Description: One-to-one onto mapping of the empty set. (Contributed by NM, 10-Sep-2004)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | f1o0 | ⊢ ∅ : ∅ –1-1-onto→ ∅ |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | eqid | ⊢ ∅ = ∅ | |
| 2 | f1o00 | ⊢ ( ∅ : ∅ –1-1-onto→ ∅ ↔ ( ∅ = ∅ ∧ ∅ = ∅ ) ) | |
| 3 | 1 1 2 | mpbir2an | ⊢ ∅ : ∅ –1-1-onto→ ∅ |