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Theorem dominf 9602
Description: A nonempty set that is a subset of its union is infinite. This version is proved from ax-cc 9592. See dominfac 9730 for a version proved from ax-ac 9616. The axiom of Regularity is used for this proof, via inf3lem6 8827, 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 3031 . . . 4 (𝑥 = 𝐴 → (𝑥 ≠ ∅ ↔ 𝐴 ≠ ∅))
3 id 22 . . . . 5 (𝑥 = 𝐴𝑥 = 𝐴)
4 unieq 4679 . . . . 5 (𝑥 = 𝐴 𝑥 = 𝐴)
53, 4sseq12d 3853 . . . 4 (𝑥 = 𝐴 → (𝑥 𝑥𝐴 𝐴))
62, 5anbi12d 624 . . 3 (𝑥 = 𝐴 → ((𝑥 ≠ ∅ ∧ 𝑥 𝑥) ↔ (𝐴 ≠ ∅ ∧ 𝐴 𝐴)))
7 breq2 4890 . . 3 (𝑥 = 𝐴 → (ω ≼ 𝑥 ↔ ω ≼ 𝐴))
86, 7imbi12d 336 . 2 (𝑥 = 𝐴 → (((𝑥 ≠ ∅ ∧ 𝑥 𝑥) → ω ≼ 𝑥) ↔ ((𝐴 ≠ ∅ ∧ 𝐴 𝐴) → ω ≼ 𝐴)))
9 eqid 2778 . . . 4 (𝑦 ∈ V ↦ {𝑤𝑥 ∣ (𝑤𝑥) ⊆ 𝑦}) = (𝑦 ∈ V ↦ {𝑤𝑥 ∣ (𝑤𝑥) ⊆ 𝑦})
10 eqid 2778 . . . 4 (rec((𝑦 ∈ V ↦ {𝑤𝑥 ∣ (𝑤𝑥) ⊆ 𝑦}), ∅) ↾ ω) = (rec((𝑦 ∈ V ↦ {𝑤𝑥 ∣ (𝑤𝑥) ⊆ 𝑦}), ∅) ↾ ω)
119, 10, 1, 1inf3lem6 8827 . . 3 ((𝑥 ≠ ∅ ∧ 𝑥 𝑥) → (rec((𝑦 ∈ V ↦ {𝑤𝑥 ∣ (𝑤𝑥) ⊆ 𝑦}), ∅) ↾ ω):ω–1-1→𝒫 𝑥)
12 vpwex 5089 . . . 4 𝒫 𝑥 ∈ V
1312f1dom 8263 . . 3 ((rec((𝑦 ∈ V ↦ {𝑤𝑥 ∣ (𝑤𝑥) ⊆ 𝑦}), ∅) ↾ ω):ω–1-1→𝒫 𝑥 → ω ≼ 𝒫 𝑥)
14 pwfi 8549 . . . . . . 7 (𝑥 ∈ Fin ↔ 𝒫 𝑥 ∈ Fin)
1514biimpi 208 . . . . . 6 (𝑥 ∈ Fin → 𝒫 𝑥 ∈ Fin)
16 isfinite 8846 . . . . . 6 (𝑥 ∈ Fin ↔ 𝑥 ≺ ω)
17 isfinite 8846 . . . . . 6 (𝒫 𝑥 ∈ Fin ↔ 𝒫 𝑥 ≺ ω)
1815, 16, 173imtr3i 283 . . . . 5 (𝑥 ≺ ω → 𝒫 𝑥 ≺ ω)
1918con3i 152 . . . 4 (¬ 𝒫 𝑥 ≺ ω → ¬ 𝑥 ≺ ω)
2012domtriom 9600 . . . 4 (ω ≼ 𝒫 𝑥 ↔ ¬ 𝒫 𝑥 ≺ ω)
21 vex 3401 . . . . 5 𝑥 ∈ V
2221domtriom 9600 . . . 4 (ω ≼ 𝑥 ↔ ¬ 𝑥 ≺ ω)
2319, 20, 223imtr4i 284 . . 3 (ω ≼ 𝒫 𝑥 → ω ≼ 𝑥)
2411, 13, 233syl 18 . 2 ((𝑥 ≠ ∅ ∧ 𝑥 𝑥) → ω ≼ 𝑥)
251, 8, 24vtocl 3460 1 ((𝐴 ≠ ∅ ∧ 𝐴 𝐴) → ω ≼ 𝐴)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wa 386   = wceq 1601  wcel 2107  wne 2969  {crab 3094  Vcvv 3398  cin 3791  wss 3792  c0 4141  𝒫 cpw 4379   cuni 4671   class class class wbr 4886  cmpt 4965  cres 5357  1-1wf1 6132  ωcom 7343  reccrdg 7788  cdom 8239  csdm 8240  Fincfn 8241
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1839  ax-4 1853  ax-5 1953  ax-6 2021  ax-7 2055  ax-8 2109  ax-9 2116  ax-10 2135  ax-11 2150  ax-12 2163  ax-13 2334  ax-ext 2754  ax-rep 5006  ax-sep 5017  ax-nul 5025  ax-pow 5077  ax-pr 5138  ax-un 7226  ax-reg 8786  ax-inf2 8835  ax-cc 9592
This theorem depends on definitions:  df-bi 199  df-an 387  df-or 837  df-3or 1072  df-3an 1073  df-tru 1605  df-ex 1824  df-nf 1828  df-sb 2012  df-mo 2551  df-eu 2587  df-clab 2764  df-cleq 2770  df-clel 2774  df-nfc 2921  df-ne 2970  df-ral 3095  df-rex 3096  df-reu 3097  df-rmo 3098  df-rab 3099  df-v 3400  df-sbc 3653  df-csb 3752  df-dif 3795  df-un 3797  df-in 3799  df-ss 3806  df-pss 3808  df-nul 4142  df-if 4308  df-pw 4381  df-sn 4399  df-pr 4401  df-tp 4403  df-op 4405  df-uni 4672  df-int 4711  df-iun 4755  df-br 4887  df-opab 4949  df-mpt 4966  df-tr 4988  df-id 5261  df-eprel 5266  df-po 5274  df-so 5275  df-fr 5314  df-we 5316  df-xp 5361  df-rel 5362  df-cnv 5363  df-co 5364  df-dm 5365  df-rn 5366  df-res 5367  df-ima 5368  df-pred 5933  df-ord 5979  df-on 5980  df-lim 5981  df-suc 5982  df-iota 6099  df-fun 6137  df-fn 6138  df-f 6139  df-f1 6140  df-fo 6141  df-f1o 6142  df-fv 6143  df-ov 6925  df-oprab 6926  df-mpt2 6927  df-om 7344  df-1st 7445  df-2nd 7446  df-wrecs 7689  df-recs 7751  df-rdg 7789  df-1o 7843  df-2o 7844  df-oadd 7847  df-er 8026  df-map 8142  df-en 8242  df-dom 8243  df-sdom 8244  df-fin 8245  df-card 9098  df-cda 9325
This theorem is referenced by:  axgroth3  9988
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