Description: Equality inference for unordered pairs. (Contributed by NM, 19-Oct-2012)
Ref | Expression | ||
---|---|---|---|
Hypotheses | preq1i.1 | |
|
preq12i.2 | |
||
Assertion | preq12i | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | preq1i.1 | |
|
2 | preq12i.2 | |
|
3 | preq12 | |
|
4 | 1 2 3 | mp2an | |