Step |
Hyp |
Ref |
Expression |
1 |
|
dff13 |
|
2 |
|
fveq2 |
|
3 |
|
df-ov |
|
4 |
2 3
|
eqtr4di |
|
5 |
4
|
eqeq1d |
|
6 |
|
eqeq1 |
|
7 |
5 6
|
imbi12d |
|
8 |
7
|
ralbidv |
|
9 |
8
|
ralxp |
|
10 |
|
fveq2 |
|
11 |
|
df-ov |
|
12 |
10 11
|
eqtr4di |
|
13 |
12
|
eqeq2d |
|
14 |
|
eqeq2 |
|
15 |
|
vex |
|
16 |
|
vex |
|
17 |
15 16
|
opth |
|
18 |
14 17
|
bitrdi |
|
19 |
13 18
|
imbi12d |
|
20 |
19
|
ralxp |
|
21 |
20
|
2ralbii |
|
22 |
9 21
|
bitri |
|
23 |
22
|
anbi2i |
|
24 |
1 23
|
bitri |
|