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Description: A one-to-one function with the domain { 0, 1 ,2 } in terms of function values. (Contributed by Alexander van der Vekens, 26-Jan-2018)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | f13idfv.a | ⊢ 𝐴 = ( 0 ... 2 ) | |
| Assertion | f13idfv | ⊢ ( 𝐹 : 𝐴 –1-1→ 𝐵 ↔ ( 𝐹 : 𝐴 ⟶ 𝐵 ∧ ( ( 𝐹 ‘ 0 ) ≠ ( 𝐹 ‘ 1 ) ∧ ( 𝐹 ‘ 0 ) ≠ ( 𝐹 ‘ 2 ) ∧ ( 𝐹 ‘ 1 ) ≠ ( 𝐹 ‘ 2 ) ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | f13idfv.a | ⊢ 𝐴 = ( 0 ... 2 ) | |
| 2 | 0z | ⊢ 0 ∈ ℤ | |
| 3 | 1z | ⊢ 1 ∈ ℤ | |
| 4 | 2z | ⊢ 2 ∈ ℤ | |
| 5 | 2 3 4 | 3pm3.2i | ⊢ ( 0 ∈ ℤ ∧ 1 ∈ ℤ ∧ 2 ∈ ℤ ) |
| 6 | 0ne1 | ⊢ 0 ≠ 1 | |
| 7 | 0ne2 | ⊢ 0 ≠ 2 | |
| 8 | 1ne2 | ⊢ 1 ≠ 2 | |
| 9 | 6 7 8 | 3pm3.2i | ⊢ ( 0 ≠ 1 ∧ 0 ≠ 2 ∧ 1 ≠ 2 ) |
| 10 | fz0tp | ⊢ ( 0 ... 2 ) = { 0 , 1 , 2 } | |
| 11 | 1 10 | eqtri | ⊢ 𝐴 = { 0 , 1 , 2 } |
| 12 | 11 | f13dfv | ⊢ ( ( ( 0 ∈ ℤ ∧ 1 ∈ ℤ ∧ 2 ∈ ℤ ) ∧ ( 0 ≠ 1 ∧ 0 ≠ 2 ∧ 1 ≠ 2 ) ) → ( 𝐹 : 𝐴 –1-1→ 𝐵 ↔ ( 𝐹 : 𝐴 ⟶ 𝐵 ∧ ( ( 𝐹 ‘ 0 ) ≠ ( 𝐹 ‘ 1 ) ∧ ( 𝐹 ‘ 0 ) ≠ ( 𝐹 ‘ 2 ) ∧ ( 𝐹 ‘ 1 ) ≠ ( 𝐹 ‘ 2 ) ) ) ) ) |
| 13 | 5 9 12 | mp2an | ⊢ ( 𝐹 : 𝐴 –1-1→ 𝐵 ↔ ( 𝐹 : 𝐴 ⟶ 𝐵 ∧ ( ( 𝐹 ‘ 0 ) ≠ ( 𝐹 ‘ 1 ) ∧ ( 𝐹 ‘ 0 ) ≠ ( 𝐹 ‘ 2 ) ∧ ( 𝐹 ‘ 1 ) ≠ ( 𝐹 ‘ 2 ) ) ) ) |