Theorem oacl 3138

Description: Closure law for ordinal addition. Proposition 8.2 of [TakeutiZaring] p. 57.

Assertion

Ref	Expression
oacl	⊢ ((A ∈ On ∧ B ∈ On) → (A +o B) ∈ On)

Proof of Theorem oacl

Step	Hyp	Ref	Expression
1		opreq2 3007	. . . . 5 ⊢ (x = ∅ → (A +o x) = (A +o ∅))
2	1	eleq1d 1155	. . . 4 ⊢ (x = ∅ → ((A +o x) ∈ On ↔ (A +o ∅) ∈ On))
3		opreq2 3007	. . . . 5 ⊢ (x = y → (A +o x) = (A +o y))
4	3	eleq1d 1155	. . . 4 ⊢ (x = y → ((A +o x) ∈ On ↔ (A +o y) ∈ On))
5		opreq2 3007	. . . . 5 ⊢ (x = suc y → (A +o x) = (A +o suc y))
6	5	eleq1d 1155	. . . 4 ⊢ (x = suc y → ((A +o x) ∈ On ↔ (A +o suc y) ∈ On))
7		opreq2 3007	. . . . 5 ⊢ (x = B → (A +o x) = (A +o B))
8	7	eleq1d 1155	. . . 4 ⊢ (x = B → ((A +o x) ∈ On ↔ (A +o B) ∈ On))
9		oa0 3124	. . . . . 6 ⊢ (A ∈ On → (A +o ∅) = A)
10	9	eleq1d 1155	. . . . 5 ⊢ (A ∈ On → ((A +o ∅) ∈ On ↔ A ∈ On))
11	10	ibir 450	. . . 4 ⊢ (A ∈ On → (A +o ∅) ∈ On)
12		oasuc 3131	. . . . . . . 8 ⊢ ((A ∈ On ∧ y ∈ On) → (A +o suc y) = suc (A +o y))
13	12	eleq1d 1155	. . . . . . 7 ⊢ ((A ∈ On ∧ y ∈ On) → ((A +o suc y) ∈ On ↔ suc (A +o y) ∈ On))
14		suceloni 2314	. . . . . . 7 ⊢ ((A +o y) ∈ On → suc (A +o y) ∈ On)
15	13, 14	syl5bir 184	. . . . . 6 ⊢ ((A ∈ On ∧ y ∈ On) → ((A +o y) ∈ On → (A +o suc y) ∈ On))
16	15	exp 291	. . . . 5 ⊢ (A ∈ On → (y ∈ On → ((A +o y) ∈ On → (A +o suc y) ∈ On)))
17	16	com12 13	. . . 4 ⊢ (y ∈ On → (A ∈ On → ((A +o y) ∈ On → (A +o suc y) ∈ On)))
18		visset 1350	. . . . . . . . 9 ⊢ x ∈ V
19		oalim 3135	. . . . . . . . 9 ⊢ ((A ∈ On ∧ (x ∈ V ∧ Lim x)) → (A +o x) = ∪y ∈ x (A +o y))
20	18, 19	mpan21 531	. . . . . . . 8 ⊢ ((A ∈ On ∧ Lim x) → (A +o x) = ∪y ∈ x (A +o y))
21	20	eleq1d 1155	. . . . . . 7 ⊢ ((A ∈ On ∧ Lim x) → ((A +o x) ∈ On ↔ ∪y ∈ x (A +o y) ∈ On))
22		oprex 3018	. . . . . . . 8 ⊢ (A +o y) ∈ V
23	18, 22	iunon 2947	. . . . . . 7 ⊢ (∀y ∈ x (A +o y) ∈ On → ∪y ∈ x (A +o y) ∈ On)
24	21, 23	syl5bir 184	. . . . . 6 ⊢ ((A ∈ On ∧ Lim x) → (∀y ∈ x (A +o y) ∈ On → (A +o x) ∈ On))
25	24	exp 291	. . . . 5 ⊢ (A ∈ On → (Lim x → (∀y ∈ x (A +o y) ∈ On → (A +o x) ∈ On)))
26	25	com12 13	. . . 4 ⊢ (Lim x → (A ∈ On → (∀y ∈ x (A +o y) ∈ On → (A +o x) ∈ On)))
27	2, 4, 6, 8, 11, 17, 26	tfinds3 2406	. . 3 ⊢ (B ∈ On → (A ∈ On → (A +o B) ∈ On))
28	27	com12 13	. 2 ⊢ (A ∈ On → (B ∈ On → (A +o B) ∈ On))
29	28	imp 277	1 ⊢ ((A ∈ On ∧ B ∈ On) → (A +o B) ∈ On)

Syntax hints:   → wi 2   ∧ wa 196   = weq 797   = wceq 1091   ∈ wcel 1092  ∀wral 1201  Vcvv 1348  ∅c0 1707  ∪ciun 1994  Oncon0 2199  Lim wlim 2200  suc csuc 2201  (class class class)co 3001   +_o coa 3101

This theorem is referenced by:  omcl 3139  oaord 3149  oacan 3150  oaword 3151  oawordri 3152  oawordeulem 3156  oalimcl 3162  oaass 3163

This theorem was proved from axioms:  ax-1 3  ax-2 4  ax-3 5  ax-mp 6  ax-4 673  ax-5 674  ax-6 675  ax-7 676  ax-gen 677  ax-8 798  ax-9 799  ax-10 800  ax-11 801  ax-12 802  ax-13 804  ax-14 805  ax-16 922  ax-17 925  ax-ext 1074  ax-rep 1075  ax-un 1076  ax-pow 1077

This theorem depends on definitions:  df-bi 128  df-or 197  df-an 198  df-3or 582  df-3an 583  df-ex 679  df-sb 853  df-eu 1009  df-mo 1010  df-clab 1093  df-cleq 1097  df-clel 1099  df-ral 1205  df-rex 1206  df-rab 1208  df-v 1349  df-sbc 1441  df-dif 1489  df-un 1490  df-in 1491  df-ss 1492  df-nul 1708  df-if 1777  df-pw 1799  df-sn 1811  df-pr 1812  df-tp 1814  df-op 1815  df-uni 1920  df-iun 1996  df-tr 2042  df-br 2063  df-opab 2098  df-eprel 2122  df-id 2125  df-po 2128  df-so 2138  df-fr 2169  df-we 2186  df-ord 2202  df-on 2203  df-lim 2204  df-suc 2205  df-xp 2424  df-rel 2425  df-cnv 2426  df-co 2427  df-dm 2428  df-rn 2429  df-res 2430  df-ima 2431  df-fun 2432  df-fn 2433  df-fv 2438  df-rdg 2970  df-opr 3003  df-oprab 3004  df-oadd 3106

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