Description: The singleton of a set is not empty. (Contributed by NM, 14-Dec-2008)
Ref | Expression | ||
---|---|---|---|
Assertion | snnzg | |- ( A e. V -> { A } =/= (/) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | snidg | |- ( A e. V -> A e. { A } ) |
|
2 | 1 | ne0d | |- ( A e. V -> { A } =/= (/) ) |