Answer and Step-by-step explanation:
a. The strings {a, b, c} with at least one a and at least one b.
Solution: ∑ = {a, b, c}
where
(a +b +c)(a (a +b +c)*b + b (a +b +c) a (a +b +c)*
b. The set of 0’s and 1’s string whose tenth symbol from the right end is 1.
Sol: (0+1)*1(0+1)9
c. The set of 0’s and 1’s string with at most one pair of consecutive 1’s.
sol: (0+10)(11+∑)(0+10)
