Metamath Proof Explorer
Description: Property of identity relation, see also extep , extssr and the comment
of df-ssr . (Contributed by Peter Mazsa, 5-Jul-2019)
|
|
Ref |
Expression |
|
Assertion |
extid |
|
Proof
Step |
Hyp |
Ref |
Expression |
1 |
|
cnvi |
|
2 |
1
|
eceq2i |
|
3 |
|
ecidsn |
|
4 |
2 3
|
eqtri |
|
5 |
1
|
eceq2i |
|
6 |
|
ecidsn |
|
7 |
5 6
|
eqtri |
|
8 |
4 7
|
eqeq12i |
|
9 |
|
sneqbg |
|
10 |
8 9
|
syl5bb |
|