Step |
Hyp |
Ref |
Expression |
1 |
|
dfcleq |
|
2 |
|
df-in |
|
3 |
2
|
eqeq1i |
|
4 |
|
df-ss |
|
5 |
|
simp2 |
|
6 |
5
|
3expib |
|
7 |
|
ancl |
|
8 |
6 7
|
impbid |
|
9 |
|
dfbi2 |
|
10 |
|
pm2.21 |
|
11 |
|
pm3.4 |
|
12 |
10 11
|
ja |
|
13 |
9 12
|
simplbiim |
|
14 |
8 13
|
impbii |
|
15 |
|
df-clab |
|
16 |
|
eleq1w |
|
17 |
|
eleq1w |
|
18 |
16 17
|
anbi12d |
|
19 |
18
|
sbievw |
|
20 |
15 19
|
bitr2i |
|
21 |
20
|
bibi1i |
|
22 |
14 21
|
bitri |
|
23 |
22
|
albii |
|
24 |
4 23
|
bitri |
|
25 |
1 3 24
|
3bitr4ri |
|