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Theorem oacan 8170
Description: Left cancellation law for ordinal addition. Corollary 8.5 of [TakeutiZaring] p. 58. (Contributed by NM, 5-Dec-2004.)
Assertion
Ref Expression
oacan ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝐶 ∈ On) → ((𝐴 +o 𝐵) = (𝐴 +o 𝐶) ↔ 𝐵 = 𝐶))

Proof of Theorem oacan
StepHypRef Expression
1 oaord 8169 . . . . 5 ((𝐵 ∈ On ∧ 𝐶 ∈ On ∧ 𝐴 ∈ On) → (𝐵𝐶 ↔ (𝐴 +o 𝐵) ∈ (𝐴 +o 𝐶)))
213comr 1122 . . . 4 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝐶 ∈ On) → (𝐵𝐶 ↔ (𝐴 +o 𝐵) ∈ (𝐴 +o 𝐶)))
3 oaord 8169 . . . . 5 ((𝐶 ∈ On ∧ 𝐵 ∈ On ∧ 𝐴 ∈ On) → (𝐶𝐵 ↔ (𝐴 +o 𝐶) ∈ (𝐴 +o 𝐵)))
433com13 1121 . . . 4 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝐶 ∈ On) → (𝐶𝐵 ↔ (𝐴 +o 𝐶) ∈ (𝐴 +o 𝐵)))
52, 4orbi12d 916 . . 3 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝐶 ∈ On) → ((𝐵𝐶𝐶𝐵) ↔ ((𝐴 +o 𝐵) ∈ (𝐴 +o 𝐶) ∨ (𝐴 +o 𝐶) ∈ (𝐴 +o 𝐵))))
65notbid 321 . 2 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝐶 ∈ On) → (¬ (𝐵𝐶𝐶𝐵) ↔ ¬ ((𝐴 +o 𝐵) ∈ (𝐴 +o 𝐶) ∨ (𝐴 +o 𝐶) ∈ (𝐴 +o 𝐵))))
7 eloni 6188 . . . 4 (𝐵 ∈ On → Ord 𝐵)
8 eloni 6188 . . . 4 (𝐶 ∈ On → Ord 𝐶)
9 ordtri3 6214 . . . 4 ((Ord 𝐵 ∧ Ord 𝐶) → (𝐵 = 𝐶 ↔ ¬ (𝐵𝐶𝐶𝐵)))
107, 8, 9syl2an 598 . . 3 ((𝐵 ∈ On ∧ 𝐶 ∈ On) → (𝐵 = 𝐶 ↔ ¬ (𝐵𝐶𝐶𝐵)))
11103adant1 1127 . 2 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝐶 ∈ On) → (𝐵 = 𝐶 ↔ ¬ (𝐵𝐶𝐶𝐵)))
12 oacl 8156 . . . . 5 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 +o 𝐵) ∈ On)
13 eloni 6188 . . . . 5 ((𝐴 +o 𝐵) ∈ On → Ord (𝐴 +o 𝐵))
1412, 13syl 17 . . . 4 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → Ord (𝐴 +o 𝐵))
15 oacl 8156 . . . . 5 ((𝐴 ∈ On ∧ 𝐶 ∈ On) → (𝐴 +o 𝐶) ∈ On)
16 eloni 6188 . . . . 5 ((𝐴 +o 𝐶) ∈ On → Ord (𝐴 +o 𝐶))
1715, 16syl 17 . . . 4 ((𝐴 ∈ On ∧ 𝐶 ∈ On) → Ord (𝐴 +o 𝐶))
18 ordtri3 6214 . . . 4 ((Ord (𝐴 +o 𝐵) ∧ Ord (𝐴 +o 𝐶)) → ((𝐴 +o 𝐵) = (𝐴 +o 𝐶) ↔ ¬ ((𝐴 +o 𝐵) ∈ (𝐴 +o 𝐶) ∨ (𝐴 +o 𝐶) ∈ (𝐴 +o 𝐵))))
1914, 17, 18syl2an 598 . . 3 (((𝐴 ∈ On ∧ 𝐵 ∈ On) ∧ (𝐴 ∈ On ∧ 𝐶 ∈ On)) → ((𝐴 +o 𝐵) = (𝐴 +o 𝐶) ↔ ¬ ((𝐴 +o 𝐵) ∈ (𝐴 +o 𝐶) ∨ (𝐴 +o 𝐶) ∈ (𝐴 +o 𝐵))))
20193impdi 1347 . 2 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝐶 ∈ On) → ((𝐴 +o 𝐵) = (𝐴 +o 𝐶) ↔ ¬ ((𝐴 +o 𝐵) ∈ (𝐴 +o 𝐶) ∨ (𝐴 +o 𝐶) ∈ (𝐴 +o 𝐵))))
216, 11, 203bitr4rd 315 1 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝐶 ∈ On) → ((𝐴 +o 𝐵) = (𝐴 +o 𝐶) ↔ 𝐵 = 𝐶))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wb 209  wa 399  wo 844  w3a 1084   = wceq 1538  wcel 2115  Ord word 6177  Oncon0 6178  (class class class)co 7149   +o coa 8095
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1912  ax-6 1971  ax-7 2016  ax-8 2117  ax-9 2125  ax-10 2146  ax-11 2162  ax-12 2179  ax-ext 2796  ax-rep 5176  ax-sep 5189  ax-nul 5196  ax-pow 5253  ax-pr 5317  ax-un 7455
This theorem depends on definitions:  df-bi 210  df-an 400  df-or 845  df-3or 1085  df-3an 1086  df-tru 1541  df-ex 1782  df-nf 1786  df-sb 2071  df-mo 2624  df-eu 2655  df-clab 2803  df-cleq 2817  df-clel 2896  df-nfc 2964  df-ne 3015  df-ral 3138  df-rex 3139  df-reu 3140  df-rab 3142  df-v 3482  df-sbc 3759  df-csb 3867  df-dif 3922  df-un 3924  df-in 3926  df-ss 3936  df-pss 3938  df-nul 4277  df-if 4451  df-pw 4524  df-sn 4551  df-pr 4553  df-tp 4555  df-op 4557  df-uni 4825  df-iun 4907  df-br 5053  df-opab 5115  df-mpt 5133  df-tr 5159  df-id 5447  df-eprel 5452  df-po 5461  df-so 5462  df-fr 5501  df-we 5503  df-xp 5548  df-rel 5549  df-cnv 5550  df-co 5551  df-dm 5552  df-rn 5553  df-res 5554  df-ima 5555  df-pred 6135  df-ord 6181  df-on 6182  df-lim 6183  df-suc 6184  df-iota 6302  df-fun 6345  df-fn 6346  df-f 6347  df-f1 6348  df-fo 6349  df-f1o 6350  df-fv 6351  df-ov 7152  df-oprab 7153  df-mpo 7154  df-om 7575  df-wrecs 7943  df-recs 8004  df-rdg 8042  df-oadd 8102
This theorem is referenced by:  oawordeulem  8176
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