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Theorem ordiso 8365
Description: Order-isomorphic ordinal numbers are equal. (Contributed by Jeff Hankins, 16-Oct-2009.) (Proof shortened by Mario Carneiro, 24-Jun-2015.)
Assertion
Ref Expression
ordiso ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 = 𝐵 ↔ ∃𝑓 𝑓 Isom E , E (𝐴, 𝐵)))
Distinct variable groups:   𝐴,𝑓   𝐵,𝑓

Proof of Theorem ordiso
StepHypRef Expression
1 resiexg 7049 . . . . 5 (𝐴 ∈ On → ( I ↾ 𝐴) ∈ V)
2 isoid 6533 . . . . 5 ( I ↾ 𝐴) Isom E , E (𝐴, 𝐴)
3 isoeq1 6521 . . . . . 6 (𝑓 = ( I ↾ 𝐴) → (𝑓 Isom E , E (𝐴, 𝐴) ↔ ( I ↾ 𝐴) Isom E , E (𝐴, 𝐴)))
43spcegv 3280 . . . . 5 (( I ↾ 𝐴) ∈ V → (( I ↾ 𝐴) Isom E , E (𝐴, 𝐴) → ∃𝑓 𝑓 Isom E , E (𝐴, 𝐴)))
51, 2, 4mpisyl 21 . . . 4 (𝐴 ∈ On → ∃𝑓 𝑓 Isom E , E (𝐴, 𝐴))
65adantr 481 . . 3 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → ∃𝑓 𝑓 Isom E , E (𝐴, 𝐴))
7 isoeq5 6525 . . . 4 (𝐴 = 𝐵 → (𝑓 Isom E , E (𝐴, 𝐴) ↔ 𝑓 Isom E , E (𝐴, 𝐵)))
87exbidv 1847 . . 3 (𝐴 = 𝐵 → (∃𝑓 𝑓 Isom E , E (𝐴, 𝐴) ↔ ∃𝑓 𝑓 Isom E , E (𝐴, 𝐵)))
96, 8syl5ibcom 235 . 2 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 = 𝐵 → ∃𝑓 𝑓 Isom E , E (𝐴, 𝐵)))
10 eloni 5692 . . . 4 (𝐴 ∈ On → Ord 𝐴)
11 eloni 5692 . . . 4 (𝐵 ∈ On → Ord 𝐵)
12 ordiso2 8364 . . . . . 6 ((𝑓 Isom E , E (𝐴, 𝐵) ∧ Ord 𝐴 ∧ Ord 𝐵) → 𝐴 = 𝐵)
13123coml 1269 . . . . 5 ((Ord 𝐴 ∧ Ord 𝐵𝑓 Isom E , E (𝐴, 𝐵)) → 𝐴 = 𝐵)
14133expia 1264 . . . 4 ((Ord 𝐴 ∧ Ord 𝐵) → (𝑓 Isom E , E (𝐴, 𝐵) → 𝐴 = 𝐵))
1510, 11, 14syl2an 494 . . 3 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝑓 Isom E , E (𝐴, 𝐵) → 𝐴 = 𝐵))
1615exlimdv 1858 . 2 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (∃𝑓 𝑓 Isom E , E (𝐴, 𝐵) → 𝐴 = 𝐵))
179, 16impbid 202 1 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 = 𝐵 ↔ ∃𝑓 𝑓 Isom E , E (𝐴, 𝐵)))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 196  wa 384   = wceq 1480  wex 1701  wcel 1987  Vcvv 3186   E cep 4983   I cid 4984  cres 5076  Ord word 5681  Oncon0 5682   Isom wiso 5848
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-sep 4741  ax-nul 4749  ax-pow 4803  ax-pr 4867  ax-un 6902
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-rab 2916  df-v 3188  df-sbc 3418  df-dif 3558  df-un 3560  df-in 3562  df-ss 3569  df-pss 3571  df-nul 3892  df-if 4059  df-pw 4132  df-sn 4149  df-pr 4151  df-tp 4153  df-op 4155  df-uni 4403  df-br 4614  df-opab 4674  df-mpt 4675  df-tr 4713  df-eprel 4985  df-id 4989  df-po 4995  df-so 4996  df-fr 5033  df-we 5035  df-xp 5080  df-rel 5081  df-cnv 5082  df-co 5083  df-dm 5084  df-rn 5085  df-res 5086  df-ima 5087  df-ord 5685  df-on 5686  df-iota 5810  df-fun 5849  df-fn 5850  df-f 5851  df-f1 5852  df-fo 5853  df-f1o 5854  df-fv 5855  df-isom 5856
This theorem is referenced by: (None)
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