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Theorem ordiso 9554
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 7935 . . . . 5 (𝐴 ∈ On → ( I ↾ 𝐴) ∈ V)
2 isoid 7349 . . . . 5 ( I ↾ 𝐴) Isom E , E (𝐴, 𝐴)
3 isoeq1 7337 . . . . . 6 (𝑓 = ( I ↾ 𝐴) → (𝑓 Isom E , E (𝐴, 𝐴) ↔ ( I ↾ 𝐴) Isom E , E (𝐴, 𝐴)))
43spcegv 3597 . . . . 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 480 . . 3 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → ∃𝑓 𝑓 Isom E , E (𝐴, 𝐴))
7 isoeq5 7341 . . . 4 (𝐴 = 𝐵 → (𝑓 Isom E , E (𝐴, 𝐴) ↔ 𝑓 Isom E , E (𝐴, 𝐵)))
87exbidv 1919 . . 3 (𝐴 = 𝐵 → (∃𝑓 𝑓 Isom E , E (𝐴, 𝐴) ↔ ∃𝑓 𝑓 Isom E , E (𝐴, 𝐵)))
96, 8syl5ibcom 245 . 2 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 = 𝐵 → ∃𝑓 𝑓 Isom E , E (𝐴, 𝐵)))
10 eloni 6396 . . . 4 (𝐴 ∈ On → Ord 𝐴)
11 eloni 6396 . . . 4 (𝐵 ∈ On → Ord 𝐵)
12 ordiso2 9553 . . . . . 6 ((𝑓 Isom E , E (𝐴, 𝐵) ∧ Ord 𝐴 ∧ Ord 𝐵) → 𝐴 = 𝐵)
13123coml 1126 . . . . 5 ((Ord 𝐴 ∧ Ord 𝐵𝑓 Isom E , E (𝐴, 𝐵)) → 𝐴 = 𝐵)
14133expia 1120 . . . 4 ((Ord 𝐴 ∧ Ord 𝐵) → (𝑓 Isom E , E (𝐴, 𝐵) → 𝐴 = 𝐵))
1510, 11, 14syl2an 596 . . 3 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝑓 Isom E , E (𝐴, 𝐵) → 𝐴 = 𝐵))
1615exlimdv 1931 . 2 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (∃𝑓 𝑓 Isom E , E (𝐴, 𝐵) → 𝐴 = 𝐵))
179, 16impbid 212 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 206  wa 395   = wceq 1537  wex 1776  wcel 2106  Vcvv 3478   I cid 5582   E cep 5588  cres 5691  Ord word 6385  Oncon0 6386   Isom wiso 6564
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-10 2139  ax-11 2155  ax-12 2175  ax-ext 2706  ax-sep 5302  ax-nul 5312  ax-pow 5371  ax-pr 5438  ax-un 7754
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-nf 1781  df-sb 2063  df-mo 2538  df-eu 2567  df-clab 2713  df-cleq 2727  df-clel 2814  df-nfc 2890  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-mpt 5232  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-res 5701  df-ima 5702  df-ord 6389  df-on 6390  df-iota 6516  df-fun 6565  df-fn 6566  df-f 6567  df-f1 6568  df-fo 6569  df-f1o 6570  df-fv 6571  df-isom 6572
This theorem is referenced by: (None)
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