Give Regular expressions for the following on
Σ = {a b , , c}
(a) all strings containing exactly one a
(b) all strings containing no more than three a's
(c) all strings which contain at least one occurrence of each symbol in Σ.
(d) all strings which contain no runs of a's of length greater than two.
(e) all strings in which all runs of a's have lengths that are multiples of three.