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Theorem onaddscl 28306
Description: The surreal ordinals are closed under addition. (Contributed by Scott Fenton, 22-Aug-2025.)
Assertion
Ref Expression
onaddscl ((𝐴 ∈ Ons𝐵 ∈ Ons) → (𝐴 +s 𝐵) ∈ Ons)

Proof of Theorem onaddscl
Dummy variables 𝑥 𝑦 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 fvex 6935 . . . . 5 ( L ‘𝐴) ∈ V
21abrexex 8005 . . . 4 {𝑥 ∣ ∃𝑦 ∈ ( L ‘𝐴)𝑥 = (𝑦 +s 𝐵)} ∈ V
3 fvex 6935 . . . . 5 ( L ‘𝐵) ∈ V
43abrexex 8005 . . . 4 {𝑥 ∣ ∃𝑦 ∈ ( L ‘𝐵)𝑥 = (𝐴 +s 𝑦)} ∈ V
52, 4unex 7781 . . 3 ({𝑥 ∣ ∃𝑦 ∈ ( L ‘𝐴)𝑥 = (𝑦 +s 𝐵)} ∪ {𝑥 ∣ ∃𝑦 ∈ ( L ‘𝐵)𝑥 = (𝐴 +s 𝑦)}) ∈ V
65a1i 11 . 2 ((𝐴 ∈ Ons𝐵 ∈ Ons) → ({𝑥 ∣ ∃𝑦 ∈ ( L ‘𝐴)𝑥 = (𝑦 +s 𝐵)} ∪ {𝑥 ∣ ∃𝑦 ∈ ( L ‘𝐵)𝑥 = (𝐴 +s 𝑦)}) ∈ V)
7 leftssno 27939 . . . . . . . . 9 ( L ‘𝐴) ⊆ No
87sseli 4004 . . . . . . . 8 (𝑦 ∈ ( L ‘𝐴) → 𝑦 No )
98adantl 481 . . . . . . 7 (((𝐴 ∈ Ons𝐵 ∈ Ons) ∧ 𝑦 ∈ ( L ‘𝐴)) → 𝑦 No )
10 onsno 28298 . . . . . . . 8 (𝐵 ∈ Ons𝐵 No )
1110ad2antlr 726 . . . . . . 7 (((𝐴 ∈ Ons𝐵 ∈ Ons) ∧ 𝑦 ∈ ( L ‘𝐴)) → 𝐵 No )
129, 11addscld 28033 . . . . . 6 (((𝐴 ∈ Ons𝐵 ∈ Ons) ∧ 𝑦 ∈ ( L ‘𝐴)) → (𝑦 +s 𝐵) ∈ No )
13 eleq1 2832 . . . . . 6 (𝑥 = (𝑦 +s 𝐵) → (𝑥 No ↔ (𝑦 +s 𝐵) ∈ No ))
1412, 13syl5ibrcom 247 . . . . 5 (((𝐴 ∈ Ons𝐵 ∈ Ons) ∧ 𝑦 ∈ ( L ‘𝐴)) → (𝑥 = (𝑦 +s 𝐵) → 𝑥 No ))
1514rexlimdva 3161 . . . 4 ((𝐴 ∈ Ons𝐵 ∈ Ons) → (∃𝑦 ∈ ( L ‘𝐴)𝑥 = (𝑦 +s 𝐵) → 𝑥 No ))
1615abssdv 4091 . . 3 ((𝐴 ∈ Ons𝐵 ∈ Ons) → {𝑥 ∣ ∃𝑦 ∈ ( L ‘𝐴)𝑥 = (𝑦 +s 𝐵)} ⊆ No )
17 onsno 28298 . . . . . . . 8 (𝐴 ∈ Ons𝐴 No )
1817ad2antrr 725 . . . . . . 7 (((𝐴 ∈ Ons𝐵 ∈ Ons) ∧ 𝑦 ∈ ( L ‘𝐵)) → 𝐴 No )
19 leftssno 27939 . . . . . . . . 9 ( L ‘𝐵) ⊆ No
2019sseli 4004 . . . . . . . 8 (𝑦 ∈ ( L ‘𝐵) → 𝑦 No )
2120adantl 481 . . . . . . 7 (((𝐴 ∈ Ons𝐵 ∈ Ons) ∧ 𝑦 ∈ ( L ‘𝐵)) → 𝑦 No )
2218, 21addscld 28033 . . . . . 6 (((𝐴 ∈ Ons𝐵 ∈ Ons) ∧ 𝑦 ∈ ( L ‘𝐵)) → (𝐴 +s 𝑦) ∈ No )
23 eleq1 2832 . . . . . 6 (𝑥 = (𝐴 +s 𝑦) → (𝑥 No ↔ (𝐴 +s 𝑦) ∈ No ))
2422, 23syl5ibrcom 247 . . . . 5 (((𝐴 ∈ Ons𝐵 ∈ Ons) ∧ 𝑦 ∈ ( L ‘𝐵)) → (𝑥 = (𝐴 +s 𝑦) → 𝑥 No ))
2524rexlimdva 3161 . . . 4 ((𝐴 ∈ Ons𝐵 ∈ Ons) → (∃𝑦 ∈ ( L ‘𝐵)𝑥 = (𝐴 +s 𝑦) → 𝑥 No ))
2625abssdv 4091 . . 3 ((𝐴 ∈ Ons𝐵 ∈ Ons) → {𝑥 ∣ ∃𝑦 ∈ ( L ‘𝐵)𝑥 = (𝐴 +s 𝑦)} ⊆ No )
2716, 26unssd 4215 . 2 ((𝐴 ∈ Ons𝐵 ∈ Ons) → ({𝑥 ∣ ∃𝑦 ∈ ( L ‘𝐴)𝑥 = (𝑦 +s 𝐵)} ∪ {𝑥 ∣ ∃𝑦 ∈ ( L ‘𝐵)𝑥 = (𝐴 +s 𝑦)}) ⊆ No )
281elpw 4626 . . . . . 6 (( L ‘𝐴) ∈ 𝒫 No ↔ ( L ‘𝐴) ⊆ No )
297, 28mpbir 231 . . . . 5 ( L ‘𝐴) ∈ 𝒫 No
30 nulssgt 27863 . . . . 5 (( L ‘𝐴) ∈ 𝒫 No → ( L ‘𝐴) <<s ∅)
3129, 30mp1i 13 . . . 4 ((𝐴 ∈ Ons𝐵 ∈ Ons) → ( L ‘𝐴) <<s ∅)
323elpw 4626 . . . . . 6 (( L ‘𝐵) ∈ 𝒫 No ↔ ( L ‘𝐵) ⊆ No )
3319, 32mpbir 231 . . . . 5 ( L ‘𝐵) ∈ 𝒫 No
34 nulssgt 27863 . . . . 5 (( L ‘𝐵) ∈ 𝒫 No → ( L ‘𝐵) <<s ∅)
3533, 34mp1i 13 . . . 4 ((𝐴 ∈ Ons𝐵 ∈ Ons) → ( L ‘𝐵) <<s ∅)
36 onscutleft 28305 . . . . 5 (𝐴 ∈ Ons𝐴 = (( L ‘𝐴) |s ∅))
3736adantr 480 . . . 4 ((𝐴 ∈ Ons𝐵 ∈ Ons) → 𝐴 = (( L ‘𝐴) |s ∅))
38 onscutleft 28305 . . . . 5 (𝐵 ∈ Ons𝐵 = (( L ‘𝐵) |s ∅))
3938adantl 481 . . . 4 ((𝐴 ∈ Ons𝐵 ∈ Ons) → 𝐵 = (( L ‘𝐵) |s ∅))
4031, 35, 37, 39addsunif 28055 . . 3 ((𝐴 ∈ Ons𝐵 ∈ Ons) → (𝐴 +s 𝐵) = (({𝑥 ∣ ∃𝑦 ∈ ( L ‘𝐴)𝑥 = (𝑦 +s 𝐵)} ∪ {𝑥 ∣ ∃𝑦 ∈ ( L ‘𝐵)𝑥 = (𝐴 +s 𝑦)}) |s ({𝑥 ∣ ∃𝑦 ∈ ∅ 𝑥 = (𝑦 +s 𝐵)} ∪ {𝑥 ∣ ∃𝑦 ∈ ∅ 𝑥 = (𝐴 +s 𝑦)})))
41 rex0 4383 . . . . . . 7 ¬ ∃𝑦 ∈ ∅ 𝑥 = (𝑦 +s 𝐵)
4241abf 4429 . . . . . 6 {𝑥 ∣ ∃𝑦 ∈ ∅ 𝑥 = (𝑦 +s 𝐵)} = ∅
43 rex0 4383 . . . . . . 7 ¬ ∃𝑦 ∈ ∅ 𝑥 = (𝐴 +s 𝑦)
4443abf 4429 . . . . . 6 {𝑥 ∣ ∃𝑦 ∈ ∅ 𝑥 = (𝐴 +s 𝑦)} = ∅
4542, 44uneq12i 4189 . . . . 5 ({𝑥 ∣ ∃𝑦 ∈ ∅ 𝑥 = (𝑦 +s 𝐵)} ∪ {𝑥 ∣ ∃𝑦 ∈ ∅ 𝑥 = (𝐴 +s 𝑦)}) = (∅ ∪ ∅)
46 un0 4417 . . . . 5 (∅ ∪ ∅) = ∅
4745, 46eqtri 2768 . . . 4 ({𝑥 ∣ ∃𝑦 ∈ ∅ 𝑥 = (𝑦 +s 𝐵)} ∪ {𝑥 ∣ ∃𝑦 ∈ ∅ 𝑥 = (𝐴 +s 𝑦)}) = ∅
4847oveq2i 7461 . . 3 (({𝑥 ∣ ∃𝑦 ∈ ( L ‘𝐴)𝑥 = (𝑦 +s 𝐵)} ∪ {𝑥 ∣ ∃𝑦 ∈ ( L ‘𝐵)𝑥 = (𝐴 +s 𝑦)}) |s ({𝑥 ∣ ∃𝑦 ∈ ∅ 𝑥 = (𝑦 +s 𝐵)} ∪ {𝑥 ∣ ∃𝑦 ∈ ∅ 𝑥 = (𝐴 +s 𝑦)})) = (({𝑥 ∣ ∃𝑦 ∈ ( L ‘𝐴)𝑥 = (𝑦 +s 𝐵)} ∪ {𝑥 ∣ ∃𝑦 ∈ ( L ‘𝐵)𝑥 = (𝐴 +s 𝑦)}) |s ∅)
4940, 48eqtrdi 2796 . 2 ((𝐴 ∈ Ons𝐵 ∈ Ons) → (𝐴 +s 𝐵) = (({𝑥 ∣ ∃𝑦 ∈ ( L ‘𝐴)𝑥 = (𝑦 +s 𝐵)} ∪ {𝑥 ∣ ∃𝑦 ∈ ( L ‘𝐵)𝑥 = (𝐴 +s 𝑦)}) |s ∅))
506, 27, 49elons2d 28302 1 ((𝐴 ∈ Ons𝐵 ∈ Ons) → (𝐴 +s 𝐵) ∈ Ons)
Colors of variables: wff setvar class
Syntax hints:  wi 4  wa 395   = wceq 1537  wcel 2108  {cab 2717  wrex 3076  Vcvv 3488  cun 3974  wss 3976  c0 4352  𝒫 cpw 4622   class class class wbr 5166  cfv 6575  (class class class)co 7450   No csur 27704   <<s csslt 27845   |s cscut 27847   L cleft 27904   +s cadds 28012  Onscons 28294
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1793  ax-4 1807  ax-5 1909  ax-6 1967  ax-7 2007  ax-8 2110  ax-9 2118  ax-10 2141  ax-11 2158  ax-12 2178  ax-ext 2711  ax-rep 5303  ax-sep 5317  ax-nul 5324  ax-pow 5383  ax-pr 5447  ax-un 7772
This theorem depends on definitions:  df-bi 207  df-an 396  df-or 847  df-3or 1088  df-3an 1089  df-tru 1540  df-fal 1550  df-ex 1778  df-nf 1782  df-sb 2065  df-mo 2543  df-eu 2572  df-clab 2718  df-cleq 2732  df-clel 2819  df-nfc 2895  df-ne 2947  df-ral 3068  df-rex 3077  df-rmo 3388  df-reu 3389  df-rab 3444  df-v 3490  df-sbc 3805  df-csb 3922  df-dif 3979  df-un 3981  df-in 3983  df-ss 3993  df-pss 3996  df-nul 4353  df-if 4549  df-pw 4624  df-sn 4649  df-pr 4651  df-tp 4653  df-op 4655  df-ot 4657  df-uni 4932  df-int 4971  df-iun 5017  df-br 5167  df-opab 5229  df-mpt 5250  df-tr 5284  df-id 5593  df-eprel 5599  df-po 5607  df-so 5608  df-fr 5652  df-se 5653  df-we 5654  df-xp 5706  df-rel 5707  df-cnv 5708  df-co 5709  df-dm 5710  df-rn 5711  df-res 5712  df-ima 5713  df-pred 6334  df-ord 6400  df-on 6401  df-suc 6403  df-iota 6527  df-fun 6577  df-fn 6578  df-f 6579  df-f1 6580  df-fo 6581  df-f1o 6582  df-fv 6583  df-riota 7406  df-ov 7453  df-oprab 7454  df-mpo 7455  df-1st 8032  df-2nd 8033  df-frecs 8324  df-wrecs 8355  df-recs 8429  df-1o 8524  df-2o 8525  df-nadd 8724  df-no 27707  df-slt 27708  df-bday 27709  df-sle 27810  df-sslt 27846  df-scut 27848  df-0s 27889  df-made 27906  df-old 27907  df-left 27909  df-right 27910  df-norec2 28002  df-adds 28013  df-ons 28295
This theorem is referenced by:  peano2ons  28308
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