DeMol’gan’s Theorems:
a. (A + B) = A* B
b. A*B = A + B
Proof of DeMorgan’s Theorem (b):
For any theorem X = Y, if we can show that X Y = 0, and that X + Y = 1, then by the complement postulates, A A = 0 and A + A = 1, X = Y. By the uniqueness of the complement, X = Y. Thus the proof consists of showing that (A*B)*( A + B) = 0; and also that (A*B) + ( A + B) = 1.
