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Description: Define a function (mapping) with domain and codomain. Definition 6.15(3) of TakeutiZaring p. 27. F : A --> B can be read as " F is a function from A to B ". For alternate definitions, see dff2 , dff3 , and dff4 . (Contributed by NM, 1-Aug-1994)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-f | ⊢ ( 𝐹 : 𝐴 ⟶ 𝐵 ↔ ( 𝐹 Fn 𝐴 ∧ ran 𝐹 ⊆ 𝐵 ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 0 | cF | ⊢ 𝐹 | |
| 1 | cA | ⊢ 𝐴 | |
| 2 | cB | ⊢ 𝐵 | |
| 3 | 1 2 0 | wf | ⊢ 𝐹 : 𝐴 ⟶ 𝐵 |
| 4 | 0 1 | wfn | ⊢ 𝐹 Fn 𝐴 |
| 5 | 0 | crn | ⊢ ran 𝐹 |
| 6 | 5 2 | wss | ⊢ ran 𝐹 ⊆ 𝐵 |
| 7 | 4 6 | wa | ⊢ ( 𝐹 Fn 𝐴 ∧ ran 𝐹 ⊆ 𝐵 ) |
| 8 | 3 7 | wb | ⊢ ( 𝐹 : 𝐴 ⟶ 𝐵 ↔ ( 𝐹 Fn 𝐴 ∧ ran 𝐹 ⊆ 𝐵 ) ) |