| x |
| xy+x+1 |
| xy |
| xyz+xy+x |
| z |
| zx+z+1 |
=
| x |
| xy+x+1 |
| xy |
| 1+xy+x |
| zxy |
| zx•xy+zxy+xy |
=
| x |
| xy+x+1 |
| xy |
| xy+x+1 |
| 1 |
| xy+x+1 |
=
| xy+x+1 |
| xy+x+1 |
=1．
| x |
| xy+x+1 |
| y |
| yz+y+1 |
| z |
| zx+z+1 |
| x |
| xy+x+1 |
| xy |
| xyz+xy+x |
| z |
| zx+z+1 |
| x |
| xy+x+1 |
| xy |
| 1+xy+x |
| zxy |
| zx•xy+zxy+xy |
| x |
| xy+x+1 |
| xy |
| xy+x+1 |
| 1 |
| xy+x+1 |
| xy+x+1 |
| xy+x+1 |