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Description: The membership relation is nonempty. (Contributed by AV, 19-Jun-2022)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | epn0 | ⊢ E ≠ ∅ |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | 0sn0ep | ⊢ ∅ E { ∅ } | |
| 2 | brne0 | ⊢ ( ∅ E { ∅ } → E ≠ ∅ ) | |
| 3 | 1 2 | ax-mp | ⊢ E ≠ ∅ |