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Description: The singleton of a set is not empty. (Contributed by Glauco Siliprandi, 3-Mar-2021)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | snn0d.1 | ||
| Assertion | snn0d |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | snn0d.1 | ||
| 2 | snnzg | ||
| 3 | 1 2 | syl |