{a}

{ ∈ , a, b }

{a, b}

{ ab }

{ a, b, ab, aa }

{ a, b, ba, bb }

{ a, b }

{ aa, ab, ba, bb }

a | b

(ab)*

(a | b)*

a*| b

(0 | 1) *

(0 | 1) (0 | 1)*

(00 01 1 10)*

(0 | 1 ) (0 | 1)(0 | 1) *

with zero or more instances of a or b

with one or more instances of a or b

equal to regular expression (a* b*)*

both 1) with zero or more instances of a or b and 2) equal to regular expression (a* b*)*