Description: Any set weakly dominates the empty set. (Contributed by Stefan O'Rear, 11-Feb-2015)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | 0wdom | |- ( X e. V -> (/) ~<_* X ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | eqid | |- (/) = (/) |
|
| 2 | 1 | orci | |- ( (/) = (/) \/ E. z z : X -onto-> (/) ) |
| 3 | brwdom | |- ( X e. V -> ( (/) ~<_* X <-> ( (/) = (/) \/ E. z z : X -onto-> (/) ) ) ) |
|
| 4 | 2 3 | mpbiri | |- ( X e. V -> (/) ~<_* X ) |