Description: A function's value belongs to its codomain. (Contributed by NM, 6-Apr-2005)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | ffvelcdmi.1 | ⊢ 𝐹 : 𝐴 ⟶ 𝐵 | |
| Assertion | ffvelcdmi | ⊢ ( 𝐶 ∈ 𝐴 → ( 𝐹 ‘ 𝐶 ) ∈ 𝐵 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ffvelcdmi.1 | ⊢ 𝐹 : 𝐴 ⟶ 𝐵 | |
| 2 | ffvelcdm | ⊢ ( ( 𝐹 : 𝐴 ⟶ 𝐵 ∧ 𝐶 ∈ 𝐴 ) → ( 𝐹 ‘ 𝐶 ) ∈ 𝐵 ) | |
| 3 | 1 2 | mpan | ⊢ ( 𝐶 ∈ 𝐴 → ( 𝐹 ‘ 𝐶 ) ∈ 𝐵 ) |