Step |
Hyp |
Ref |
Expression |
1 |
|
imassrn |
|- ( `' F " B ) C_ ran `' F |
2 |
|
dfdm4 |
|- dom F = ran `' F |
3 |
|
fdm |
|- ( F : A --> B -> dom F = A ) |
4 |
|
ssid |
|- A C_ A |
5 |
3 4
|
eqsstrdi |
|- ( F : A --> B -> dom F C_ A ) |
6 |
2 5
|
eqsstrrid |
|- ( F : A --> B -> ran `' F C_ A ) |
7 |
1 6
|
sstrid |
|- ( F : A --> B -> ( `' F " B ) C_ A ) |
8 |
|
fimass |
|- ( F : A --> B -> ( F " A ) C_ B ) |
9 |
|
ffun |
|- ( F : A --> B -> Fun F ) |
10 |
4 3
|
sseqtrrid |
|- ( F : A --> B -> A C_ dom F ) |
11 |
|
funimass3 |
|- ( ( Fun F /\ A C_ dom F ) -> ( ( F " A ) C_ B <-> A C_ ( `' F " B ) ) ) |
12 |
9 10 11
|
syl2anc |
|- ( F : A --> B -> ( ( F " A ) C_ B <-> A C_ ( `' F " B ) ) ) |
13 |
8 12
|
mpbid |
|- ( F : A --> B -> A C_ ( `' F " B ) ) |
14 |
7 13
|
eqssd |
|- ( F : A --> B -> ( `' F " B ) = A ) |