| Step |
Hyp |
Ref |
Expression |
| 1 |
|
f1owe.1 |
|- R = { <. x , y >. | ( F ` x ) S ( F ` y ) } |
| 2 |
|
f1f |
|- ( F : A -1-1-> B -> F : A --> B ) |
| 3 |
|
frn |
|- ( F : A --> B -> ran F C_ B ) |
| 4 |
|
wess |
|- ( ran F C_ B -> ( S We B -> S We ran F ) ) |
| 5 |
2 3 4
|
3syl |
|- ( F : A -1-1-> B -> ( S We B -> S We ran F ) ) |
| 6 |
|
f1f1orn |
|- ( F : A -1-1-> B -> F : A -1-1-onto-> ran F ) |
| 7 |
1
|
f1owe |
|- ( F : A -1-1-onto-> ran F -> ( R We A <-> S We ran F ) ) |
| 8 |
6 7
|
syl |
|- ( F : A -1-1-> B -> ( R We A <-> S We ran F ) ) |
| 9 |
5 8
|
sylibrd |
|- ( F : A -1-1-> B -> ( S We B -> R We A ) ) |