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Theorem oaordex 7683
 Description: Existence theorem for ordering of ordinal sum. Similar to Proposition 4.34(f) of [Mendelson] p. 266 and its converse. (Contributed by NM, 12-Dec-2004.)
Assertion
Ref Expression
oaordex ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴𝐵 ↔ ∃𝑥 ∈ On (∅ ∈ 𝑥 ∧ (𝐴 +𝑜 𝑥) = 𝐵)))
Distinct variable groups:   𝑥,𝐴   𝑥,𝐵

Proof of Theorem oaordex
StepHypRef Expression
1 onelss 5804 . . . . 5 (𝐵 ∈ On → (𝐴𝐵𝐴𝐵))
21adantl 481 . . . 4 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴𝐵𝐴𝐵))
3 oawordex 7682 . . . 4 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴𝐵 ↔ ∃𝑥 ∈ On (𝐴 +𝑜 𝑥) = 𝐵))
42, 3sylibd 229 . . 3 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴𝐵 → ∃𝑥 ∈ On (𝐴 +𝑜 𝑥) = 𝐵))
5 oaord1 7676 . . . . . . . . . . . . 13 ((𝐴 ∈ On ∧ 𝑥 ∈ On) → (∅ ∈ 𝑥𝐴 ∈ (𝐴 +𝑜 𝑥)))
6 eleq2 2719 . . . . . . . . . . . . 13 ((𝐴 +𝑜 𝑥) = 𝐵 → (𝐴 ∈ (𝐴 +𝑜 𝑥) ↔ 𝐴𝐵))
75, 6sylan9bb 736 . . . . . . . . . . . 12 (((𝐴 ∈ On ∧ 𝑥 ∈ On) ∧ (𝐴 +𝑜 𝑥) = 𝐵) → (∅ ∈ 𝑥𝐴𝐵))
87biimprcd 240 . . . . . . . . . . 11 (𝐴𝐵 → (((𝐴 ∈ On ∧ 𝑥 ∈ On) ∧ (𝐴 +𝑜 𝑥) = 𝐵) → ∅ ∈ 𝑥))
98exp4c 635 . . . . . . . . . 10 (𝐴𝐵 → (𝐴 ∈ On → (𝑥 ∈ On → ((𝐴 +𝑜 𝑥) = 𝐵 → ∅ ∈ 𝑥))))
109com12 32 . . . . . . . . 9 (𝐴 ∈ On → (𝐴𝐵 → (𝑥 ∈ On → ((𝐴 +𝑜 𝑥) = 𝐵 → ∅ ∈ 𝑥))))
1110imp4b 612 . . . . . . . 8 ((𝐴 ∈ On ∧ 𝐴𝐵) → ((𝑥 ∈ On ∧ (𝐴 +𝑜 𝑥) = 𝐵) → ∅ ∈ 𝑥))
12 simpr 476 . . . . . . . . 9 ((𝑥 ∈ On ∧ (𝐴 +𝑜 𝑥) = 𝐵) → (𝐴 +𝑜 𝑥) = 𝐵)
1312a1i 11 . . . . . . . 8 ((𝐴 ∈ On ∧ 𝐴𝐵) → ((𝑥 ∈ On ∧ (𝐴 +𝑜 𝑥) = 𝐵) → (𝐴 +𝑜 𝑥) = 𝐵))
1411, 13jcad 554 . . . . . . 7 ((𝐴 ∈ On ∧ 𝐴𝐵) → ((𝑥 ∈ On ∧ (𝐴 +𝑜 𝑥) = 𝐵) → (∅ ∈ 𝑥 ∧ (𝐴 +𝑜 𝑥) = 𝐵)))
1514expd 451 . . . . . 6 ((𝐴 ∈ On ∧ 𝐴𝐵) → (𝑥 ∈ On → ((𝐴 +𝑜 𝑥) = 𝐵 → (∅ ∈ 𝑥 ∧ (𝐴 +𝑜 𝑥) = 𝐵))))
1615reximdvai 3044 . . . . 5 ((𝐴 ∈ On ∧ 𝐴𝐵) → (∃𝑥 ∈ On (𝐴 +𝑜 𝑥) = 𝐵 → ∃𝑥 ∈ On (∅ ∈ 𝑥 ∧ (𝐴 +𝑜 𝑥) = 𝐵)))
1716ex 449 . . . 4 (𝐴 ∈ On → (𝐴𝐵 → (∃𝑥 ∈ On (𝐴 +𝑜 𝑥) = 𝐵 → ∃𝑥 ∈ On (∅ ∈ 𝑥 ∧ (𝐴 +𝑜 𝑥) = 𝐵))))
1817adantr 480 . . 3 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴𝐵 → (∃𝑥 ∈ On (𝐴 +𝑜 𝑥) = 𝐵 → ∃𝑥 ∈ On (∅ ∈ 𝑥 ∧ (𝐴 +𝑜 𝑥) = 𝐵))))
194, 18mpdd 43 . 2 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴𝐵 → ∃𝑥 ∈ On (∅ ∈ 𝑥 ∧ (𝐴 +𝑜 𝑥) = 𝐵)))
207biimpd 219 . . . . . . 7 (((𝐴 ∈ On ∧ 𝑥 ∈ On) ∧ (𝐴 +𝑜 𝑥) = 𝐵) → (∅ ∈ 𝑥𝐴𝐵))
2120exp31 629 . . . . . 6 (𝐴 ∈ On → (𝑥 ∈ On → ((𝐴 +𝑜 𝑥) = 𝐵 → (∅ ∈ 𝑥𝐴𝐵))))
2221com34 91 . . . . 5 (𝐴 ∈ On → (𝑥 ∈ On → (∅ ∈ 𝑥 → ((𝐴 +𝑜 𝑥) = 𝐵𝐴𝐵))))
2322imp4a 613 . . . 4 (𝐴 ∈ On → (𝑥 ∈ On → ((∅ ∈ 𝑥 ∧ (𝐴 +𝑜 𝑥) = 𝐵) → 𝐴𝐵)))
2423rexlimdv 3059 . . 3 (𝐴 ∈ On → (∃𝑥 ∈ On (∅ ∈ 𝑥 ∧ (𝐴 +𝑜 𝑥) = 𝐵) → 𝐴𝐵))
2524adantr 480 . 2 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (∃𝑥 ∈ On (∅ ∈ 𝑥 ∧ (𝐴 +𝑜 𝑥) = 𝐵) → 𝐴𝐵))
2619, 25impbid 202 1 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴𝐵 ↔ ∃𝑥 ∈ On (∅ ∈ 𝑥 ∧ (𝐴 +𝑜 𝑥) = 𝐵)))
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ↔ wb 196   ∧ wa 383   = wceq 1523   ∈ wcel 2030  ∃wrex 2942   ⊆ wss 3607  ∅c0 3948  Oncon0 5761  (class class class)co 6690   +𝑜 coa 7602 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1762  ax-4 1777  ax-5 1879  ax-6 1945  ax-7 1981  ax-8 2032  ax-9 2039  ax-10 2059  ax-11 2074  ax-12 2087  ax-13 2282  ax-ext 2631  ax-rep 4804  ax-sep 4814  ax-nul 4822  ax-pow 4873  ax-pr 4936  ax-un 6991 This theorem depends on definitions:  df-bi 197  df-or 384  df-an 385  df-3or 1055  df-3an 1056  df-tru 1526  df-ex 1745  df-nf 1750  df-sb 1938  df-eu 2502  df-mo 2503  df-clab 2638  df-cleq 2644  df-clel 2647  df-nfc 2782  df-ne 2824  df-ral 2946  df-rex 2947  df-reu 2948  df-rmo 2949  df-rab 2950  df-v 3233  df-sbc 3469  df-csb 3567  df-dif 3610  df-un 3612  df-in 3614  df-ss 3621  df-pss 3623  df-nul 3949  df-if 4120  df-pw 4193  df-sn 4211  df-pr 4213  df-tp 4215  df-op 4217  df-uni 4469  df-int 4508  df-iun 4554  df-br 4686  df-opab 4746  df-mpt 4763  df-tr 4786  df-id 5053  df-eprel 5058  df-po 5064  df-so 5065  df-fr 5102  df-we 5104  df-xp 5149  df-rel 5150  df-cnv 5151  df-co 5152  df-dm 5153  df-rn 5154  df-res 5155  df-ima 5156  df-pred 5718  df-ord 5764  df-on 5765  df-lim 5766  df-suc 5767  df-iota 5889  df-fun 5928  df-fn 5929  df-f 5930  df-f1 5931  df-fo 5932  df-f1o 5933  df-fv 5934  df-ov 6693  df-oprab 6694  df-mpt2 6695  df-om 7108  df-wrecs 7452  df-recs 7513  df-rdg 7551  df-oadd 7609 This theorem is referenced by: (None)
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