaaaaaaaaabb, and many more similar strings }
- 3 strings of length 20 = {baaaaaabaaaaaaaaaaaa, aaaaaaaaaabaaaaabaab, bbaaaaaaaabaaaaaaaaa, and many more similar strings }
- 3 strings of length 25 = {aaaaaaaaaabaaaaaaaaabaaaa, baaaaaaaaaaaaaabaaaaaaaaa, bbaaaaaaaabaaaaaaaaabaaaa, and many more similar strings }
- Many more similar strings.

## Acceptable strings (part of the language):

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

- 3 strings of length 1 = {b, no more string}
- 3 strings of length 2 = {ab, ba, no more string}
- 3 strings of length 3= {aba,aab,baa, no more string }
- 4 strings of length 4 = {aaba, abaa, baaa, aaab, no more string}
- 3 strings of length 7 = {aaabaaa, aaaabaa, aabaaaa, and many more similar strings }
- 3 strings of length 10 = {aaaaabaaaa, aaabaaaaaa, abaaaaaaaa, and many more similar strings}
- 3 strings of length 15 = {aaaaabaaaaaaaaa, aaaaaaaaaabaaaa, aaaaaabaaaaaaaa, and many more similar strings }
- 3 strings of length 20 = {aaaaaaaaaabaaaaaaaaa, aaaaabaaaaaaaaaaaaaa, aabaaaaaaaaaaaaaaaaa, and many more similar strings }
- 3 strings of length 25 = {aaaaaaaaaabaaaaaaaaaaaaaa, aaaaabaaaaaaaaaaaaaaaaaaa, aaaaaaabaaaaaaaaaaaaaaaaa, and many more similar strings }
- Many more similar strings.

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RE for exactly single 1 many 0s exactly single a many b

## 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.