" f(x',y,z')=f(x,y,z) " It says for the function value of x',y,z' and x,y,z will be same.
suppose x',y,z' = (1,0,1) then x,y,z = (0,0,0) i,e function value at f(1,0,1) = f(0,0,0) = either 0 or 1.. Lets make all such pairs
x |
y |
z |
f |
0
1 |
0
0 |
0
1 |
2 possible value i.e either 0 or 1 |
0
1 |
0
0 |
1
0 |
2 possible value i.e either 0 or 1 |
0
1 |
1
1 |
0
1 |
2 possible value i.e either 0 or 1 |
0
1 |
1
1 |
1
0 |
2 possible value i.e either 0 or 1 |
so maximum number of boolean expression that can be form = 2 x 2 x 2 x 2 = 16