Description: Empty ordered pair class abstraction. (Contributed by AV, 29-Oct-2021)
Ref | Expression | ||
---|---|---|---|
Assertion | opab0 | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | opabn0 | |
|
2 | df-ne | |
|
3 | 2exnaln | |
|
4 | 1 2 3 | 3bitr3i | |
5 | 4 | con4bii | |