Description: If an ordered pair has an element, then its arguments are sets. (Contributed by Mario Carneiro, 26-Apr-2015)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | oprcl | |- ( C e. <. A , B >. -> ( A e. _V /\ B e. _V ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | n0i | |- ( C e. <. A , B >. -> -. <. A , B >. = (/) ) |
|
| 2 | opprc | |- ( -. ( A e. _V /\ B e. _V ) -> <. A , B >. = (/) ) |
|
| 3 | 1 2 | nsyl2 | |- ( C e. <. A , B >. -> ( A e. _V /\ B e. _V ) ) |