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Theorem fodomg 9929
Description: An onto function implies dominance of domain over range. Lemma 10.20 of [Kunen] p. 30. This theorem uses the axiom of choice ac7g 9881. The axiom of choice is not needed for finite sets, see fodomfi 8781. See also fodomnum 9468. (Contributed by NM, 23-Jul-2004.) (Proof shortened by BJ, 20-May-2024.)
Assertion
Ref Expression
fodomg (𝐴𝑉 → (𝐹:𝐴onto𝐵𝐵𝐴))

Proof of Theorem fodomg
StepHypRef Expression
1 numth3 9877 . 2 (𝐴𝑉𝐴 ∈ dom card)
2 fodomnum 9468 . 2 (𝐴 ∈ dom card → (𝐹:𝐴onto𝐵𝐵𝐴))
31, 2syl 17 1 (𝐴𝑉 → (𝐹:𝐴onto𝐵𝐵𝐴))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wcel 2115   class class class wbr 5047  dom cdm 5536  ontowfo 6334  cdom 8490  cardccrd 9348
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 1912  ax-6 1971  ax-7 2016  ax-8 2117  ax-9 2125  ax-10 2146  ax-11 2162  ax-12 2179  ax-ext 2796  ax-rep 5171  ax-sep 5184  ax-nul 5191  ax-pow 5247  ax-pr 5311  ax-un 7444  ax-ac2 9870
This theorem depends on definitions:  df-bi 210  df-an 400  df-or 845  df-3or 1085  df-3an 1086  df-tru 1541  df-ex 1782  df-nf 1786  df-sb 2071  df-mo 2624  df-eu 2655  df-clab 2803  df-cleq 2817  df-clel 2896  df-nfc 2964  df-ne 3014  df-ral 3137  df-rex 3138  df-reu 3139  df-rmo 3140  df-rab 3141  df-v 3481  df-sbc 3758  df-csb 3866  df-dif 3921  df-un 3923  df-in 3925  df-ss 3935  df-pss 3937  df-nul 4275  df-if 4449  df-pw 4522  df-sn 4549  df-pr 4551  df-tp 4553  df-op 4555  df-uni 4820  df-int 4858  df-iun 4902  df-br 5048  df-opab 5110  df-mpt 5128  df-tr 5154  df-id 5441  df-eprel 5446  df-po 5455  df-so 5456  df-fr 5495  df-se 5496  df-we 5497  df-xp 5542  df-rel 5543  df-cnv 5544  df-co 5545  df-dm 5546  df-rn 5547  df-res 5548  df-ima 5549  df-pred 6129  df-ord 6175  df-on 6176  df-suc 6178  df-iota 6295  df-fun 6338  df-fn 6339  df-f 6340  df-f1 6341  df-fo 6342  df-f1o 6343  df-fv 6344  df-isom 6345  df-riota 7096  df-ov 7141  df-oprab 7142  df-mpo 7143  df-1st 7672  df-2nd 7673  df-wrecs 7930  df-recs 7991  df-er 8272  df-map 8391  df-en 8493  df-dom 8494  df-card 9352  df-acn 9355  df-ac 9527
This theorem is referenced by:  fodom  9930  dmct  9931  fodomb  9933  imadomg  9941  fnrndomg  9943  disjinfi  41661
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