Question

Give a regular expression for each of the following languages.

e. {axb | x∈{a, b}*}

f. {(ab)n​ ​}

g. {x ∈ {a, b}* | x contains at least three consecutive as}

h. {x ∈ {a, b}* | the substring bab occurs somewhere in x}

i. {x ∈ {a, b}* | x starts with at least three consecutive as}

Answer 1

e)answer)

regular expression is a(a+b)*b

f)answer)

regular expression is (ab)* where n start from 0

g)answer)

regular expression is (a+b)*aaaa*(a+b)*

h)answer)

regular expression is (a+b)*bab(a+b)*

i)answer)

regular expression is aaaa*(a+b)*

Answer 2

e)answer)

regular expression is a(a+b)*b

f)answer)

regular expression is (ab)* where n start from 0

g)answer)

regular expression is (a+b)*aaaa*(a+b)*

h)answer)

regular expression is (a+b)*bab(a+b)*

i)answer)

regular expression is aaaa*(a+b)*