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Theorem dominf 9219
 Description: A nonempty set that is a subset of its union is infinite. This version is proved from ax-cc 9209. See dominfac 9347 for a version proved from ax-ac 9233. The axiom of Regularity is used for this proof, via inf3lem6 8482, 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 2852 . . . 4 (𝑥 = 𝐴 → (𝑥 ≠ ∅ ↔ 𝐴 ≠ ∅))
3 id 22 . . . . 5 (𝑥 = 𝐴𝑥 = 𝐴)
4 unieq 4415 . . . . 5 (𝑥 = 𝐴 𝑥 = 𝐴)
53, 4sseq12d 3618 . . . 4 (𝑥 = 𝐴 → (𝑥 𝑥𝐴 𝐴))
62, 5anbi12d 746 . . 3 (𝑥 = 𝐴 → ((𝑥 ≠ ∅ ∧ 𝑥 𝑥) ↔ (𝐴 ≠ ∅ ∧ 𝐴 𝐴)))
7 breq2 4622 . . 3 (𝑥 = 𝐴 → (ω ≼ 𝑥 ↔ ω ≼ 𝐴))
86, 7imbi12d 334 . 2 (𝑥 = 𝐴 → (((𝑥 ≠ ∅ ∧ 𝑥 𝑥) → ω ≼ 𝑥) ↔ ((𝐴 ≠ ∅ ∧ 𝐴 𝐴) → ω ≼ 𝐴)))
9 eqid 2621 . . . 4 (𝑦 ∈ V ↦ {𝑤𝑥 ∣ (𝑤𝑥) ⊆ 𝑦}) = (𝑦 ∈ V ↦ {𝑤𝑥 ∣ (𝑤𝑥) ⊆ 𝑦})
10 eqid 2621 . . . 4 (rec((𝑦 ∈ V ↦ {𝑤𝑥 ∣ (𝑤𝑥) ⊆ 𝑦}), ∅) ↾ ω) = (rec((𝑦 ∈ V ↦ {𝑤𝑥 ∣ (𝑤𝑥) ⊆ 𝑦}), ∅) ↾ ω)
119, 10, 1, 1inf3lem6 8482 . . 3 ((𝑥 ≠ ∅ ∧ 𝑥 𝑥) → (rec((𝑦 ∈ V ↦ {𝑤𝑥 ∣ (𝑤𝑥) ⊆ 𝑦}), ∅) ↾ ω):ω–1-1→𝒫 𝑥)
12 vpwex 4814 . . . 4 𝒫 𝑥 ∈ V
1312f1dom 7929 . . 3 ((rec((𝑦 ∈ V ↦ {𝑤𝑥 ∣ (𝑤𝑥) ⊆ 𝑦}), ∅) ↾ ω):ω–1-1→𝒫 𝑥 → ω ≼ 𝒫 𝑥)
14 pwfi 8213 . . . . . . 7 (𝑥 ∈ Fin ↔ 𝒫 𝑥 ∈ Fin)
1514biimpi 206 . . . . . 6 (𝑥 ∈ Fin → 𝒫 𝑥 ∈ Fin)
16 isfinite 8501 . . . . . 6 (𝑥 ∈ Fin ↔ 𝑥 ≺ ω)
17 isfinite 8501 . . . . . 6 (𝒫 𝑥 ∈ Fin ↔ 𝒫 𝑥 ≺ ω)
1815, 16, 173imtr3i 280 . . . . 5 (𝑥 ≺ ω → 𝒫 𝑥 ≺ ω)
1918con3i 150 . . . 4 (¬ 𝒫 𝑥 ≺ ω → ¬ 𝑥 ≺ ω)
2012domtriom 9217 . . . 4 (ω ≼ 𝒫 𝑥 ↔ ¬ 𝒫 𝑥 ≺ ω)
21 vex 3192 . . . . 5 𝑥 ∈ V
2221domtriom 9217 . . . 4 (ω ≼ 𝑥 ↔ ¬ 𝑥 ≺ ω)
2319, 20, 223imtr4i 281 . . 3 (ω ≼ 𝒫 𝑥 → ω ≼ 𝑥)
2411, 13, 233syl 18 . 2 ((𝑥 ≠ ∅ ∧ 𝑥 𝑥) → ω ≼ 𝑥)
251, 8, 24vtocl 3248 1 ((𝐴 ≠ ∅ ∧ 𝐴 𝐴) → ω ≼ 𝐴)
 Colors of variables: wff setvar class Syntax hints:  ¬ wn 3   → wi 4   ∧ wa 384   = wceq 1480   ∈ wcel 1987   ≠ wne 2790  {crab 2911  Vcvv 3189   ∩ cin 3558   ⊆ wss 3559  ∅c0 3896  𝒫 cpw 4135  ∪ cuni 4407   class class class wbr 4618   ↦ cmpt 4678   ↾ cres 5081  –1-1→wf1 5849  ωcom 7019  reccrdg 7457   ≼ cdom 7905   ≺ csdm 7906  Fincfn 7907 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1719  ax-4 1734  ax-5 1836  ax-6 1885  ax-7 1932  ax-8 1989  ax-9 1996  ax-10 2016  ax-11 2031  ax-12 2044  ax-13 2245  ax-ext 2601  ax-rep 4736  ax-sep 4746  ax-nul 4754  ax-pow 4808  ax-pr 4872  ax-un 6909  ax-reg 8449  ax-inf2 8490  ax-cc 9209 This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-3or 1037  df-3an 1038  df-tru 1483  df-ex 1702  df-nf 1707  df-sb 1878  df-eu 2473  df-mo 2474  df-clab 2608  df-cleq 2614  df-clel 2617  df-nfc 2750  df-ne 2791  df-ral 2912  df-rex 2913  df-reu 2914  df-rmo 2915  df-rab 2916  df-v 3191  df-sbc 3422  df-csb 3519  df-dif 3562  df-un 3564  df-in 3566  df-ss 3573  df-pss 3575  df-nul 3897  df-if 4064  df-pw 4137  df-sn 4154  df-pr 4156  df-tp 4158  df-op 4160  df-uni 4408  df-int 4446  df-iun 4492  df-br 4619  df-opab 4679  df-mpt 4680  df-tr 4718  df-eprel 4990  df-id 4994  df-po 5000  df-so 5001  df-fr 5038  df-we 5040  df-xp 5085  df-rel 5086  df-cnv 5087  df-co 5088  df-dm 5089  df-rn 5090  df-res 5091  df-ima 5092  df-pred 5644  df-ord 5690  df-on 5691  df-lim 5692  df-suc 5693  df-iota 5815  df-fun 5854  df-fn 5855  df-f 5856  df-f1 5857  df-fo 5858  df-f1o 5859  df-fv 5860  df-ov 6613  df-oprab 6614  df-mpt2 6615  df-om 7020  df-1st 7120  df-2nd 7121  df-wrecs 7359  df-recs 7420  df-rdg 7458  df-1o 7512  df-2o 7513  df-oadd 7516  df-er 7694  df-map 7811  df-en 7908  df-dom 7909  df-sdom 7910  df-fin 7911  df-card 8717  df-cda 8942 This theorem is referenced by:  axgroth3  9605
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