Theorem foeq3 5124

Description: Equality theorem for onto functions. (Contributed by NM, 1-Aug-1994.)

Assertion

Ref	Expression
foeq3	⊢ (𝐴 = 𝐵 → (𝐹:𝐶–onto→𝐴 ↔ 𝐹:𝐶–onto→𝐵))

Proof of Theorem foeq3

Step	Hyp	Ref	Expression
1		eqeq2 2090	. . 3 ⊢ (𝐴 = 𝐵 → (ran 𝐹 = 𝐴 ↔ ran 𝐹 = 𝐵))
2	1	anbi2d 451	. 2 ⊢ (𝐴 = 𝐵 → ((𝐹 Fn 𝐶 ∧ ran 𝐹 = 𝐴) ↔ (𝐹 Fn 𝐶 ∧ ran 𝐹 = 𝐵)))
3		df-fo 4928	. 2 ⊢ (𝐹:𝐶–onto→𝐴 ↔ (𝐹 Fn 𝐶 ∧ ran 𝐹 = 𝐴))
4		df-fo 4928	. 2 ⊢ (𝐹:𝐶–onto→𝐵 ↔ (𝐹 Fn 𝐶 ∧ ran 𝐹 = 𝐵))
5	2, 3, 4	3bitr4g 221	1 ⊢ (𝐴 = 𝐵 → (𝐹:𝐶–onto→𝐴 ↔ 𝐹:𝐶–onto→𝐵))

Syntax hints:   → wi 4   ∧ wa 102   ↔ wb 103   = wceq 1284  ran crn 4364   Fn wfn 4917  –onto→wfo 4920

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-5 1376  ax-gen 1378  ax-4 1440  ax-17 1459  ax-ext 2063

This theorem depends on definitions:  df-bi 115  df-cleq 2074  df-fo 4928

This theorem is referenced by:  f1oeq3  5139  foeq123d  5142  resdif  5168  ffoss  5178