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Theorem infn0 9338
Description: An infinite set is not empty. For a shorter proof using ax-un 7754, see infn0ALT 9339. (Contributed by NM, 23-Oct-2004.) Avoid ax-un 7754. (Revised by BTernaryTau, 8-Jan-2025.)
Assertion
Ref Expression
infn0 (ω ≼ 𝐴𝐴 ≠ ∅)

Proof of Theorem infn0
Dummy variable 𝑓 is distinct from all other variables.
StepHypRef Expression
1 brdomi 8998 . 2 (ω ≼ 𝐴 → ∃𝑓 𝑓:ω–1-1𝐴)
2 peano1 7911 . . . . . 6 ∅ ∈ ω
3 f1f1orn 6860 . . . . . . . . 9 (𝑓:ω–1-1𝐴𝑓:ω–1-1-onto→ran 𝑓)
43adantr 480 . . . . . . . 8 ((𝑓:ω–1-1𝐴𝐴 = ∅) → 𝑓:ω–1-1-onto→ran 𝑓)
5 f1f 6805 . . . . . . . . . . 11 (𝑓:ω–1-1𝐴𝑓:ω⟶𝐴)
65frnd 6745 . . . . . . . . . 10 (𝑓:ω–1-1𝐴 → ran 𝑓𝐴)
7 sseq0 4409 . . . . . . . . . 10 ((ran 𝑓𝐴𝐴 = ∅) → ran 𝑓 = ∅)
86, 7sylan 580 . . . . . . . . 9 ((𝑓:ω–1-1𝐴𝐴 = ∅) → ran 𝑓 = ∅)
98f1oeq3d 6846 . . . . . . . 8 ((𝑓:ω–1-1𝐴𝐴 = ∅) → (𝑓:ω–1-1-onto→ran 𝑓𝑓:ω–1-1-onto→∅))
104, 9mpbid 232 . . . . . . 7 ((𝑓:ω–1-1𝐴𝐴 = ∅) → 𝑓:ω–1-1-onto→∅)
11 f1ocnv 6861 . . . . . . 7 (𝑓:ω–1-1-onto→∅ → 𝑓:∅–1-1-onto→ω)
12 noel 4344 . . . . . . . 8 ¬ ∅ ∈ ∅
13 f1o00 6884 . . . . . . . . . 10 (𝑓:∅–1-1-onto→ω ↔ (𝑓 = ∅ ∧ ω = ∅))
1413simprbi 496 . . . . . . . . 9 (𝑓:∅–1-1-onto→ω → ω = ∅)
1514eleq2d 2825 . . . . . . . 8 (𝑓:∅–1-1-onto→ω → (∅ ∈ ω ↔ ∅ ∈ ∅))
1612, 15mtbiri 327 . . . . . . 7 (𝑓:∅–1-1-onto→ω → ¬ ∅ ∈ ω)
1710, 11, 163syl 18 . . . . . 6 ((𝑓:ω–1-1𝐴𝐴 = ∅) → ¬ ∅ ∈ ω)
182, 17mt2 200 . . . . 5 ¬ (𝑓:ω–1-1𝐴𝐴 = ∅)
1918imnani 400 . . . 4 (𝑓:ω–1-1𝐴 → ¬ 𝐴 = ∅)
2019neqned 2945 . . 3 (𝑓:ω–1-1𝐴𝐴 ≠ ∅)
2120exlimiv 1928 . 2 (∃𝑓 𝑓:ω–1-1𝐴𝐴 ≠ ∅)
221, 21syl 17 1 (ω ≼ 𝐴𝐴 ≠ ∅)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wa 395   = wceq 1537  wex 1776  wcel 2106  wne 2938  wss 3963  c0 4339   class class class wbr 5148  ccnv 5688  ran crn 5690  1-1wf1 6560  1-1-ontowf1o 6562  ωcom 7887  cdom 8982
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1792  ax-4 1806  ax-5 1908  ax-6 1965  ax-7 2005  ax-8 2108  ax-9 2116  ax-12 2175  ax-ext 2706  ax-sep 5302  ax-nul 5312  ax-pr 5438
This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3or 1087  df-3an 1088  df-tru 1540  df-fal 1550  df-ex 1777  df-sb 2063  df-mo 2538  df-clab 2713  df-cleq 2727  df-clel 2814  df-ne 2939  df-ral 3060  df-rex 3069  df-rab 3434  df-v 3480  df-dif 3966  df-un 3968  df-in 3970  df-ss 3980  df-pss 3983  df-nul 4340  df-if 4532  df-pw 4607  df-sn 4632  df-pr 4634  df-op 4638  df-uni 4913  df-br 5149  df-opab 5211  df-tr 5266  df-id 5583  df-eprel 5589  df-po 5597  df-so 5598  df-fr 5641  df-we 5643  df-xp 5695  df-rel 5696  df-cnv 5697  df-co 5698  df-dm 5699  df-rn 5700  df-ord 6389  df-on 6390  df-lim 6391  df-fun 6565  df-fn 6566  df-f 6567  df-f1 6568  df-fo 6569  df-f1o 6570  df-om 7888  df-dom 8986
This theorem is referenced by:  infpwfien  10100  infxp  10252  infpss  10254  alephmul  10616  csdfil  23918
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