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Metamath Proof Explorer

Theorem fndm

Description: The domain of a function. (Contributed by NM, 2-Aug-1994)

		Ref	Expression
	Assertion	fndm	$⊢ F Fn A \to dom F = A$

Step	Hyp	Ref	Expression
1		df-fn	$⊢ F Fn A \leftrightarrow (Fun F \land dom F = A)$
2	1	simprbi	$⊢ F Fn A \to dom F = A$