Metamath Proof Explorer
Description: Identity law for the rank function. (Contributed by NM, 3-Oct-2003)
(Revised by Mario Carneiro, 17-Nov-2014)
|
|
Ref |
Expression |
|
Hypothesis |
rankid.1 |
|
|
Assertion |
rankid |
|
Proof
Step |
Hyp |
Ref |
Expression |
1 |
|
rankid.1 |
|
2 |
|
unir1 |
|
3 |
1 2
|
eleqtrri |
|
4 |
|
rankidb |
|
5 |
3 4
|
ax-mp |
|