Metamath Proof Explorer


Theorem fex

Description: If the domain of a mapping is a set, the function is a set. (Contributed by NM, 3-Oct-1999)

Ref Expression
Assertion fex F : A B A C F V

Proof

Step Hyp Ref Expression
1 ffn F : A B F Fn A
2 fnex F Fn A A C F V
3 1 2 sylan F : A B A C F V