Theorem f1dmOLD

Description: Obsolete version of f1dm as of 29-May-2024. (Contributed by NM, 8-Mar-2014) (Proof modification is discouraged.) (New usage is discouraged.)

	Ref	Expression
Assertion	f1dmOLD	$$⊢F:A\underset{1-1}{⟶}B\to \mathrm{dom}F=A$$

Proof

Step	Hyp	Ref	Expression
1		f1fn	$$⊢F:A\underset{1-1}{⟶}B\to FFnA$$
2		fndm	$$⊢FFnA\to \mathrm{dom}F=A$$
3	1 2	syl	$$⊢F:A\underset{1-1}{⟶}B\to \mathrm{dom}F=A$$