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