Description: The singleton of a set is not empty. (Contributed by Glauco Siliprandi, 3-Mar-2021)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | snn0d.1 | ⊢ ( 𝜑 → 𝐴 ∈ 𝑉 ) | |
| Assertion | snn0d | ⊢ ( 𝜑 → { 𝐴 } ≠ ∅ ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | snn0d.1 | ⊢ ( 𝜑 → 𝐴 ∈ 𝑉 ) | |
| 2 | snnzg | ⊢ ( 𝐴 ∈ 𝑉 → { 𝐴 } ≠ ∅ ) | |
| 3 | 1 2 | syl | ⊢ ( 𝜑 → { 𝐴 } ≠ ∅ ) |