# 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*)

## 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.

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

## 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.
Prof.Fazal Rehman Shamil (Available for Professional Discussions)
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