u v w x
f
1
f
2
0 0 0 0
0 0
0 0 0 1
0 1
0 0 1 0
1 0
0 0 1 1
? ?
0 1 0 0
0 1
0 1 0 1
1 0
0 1 1 0
0 0
0 1 1 1
? ?
1 0 0 0
0 0
1 0 0 1
0 0
1 0 1 0
1 1
1 0 1 1
? ?
1 1 0 0
? ?
1 1 0 1
? ?
1 1 1 0
? ?
1 1 1 1
? ?
Exercise: Òread offÓ the
expression for f
2
.