Theorem f1dm 5256

Description: The domain of a one-to-one mapping. (Contributed by NM, 8-Mar-2014.)

Assertion

Ref	Expression
f1dm	⊢ (𝐹:𝐴–1-1→𝐵 → dom 𝐹 = 𝐴)

Proof of Theorem f1dm

Step	Hyp	Ref	Expression
1		f1fn 5253	. 2 ⊢ (𝐹:𝐴–1-1→𝐵 → 𝐹 Fn 𝐴)
2		fndm 5147	. 2 ⊢ (𝐹 Fn 𝐴 → dom 𝐹 = 𝐴)
3	1, 2	syl 14	1 ⊢ (𝐹:𝐴–1-1→𝐵 → dom 𝐹 = 𝐴)

Syntax hints:   → wi 4   = wceq 1296  dom cdm 4467   Fn wfn 5044  –1-1→wf1 5046

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 105  ax-ia2 106

This theorem depends on definitions:  df-bi 116  df-fn 5052  df-f 5053  df-f1 5054

This theorem is referenced by:  fun11iun  5309  tposf12  6072  f1dmvrnfibi  6733  f1vrnfibi  6734  exmidfodomrlemim  6924  exmidsbthrlem  12621