Question

given ∑ = {a,b}:

1. describe in English the languages denoted by the regular expression: (a+b)*b(a+b)*

2. Write a regular expression: L(w) = {w | w has exactly a single substring abaa or exactly a single substring babb}

3. Write a regular expression for the following language: L(w) = {w | w ends in bb and does contain the substring aba}

Answer 1

a) L(w) = {w | w has atleast one b}

b) b*aa*baaa*b*+a*bb*abbb*a*

c)(a+b)*aba(a+b)*bb