.model top
.inputs cin a0 a1 a2 a3 b0 b1 b2 b3
.outputs s0 s1 s2 s3 cout
.names $false
.names $true
1
.names $undef
.names b0 a0 cin s0
001 1
010 1
100 1
111 1
.names b0 a0 cin c0
011 1
101 1
110 1
111 1
.names b1 a1 c0 s1
001 1
010 1
100 1
111 1
.names b1 a1 c0 c1
011 1
101 1
110 1
111 1
.names b2 a2 c1 s2
001 1
010 1
100 1
111 1
.names b2 a2 c1 c2
011 1
101 1
110 1
111 1
.names b3 a3 c2 s3
001 1
010 1
100 1
111 1
.names b3 a3 c2 cout
011 1
101 1
110 1
111 1
.end