Example : { 0, 11, 01, 011 } 
{ 1, 01, 110 } = { 0, 11, 01, 011, 111 }
{ 1, 01, 110 } = { 0, 11, 01, 011, 111 }
Intersection : A string 
iff 
and 
.
Example : { 0, 11, 01, 011 } 
{ 1, 01, 110 } = { 01 }
Complement : Usually, 
is the universe that a complement is taken with respect to. Thus for a language L, the complement is L(bar) = { 
| 
}.
Example : Let L = { x | |x| is even }. Then its complement is the language { | |x| is odd }.
Similarly we can define other usual set operations on languages like relative complement, symmetric difference, etc.