Minterm: A product term which contains each of 'n' variable as factors either in complemented or uncomplemented form is called minterm. For ex: 3 variable function abcc is a minterm but not ab (as this product term doesn't contains all the 3 term).
Canonical Sum of Products: The Sum of all minterms of function 'f' for which 'f' assumes '1' is called Canonical sum of products or disjunctive normal form.
Maxterm: A sum term which contains each of 'n' variable as factors either in complemented or uncomplemented form is called minterm. For ex: 3 variable function (a + bc + c) is a maxterm but not (a + b).
Canonical Product of Sums: The product of all maxterms of function 'f' for which 'f' assumes '0' is called Canonical product of sums or conjunctive normal form.
Neutral Function: Neutral function are the function having no. of minterm in Canonical SOP is equal to no. of maxterm in Canonical POS.
Self dual function: If the dual of a function is equal to the function. Then the function is called self dual. A dual function is obtained by interchanging every '.' and '+'.
A Boolean function is self dual function if
1. It is neutral function.
2. The function does not contain mutually exclusive terms.
More ever, The Canonical sum of products or Product of sums of a Switching function is unique. Means for a function you will have only one Canonical SOP.
These definition may not be standard. But these are what i have learned. So if anyone is wrong correct it.