As per Morris Mano
In Dual of a function We change 0 to 1 and 1 to 0 replace every AND by Or and Every Or by AND
In compliment of a function We change 0 to 1 and 1 to 0 replace every AND by Or and Every Or by And and also compliment each literal.
An dual of a function can be that function itself such functions are Know as self dual function but on other hand self complementing function does not exist.
Dual of 0 is 1, Compliment of 0 is 1
Dual of AB is A+B, Compliment of AB is (~A+~B)
let F(A,B,C)= AB+BC+CA Dual of this is the function itself. i.e Dual of F(A,B,C)=AB+BC+CA.