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Theorem foeq2 6799
Description: Equality theorem for onto functions. (Contributed by NM, 1-Aug-1994.)
Assertion
Ref Expression
foeq2 (𝐴 = 𝐵 → (𝐹:𝐴onto𝐶𝐹:𝐵onto𝐶))

Proof of Theorem foeq2
StepHypRef Expression
1 fneq2 6638 . . 3 (𝐴 = 𝐵 → (𝐹 Fn 𝐴𝐹 Fn 𝐵))
21anbi1d 630 . 2 (𝐴 = 𝐵 → ((𝐹 Fn 𝐴 ∧ ran 𝐹 = 𝐶) ↔ (𝐹 Fn 𝐵 ∧ ran 𝐹 = 𝐶)))
3 df-fo 6546 . 2 (𝐹:𝐴onto𝐶 ↔ (𝐹 Fn 𝐴 ∧ ran 𝐹 = 𝐶))
4 df-fo 6546 . 2 (𝐹:𝐵onto𝐶 ↔ (𝐹 Fn 𝐵 ∧ ran 𝐹 = 𝐶))
52, 3, 43bitr4g 313 1 (𝐴 = 𝐵 → (𝐹:𝐴onto𝐶𝐹:𝐵onto𝐶))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 205  wa 396   = wceq 1541  ran crn 5676   Fn wfn 6535  ontowfo 6538
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1913  ax-6 1971  ax-7 2011  ax-9 2116  ax-ext 2703
This theorem depends on definitions:  df-bi 206  df-an 397  df-ex 1782  df-cleq 2724  df-fn 6543  df-fo 6546
This theorem is referenced by:  foco  6816  f1oeq2  6819  foeq123d  6823  tposfo  8234  brwdom  9558  brwdom2  9564  canthwdom  9570  cfslb2n  10259  0ramcl  16952  ghmcyg  19758  txcmpb  23139  qtoptopon  23199  fsupprnfi  31901  opidon2OLD  36710  fnfocofob  45773  fullthinc  47619
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