Theorem ffn

Description: A mapping is a function with domain. (Contributed by NM, 2-Aug-1994)

	Ref	Expression
Assertion	ffn	$$⊢F:A⟶B\to FFnA$$

Proof

Step	Hyp	Ref	Expression
1		df-f	$$⊢F:A⟶B\leftrightarrow \left(FFnA\wedge \mathrm{ran}F\subseteq B\right)$$
2	1	simplbi	$$⊢F:A⟶B\to FFnA$$