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| Mirrors > Home > MPE Home > Th. List > f1oi | Structured version Visualization version GIF version | ||
| Description: A restriction of the identity relation is a one-to-one onto function. (Contributed by NM, 30-Apr-1998.) (Proof shortened by Andrew Salmon, 22-Oct-2011.) |
| Ref | Expression |
|---|---|
| f1oi | ⊢ ( I ↾ 𝐴):𝐴–1-1-onto→𝐴 |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | fnresi 6610 | . 2 ⊢ ( I ↾ 𝐴) Fn 𝐴 | |
| 2 | cnvresid 6560 | . . . 4 ⊢ ◡( I ↾ 𝐴) = ( I ↾ 𝐴) | |
| 3 | 2 | fneq1i 6578 | . . 3 ⊢ (◡( I ↾ 𝐴) Fn 𝐴 ↔ ( I ↾ 𝐴) Fn 𝐴) |
| 4 | 1, 3 | mpbir 231 | . 2 ⊢ ◡( I ↾ 𝐴) Fn 𝐴 |
| 5 | dff1o4 6771 | . 2 ⊢ (( I ↾ 𝐴):𝐴–1-1-onto→𝐴 ↔ (( I ↾ 𝐴) Fn 𝐴 ∧ ◡( I ↾ 𝐴) Fn 𝐴)) | |
| 6 | 1, 4, 5 | mpbir2an 711 | 1 ⊢ ( I ↾ 𝐴):𝐴–1-1-onto→𝐴 |
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