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Theorem iscard3 9849
Description: Two ways to express the property of being a cardinal number. (Contributed by NM, 9-Nov-2003.)
Assertion
Ref Expression
iscard3 ((card‘𝐴) = 𝐴𝐴 ∈ (ω ∪ ran ℵ))

Proof of Theorem iscard3
StepHypRef Expression
1 cardon 9702 . . . . . . . . 9 (card‘𝐴) ∈ On
2 eleq1 2826 . . . . . . . . 9 ((card‘𝐴) = 𝐴 → ((card‘𝐴) ∈ On ↔ 𝐴 ∈ On))
31, 2mpbii 232 . . . . . . . 8 ((card‘𝐴) = 𝐴𝐴 ∈ On)
4 eloni 6276 . . . . . . . 8 (𝐴 ∈ On → Ord 𝐴)
53, 4syl 17 . . . . . . 7 ((card‘𝐴) = 𝐴 → Ord 𝐴)
6 ordom 7722 . . . . . . 7 Ord ω
7 ordtri2or 6361 . . . . . . 7 ((Ord 𝐴 ∧ Ord ω) → (𝐴 ∈ ω ∨ ω ⊆ 𝐴))
85, 6, 7sylancl 586 . . . . . 6 ((card‘𝐴) = 𝐴 → (𝐴 ∈ ω ∨ ω ⊆ 𝐴))
98ord 861 . . . . 5 ((card‘𝐴) = 𝐴 → (¬ 𝐴 ∈ ω → ω ⊆ 𝐴))
10 isinfcard 9848 . . . . . . 7 ((ω ⊆ 𝐴 ∧ (card‘𝐴) = 𝐴) ↔ 𝐴 ∈ ran ℵ)
1110biimpi 215 . . . . . 6 ((ω ⊆ 𝐴 ∧ (card‘𝐴) = 𝐴) → 𝐴 ∈ ran ℵ)
1211expcom 414 . . . . 5 ((card‘𝐴) = 𝐴 → (ω ⊆ 𝐴𝐴 ∈ ran ℵ))
139, 12syld 47 . . . 4 ((card‘𝐴) = 𝐴 → (¬ 𝐴 ∈ ω → 𝐴 ∈ ran ℵ))
1413orrd 860 . . 3 ((card‘𝐴) = 𝐴 → (𝐴 ∈ ω ∨ 𝐴 ∈ ran ℵ))
15 cardnn 9721 . . . 4 (𝐴 ∈ ω → (card‘𝐴) = 𝐴)
1610bicomi 223 . . . . 5 (𝐴 ∈ ran ℵ ↔ (ω ⊆ 𝐴 ∧ (card‘𝐴) = 𝐴))
1716simprbi 497 . . . 4 (𝐴 ∈ ran ℵ → (card‘𝐴) = 𝐴)
1815, 17jaoi 854 . . 3 ((𝐴 ∈ ω ∨ 𝐴 ∈ ran ℵ) → (card‘𝐴) = 𝐴)
1914, 18impbii 208 . 2 ((card‘𝐴) = 𝐴 ↔ (𝐴 ∈ ω ∨ 𝐴 ∈ ran ℵ))
20 elun 4083 . 2 (𝐴 ∈ (ω ∪ ran ℵ) ↔ (𝐴 ∈ ω ∨ 𝐴 ∈ ran ℵ))
2119, 20bitr4i 277 1 ((card‘𝐴) = 𝐴𝐴 ∈ (ω ∪ ran ℵ))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wb 205  wa 396  wo 844   = wceq 1539  wcel 2106  cun 3885  wss 3887  ran crn 5590  Ord word 6265  Oncon0 6266  cfv 6433  ωcom 7712  cardccrd 9693  cale 9694
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1798  ax-4 1812  ax-5 1913  ax-6 1971  ax-7 2011  ax-8 2108  ax-9 2116  ax-10 2137  ax-11 2154  ax-12 2171  ax-ext 2709  ax-rep 5209  ax-sep 5223  ax-nul 5230  ax-pow 5288  ax-pr 5352  ax-un 7588  ax-inf2 9399
This theorem depends on definitions:  df-bi 206  df-an 397  df-or 845  df-3or 1087  df-3an 1088  df-tru 1542  df-fal 1552  df-ex 1783  df-nf 1787  df-sb 2068  df-mo 2540  df-eu 2569  df-clab 2716  df-cleq 2730  df-clel 2816  df-nfc 2889  df-ne 2944  df-ral 3069  df-rex 3070  df-rmo 3071  df-reu 3072  df-rab 3073  df-v 3434  df-sbc 3717  df-csb 3833  df-dif 3890  df-un 3892  df-in 3894  df-ss 3904  df-pss 3906  df-nul 4257  df-if 4460  df-pw 4535  df-sn 4562  df-pr 4564  df-op 4568  df-uni 4840  df-int 4880  df-iun 4926  df-br 5075  df-opab 5137  df-mpt 5158  df-tr 5192  df-id 5489  df-eprel 5495  df-po 5503  df-so 5504  df-fr 5544  df-se 5545  df-we 5546  df-xp 5595  df-rel 5596  df-cnv 5597  df-co 5598  df-dm 5599  df-rn 5600  df-res 5601  df-ima 5602  df-pred 6202  df-ord 6269  df-on 6270  df-lim 6271  df-suc 6272  df-iota 6391  df-fun 6435  df-fn 6436  df-f 6437  df-f1 6438  df-fo 6439  df-f1o 6440  df-fv 6441  df-isom 6442  df-riota 7232  df-ov 7278  df-om 7713  df-2nd 7832  df-frecs 8097  df-wrecs 8128  df-recs 8202  df-rdg 8241  df-1o 8297  df-er 8498  df-en 8734  df-dom 8735  df-sdom 8736  df-fin 8737  df-oi 9269  df-har 9316  df-card 9697  df-aleph 9698
This theorem is referenced by:  cardnum  9850  carduniima  9852  cardinfima  9853  cfpwsdom  10340  gch2  10431
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