Description: The converse of the singleton of the empty set is empty. (Contributed by Mario Carneiro, 30-Aug-2015)
Ref | Expression | ||
---|---|---|---|
Assertion | cnvsn0 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dfdm4 | ||
2 | dmsn0 | ||
3 | 1 2 | eqtr3i | |
4 | relcnv | ||
5 | relrn0 | ||
6 | 4 5 | ax-mp | |
7 | 3 6 | mpbir |