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Theorem dominf 9855
Description: A nonempty set that is a subset of its union is infinite. This version is proved from ax-cc 9845. See dominfac 9983 for a version proved from ax-ac 9869. The axiom of Regularity is used for this proof, via inf3lem6 9084, and its use is necessary: otherwise the set 𝐴 = {𝐴} or 𝐴 = {∅, 𝐴} (where the second example even has nonempty well-founded part) provides a counterexample. (Contributed by Mario Carneiro, 9-Feb-2013.)
Hypothesis
Ref Expression
dominf.1 𝐴 ∈ V
Assertion
Ref Expression
dominf ((𝐴 ≠ ∅ ∧ 𝐴 𝐴) → ω ≼ 𝐴)

Proof of Theorem dominf
Dummy variables 𝑥 𝑦 𝑤 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 dominf.1 . 2 𝐴 ∈ V
2 neeq1 3075 . . . 4 (𝑥 = 𝐴 → (𝑥 ≠ ∅ ↔ 𝐴 ≠ ∅))
3 id 22 . . . . 5 (𝑥 = 𝐴𝑥 = 𝐴)
4 unieq 4838 . . . . 5 (𝑥 = 𝐴 𝑥 = 𝐴)
53, 4sseq12d 3997 . . . 4 (𝑥 = 𝐴 → (𝑥 𝑥𝐴 𝐴))
62, 5anbi12d 630 . . 3 (𝑥 = 𝐴 → ((𝑥 ≠ ∅ ∧ 𝑥 𝑥) ↔ (𝐴 ≠ ∅ ∧ 𝐴 𝐴)))
7 breq2 5061 . . 3 (𝑥 = 𝐴 → (ω ≼ 𝑥 ↔ ω ≼ 𝐴))
86, 7imbi12d 346 . 2 (𝑥 = 𝐴 → (((𝑥 ≠ ∅ ∧ 𝑥 𝑥) → ω ≼ 𝑥) ↔ ((𝐴 ≠ ∅ ∧ 𝐴 𝐴) → ω ≼ 𝐴)))
9 eqid 2818 . . . 4 (𝑦 ∈ V ↦ {𝑤𝑥 ∣ (𝑤𝑥) ⊆ 𝑦}) = (𝑦 ∈ V ↦ {𝑤𝑥 ∣ (𝑤𝑥) ⊆ 𝑦})
10 eqid 2818 . . . 4 (rec((𝑦 ∈ V ↦ {𝑤𝑥 ∣ (𝑤𝑥) ⊆ 𝑦}), ∅) ↾ ω) = (rec((𝑦 ∈ V ↦ {𝑤𝑥 ∣ (𝑤𝑥) ⊆ 𝑦}), ∅) ↾ ω)
119, 10, 1, 1inf3lem6 9084 . . 3 ((𝑥 ≠ ∅ ∧ 𝑥 𝑥) → (rec((𝑦 ∈ V ↦ {𝑤𝑥 ∣ (𝑤𝑥) ⊆ 𝑦}), ∅) ↾ ω):ω–1-1→𝒫 𝑥)
12 vpwex 5269 . . . 4 𝒫 𝑥 ∈ V
1312f1dom 8519 . . 3 ((rec((𝑦 ∈ V ↦ {𝑤𝑥 ∣ (𝑤𝑥) ⊆ 𝑦}), ∅) ↾ ω):ω–1-1→𝒫 𝑥 → ω ≼ 𝒫 𝑥)
14 pwfi 8807 . . . . . . 7 (𝑥 ∈ Fin ↔ 𝒫 𝑥 ∈ Fin)
1514biimpi 217 . . . . . 6 (𝑥 ∈ Fin → 𝒫 𝑥 ∈ Fin)
16 isfinite 9103 . . . . . 6 (𝑥 ∈ Fin ↔ 𝑥 ≺ ω)
17 isfinite 9103 . . . . . 6 (𝒫 𝑥 ∈ Fin ↔ 𝒫 𝑥 ≺ ω)
1815, 16, 173imtr3i 292 . . . . 5 (𝑥 ≺ ω → 𝒫 𝑥 ≺ ω)
1918con3i 157 . . . 4 (¬ 𝒫 𝑥 ≺ ω → ¬ 𝑥 ≺ ω)
2012domtriom 9853 . . . 4 (ω ≼ 𝒫 𝑥 ↔ ¬ 𝒫 𝑥 ≺ ω)
21 vex 3495 . . . . 5 𝑥 ∈ V
2221domtriom 9853 . . . 4 (ω ≼ 𝑥 ↔ ¬ 𝑥 ≺ ω)
2319, 20, 223imtr4i 293 . . 3 (ω ≼ 𝒫 𝑥 → ω ≼ 𝑥)
2411, 13, 233syl 18 . 2 ((𝑥 ≠ ∅ ∧ 𝑥 𝑥) → ω ≼ 𝑥)
251, 8, 24vtocl 3557 1 ((𝐴 ≠ ∅ ∧ 𝐴 𝐴) → ω ≼ 𝐴)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wa 396   = wceq 1528  wcel 2105  wne 3013  {crab 3139  Vcvv 3492  cin 3932  wss 3933  c0 4288  𝒫 cpw 4535   cuni 4830   class class class wbr 5057  cmpt 5137  cres 5550  1-1wf1 6345  ωcom 7569  reccrdg 8034  cdom 8495  csdm 8496  Fincfn 8497
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1787  ax-4 1801  ax-5 1902  ax-6 1961  ax-7 2006  ax-8 2107  ax-9 2115  ax-10 2136  ax-11 2151  ax-12 2167  ax-ext 2790  ax-rep 5181  ax-sep 5194  ax-nul 5201  ax-pow 5257  ax-pr 5320  ax-un 7450  ax-reg 9044  ax-inf2 9092  ax-cc 9845
This theorem depends on definitions:  df-bi 208  df-an 397  df-or 842  df-3or 1080  df-3an 1081  df-tru 1531  df-ex 1772  df-nf 1776  df-sb 2061  df-mo 2615  df-eu 2647  df-clab 2797  df-cleq 2811  df-clel 2890  df-nfc 2960  df-ne 3014  df-ral 3140  df-rex 3141  df-reu 3142  df-rmo 3143  df-rab 3144  df-v 3494  df-sbc 3770  df-csb 3881  df-dif 3936  df-un 3938  df-in 3940  df-ss 3949  df-pss 3951  df-nul 4289  df-if 4464  df-pw 4537  df-sn 4558  df-pr 4560  df-tp 4562  df-op 4564  df-uni 4831  df-int 4868  df-iun 4912  df-br 5058  df-opab 5120  df-mpt 5138  df-tr 5164  df-id 5453  df-eprel 5458  df-po 5467  df-so 5468  df-fr 5507  df-we 5509  df-xp 5554  df-rel 5555  df-cnv 5556  df-co 5557  df-dm 5558  df-rn 5559  df-res 5560  df-ima 5561  df-pred 6141  df-ord 6187  df-on 6188  df-lim 6189  df-suc 6190  df-iota 6307  df-fun 6350  df-fn 6351  df-f 6352  df-f1 6353  df-fo 6354  df-f1o 6355  df-fv 6356  df-ov 7148  df-oprab 7149  df-mpo 7150  df-om 7570  df-1st 7678  df-2nd 7679  df-wrecs 7936  df-recs 7997  df-rdg 8035  df-1o 8091  df-2o 8092  df-oadd 8095  df-er 8278  df-map 8397  df-en 8498  df-dom 8499  df-sdom 8500  df-fin 8501  df-dju 9318  df-card 9356
This theorem is referenced by:  axgroth3  10241
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