Step |
Hyp |
Ref |
Expression |
1 |
|
brttrcl |
|
2 |
|
df-1o |
|
3 |
2
|
difeq2i |
|
4 |
3
|
eleq2i |
|
5 |
|
peano1 |
|
6 |
|
eldifsucnn |
|
7 |
5 6
|
ax-mp |
|
8 |
|
dif0 |
|
9 |
8
|
rexeqi |
|
10 |
4 7 9
|
3bitri |
|
11 |
10
|
anbi1i |
|
12 |
|
r19.41v |
|
13 |
11 12
|
bitr4i |
|
14 |
13
|
exbii |
|
15 |
|
df-rex |
|
16 |
|
rexcom4 |
|
17 |
14 15 16
|
3bitr4i |
|
18 |
|
vex |
|
19 |
18
|
sucex |
|
20 |
|
suceq |
|
21 |
20
|
fneq2d |
|
22 |
|
fveqeq2 |
|
23 |
22
|
anbi2d |
|
24 |
|
raleq |
|
25 |
21 23 24
|
3anbi123d |
|
26 |
25
|
exbidv |
|
27 |
19 26
|
ceqsexv |
|
28 |
27
|
rexbii |
|
29 |
1 17 28
|
3bitri |
|