Theorem oacan 7782

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

Step	Hyp	Ref	Expression
1		oaord 7781	. . . . 5 ⊢ ((𝐵 ∈ On ∧ 𝐶 ∈ On ∧ 𝐴 ∈ On) → (𝐵 ∈ 𝐶 ↔ (𝐴 +𝑜 𝐵) ∈ (𝐴 +𝑜 𝐶)))
2	1	3comr 1119	. . . 4 ⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝐶 ∈ On) → (𝐵 ∈ 𝐶 ↔ (𝐴 +𝑜 𝐵) ∈ (𝐴 +𝑜 𝐶)))
3		oaord 7781	. . . . 5 ⊢ ((𝐶 ∈ On ∧ 𝐵 ∈ On ∧ 𝐴 ∈ On) → (𝐶 ∈ 𝐵 ↔ (𝐴 +𝑜 𝐶) ∈ (𝐴 +𝑜 𝐵)))
4	3	3com13 1118	. . . 4 ⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝐶 ∈ On) → (𝐶 ∈ 𝐵 ↔ (𝐴 +𝑜 𝐶) ∈ (𝐴 +𝑜 𝐵)))
5	2, 4	orbi12d 904	. . 3 ⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝐶 ∈ On) → ((𝐵 ∈ 𝐶 ∨ 𝐶 ∈ 𝐵) ↔ ((𝐴 +𝑜 𝐵) ∈ (𝐴 +𝑜 𝐶) ∨ (𝐴 +𝑜 𝐶) ∈ (𝐴 +𝑜 𝐵))))
6	5	notbid 307	. 2 ⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝐶 ∈ On) → (¬ (𝐵 ∈ 𝐶 ∨ 𝐶 ∈ 𝐵) ↔ ¬ ((𝐴 +𝑜 𝐵) ∈ (𝐴 +𝑜 𝐶) ∨ (𝐴 +𝑜 𝐶) ∈ (𝐴 +𝑜 𝐵))))
7		eloni 5876	. . . 4 ⊢ (𝐵 ∈ On → Ord 𝐵)
8		eloni 5876	. . . 4 ⊢ (𝐶 ∈ On → Ord 𝐶)
9		ordtri3 5902	. . . 4 ⊢ ((Ord 𝐵 ∧ Ord 𝐶) → (𝐵 = 𝐶 ↔ ¬ (𝐵 ∈ 𝐶 ∨ 𝐶 ∈ 𝐵)))
10	7, 8, 9	syl2an 583	. . 3 ⊢ ((𝐵 ∈ On ∧ 𝐶 ∈ On) → (𝐵 = 𝐶 ↔ ¬ (𝐵 ∈ 𝐶 ∨ 𝐶 ∈ 𝐵)))
11	10	3adant1 1124	. 2 ⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝐶 ∈ On) → (𝐵 = 𝐶 ↔ ¬ (𝐵 ∈ 𝐶 ∨ 𝐶 ∈ 𝐵)))
12		oacl 7769	. . . . 5 ⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (𝐴 +𝑜 𝐵) ∈ On)
13		eloni 5876	. . . . 5 ⊢ ((𝐴 +𝑜 𝐵) ∈ On → Ord (𝐴 +𝑜 𝐵))
14	12, 13	syl 17	. . . 4 ⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On) → Ord (𝐴 +𝑜 𝐵))
15		oacl 7769	. . . . 5 ⊢ ((𝐴 ∈ On ∧ 𝐶 ∈ On) → (𝐴 +𝑜 𝐶) ∈ On)
16		eloni 5876	. . . . 5 ⊢ ((𝐴 +𝑜 𝐶) ∈ On → Ord (𝐴 +𝑜 𝐶))
17	15, 16	syl 17	. . . 4 ⊢ ((𝐴 ∈ On ∧ 𝐶 ∈ On) → Ord (𝐴 +𝑜 𝐶))
18		ordtri3 5902	. . . 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))))
19	14, 17, 18	syl2an 583	. . 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))))
20	19	3impdi 1443	. 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))))
21	6, 11, 20	3bitr4rd 301	1 ⊢ ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝐶 ∈ On) → ((𝐴 +𝑜 𝐵) = (𝐴 +𝑜 𝐶) ↔ 𝐵 = 𝐶))

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 196   ∧ wa 382   ∨ wo 836   ∧ w3a 1071   = wceq 1631   ∈ wcel 2145  Ord word 5865  Oncon0 5866  (class class class)co 6793   +_𝑜 coa 7710

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1870  ax-4 1885  ax-5 1991  ax-6 2057  ax-7 2093  ax-8 2147  ax-9 2154  ax-10 2174  ax-11 2190  ax-12 2203  ax-13 2408  ax-ext 2751  ax-rep 4904  ax-sep 4915  ax-nul 4923  ax-pow 4974  ax-pr 5034  ax-un 7096

This theorem depends on definitions:  df-bi 197  df-an 383  df-or 837  df-3or 1072  df-3an 1073  df-tru 1634  df-ex 1853  df-nf 1858  df-sb 2050  df-eu 2622  df-mo 2623  df-clab 2758  df-cleq 2764  df-clel 2767  df-nfc 2902  df-ne 2944  df-ral 3066  df-rex 3067  df-reu 3068  df-rab 3070  df-v 3353  df-sbc 3588  df-csb 3683  df-dif 3726  df-un 3728  df-in 3730  df-ss 3737  df-pss 3739  df-nul 4064  df-if 4226  df-pw 4299  df-sn 4317  df-pr 4319  df-tp 4321  df-op 4323  df-uni 4575  df-iun 4656  df-br 4787  df-opab 4847  df-mpt 4864  df-tr 4887  df-id 5157  df-eprel 5162  df-po 5170  df-so 5171  df-fr 5208  df-we 5210  df-xp 5255  df-rel 5256  df-cnv 5257  df-co 5258  df-dm 5259  df-rn 5260  df-res 5261  df-ima 5262  df-pred 5823  df-ord 5869  df-on 5870  df-lim 5871  df-suc 5872  df-iota 5994  df-fun 6033  df-fn 6034  df-f 6035  df-f1 6036  df-fo 6037  df-f1o 6038  df-fv 6039  df-ov 6796  df-oprab 6797  df-mpt2 6798  df-om 7213  df-wrecs 7559  df-recs 7621  df-rdg 7659  df-oadd 7717

This theorem is referenced by:  oawordeulem  7788