Metamath Proof Explorer
Description: An equality inference for the proper subclass relationship.
(Contributed by NM, 9-Jun-2004)
|
|
Ref |
Expression |
|
Hypotheses |
psseq1i.1 |
|
|
|
psseq12i.2 |
|
|
Assertion |
psseq12i |
|
Proof
Step |
Hyp |
Ref |
Expression |
1 |
|
psseq1i.1 |
|
2 |
|
psseq12i.2 |
|
3 |
1
|
psseq1i |
|
4 |
2
|
psseq2i |
|
5 |
3 4
|
bitri |
|