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Metamath Proof Explorer

Theorem fofn

Description: An onto mapping is a function on its domain. (Contributed by NM, 16-Dec-2008)

		Ref	Expression
	Assertion	fofn	$⊢ F : A \underset{onto}{⟶} B \to F Fn A$

Step	Hyp	Ref	Expression
1		fof	$⊢ F : A \underset{onto}{⟶} B \to F : A ⟶ B$
2	1	ffnd	$⊢ F : A \underset{onto}{⟶} B \to F Fn A$