Theorem foeq3 5301

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 2124	. . 3 ⊢ (𝐴 = 𝐵 → (ran 𝐹 = 𝐴 ↔ ran 𝐹 = 𝐵))
2	1	anbi2d 457	. 2 ⊢ (𝐴 = 𝐵 → ((𝐹 Fn 𝐶 ∧ ran 𝐹 = 𝐴) ↔ (𝐹 Fn 𝐶 ∧ ran 𝐹 = 𝐵)))
3		df-fo 5087	. 2 ⊢ (𝐹:𝐶–onto→𝐴 ↔ (𝐹 Fn 𝐶 ∧ ran 𝐹 = 𝐴))
4		df-fo 5087	. 2 ⊢ (𝐹:𝐶–onto→𝐵 ↔ (𝐹 Fn 𝐶 ∧ ran 𝐹 = 𝐵))
5	2, 3, 4	3bitr4g 222	1 ⊢ (𝐴 = 𝐵 → (𝐹:𝐶–onto→𝐴 ↔ 𝐹:𝐶–onto→𝐵))

Syntax hints:   → wi 4   ∧ wa 103   ↔ wb 104   = wceq 1314  ran crn 4500   Fn wfn 5076  –onto→wfo 5079

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-5 1406  ax-gen 1408  ax-4 1470  ax-17 1489  ax-ext 2097

This theorem depends on definitions:  df-bi 116  df-cleq 2108  df-fo 5087

This theorem is referenced by:  f1oeq3  5316  foeq123d  5319  resdif  5345  ffoss  5355  fifo  6820  enumct  6952  ctssexmid  6974  exmidfodomrlemr  7006  exmidfodomrlemrALT  7007  qnnen  11789  unct  11797  subctctexmid  12888