Consider the logic circuit as shown in the figure below, the function f1, f2 and f (in canonical sum of products form in decimal notation) are
f1(w, x, y, x ) = ∑ (8, 9, 10)
f2 (w, x, y, x ) = ∑ (7, 8, 12, 13, 14, 15)
f(w, x, y, x ) = ∑ (8, 9)
The function f3 is
1
∑ (9, 10)
2
∑ (9)
3
∑ (1, 8, 9)
4
∑ (8, 10, 18)