Step |
Hyp |
Ref |
Expression |
1 |
|
eqidd |
|
2 |
|
inss1 |
|
3 |
2
|
a1i |
|
4 |
|
elssuni |
|
5 |
4
|
adantl |
|
6 |
3 5
|
sstrd |
|
7 |
|
dfss4 |
|
8 |
6 7
|
sylib |
|
9 |
8
|
eqcomd |
|
10 |
9
|
3adant3 |
|
11 |
|
difindi |
|
12 |
11
|
difeq2i |
|
13 |
12
|
a1i |
|
14 |
1 10 13
|
3eqtrd |
|
15 |
|
simp1 |
|
16 |
|
saldifcl |
|
17 |
16
|
3adant3 |
|
18 |
|
saldifcl |
|
19 |
18
|
3adant2 |
|
20 |
|
saluncl |
|
21 |
15 17 19 20
|
syl3anc |
|
22 |
|
saldifcl |
|
23 |
15 21 22
|
syl2anc |
|
24 |
14 23
|
eqeltrd |
|