| Step |
Hyp |
Ref |
Expression |
| 1 |
|
str.1 |
|
| 2 |
|
str.2 |
|
| 3 |
|
dfral2 |
|
| 4 |
1 2
|
strlem1 |
|
| 5 |
|
eqid |
|
| 6 |
|
biid |
|
| 7 |
5 6 1 2
|
strlem3 |
|
| 8 |
5 6 1 2
|
strlem6 |
|
| 9 |
|
fveq1 |
|
| 10 |
9
|
eqeq1d |
|
| 11 |
|
fveq1 |
|
| 12 |
11
|
eqeq1d |
|
| 13 |
10 12
|
imbi12d |
|
| 14 |
13
|
notbid |
|
| 15 |
14
|
rspcev |
|
| 16 |
7 8 15
|
syl2anc |
|
| 17 |
16
|
rexlimiva |
|
| 18 |
4 17
|
syl |
|
| 19 |
18
|
con1i |
|
| 20 |
3 19
|
sylbi |
|