Step |
Hyp |
Ref |
Expression |
1 |
|
oppgbas.1 |
|
2 |
|
eqid |
|
3 |
1 2
|
oppgbas |
|
4 |
3
|
a1i |
|
5 |
|
eqidd |
|
6 |
|
eqid |
|
7 |
1 6
|
oppgid |
|
8 |
7
|
a1i |
|
9 |
|
grpmnd |
|
10 |
1
|
oppgmnd |
|
11 |
9 10
|
syl |
|
12 |
|
eqid |
|
13 |
2 12
|
grpinvcl |
|
14 |
|
eqid |
|
15 |
|
eqid |
|
16 |
14 1 15
|
oppgplus |
|
17 |
2 14 6 12
|
grprinv |
|
18 |
16 17
|
syl5eq |
|
19 |
4 5 8 11 13 18
|
isgrpd2 |
|