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 Description: There is no identity element for addition on positive integers. (Contributed by NM, 28-Nov-1995.) (New usage is discouraged.)
Assertion
Ref Expression
addnidpi (𝐴N → ¬ (𝐴 +N 𝐵) = 𝐴)

StepHypRef Expression
1 pinn 9892 . . . . 5 (𝐴N𝐴 ∈ ω)
2 elni2 9891 . . . . . 6 (𝐵N ↔ (𝐵 ∈ ω ∧ ∅ ∈ 𝐵))
3 nnaordi 7867 . . . . . . . . 9 ((𝐵 ∈ ω ∧ 𝐴 ∈ ω) → (∅ ∈ 𝐵 → (𝐴 +𝑜 ∅) ∈ (𝐴 +𝑜 𝐵)))
4 nna0 7853 . . . . . . . . . . . 12 (𝐴 ∈ ω → (𝐴 +𝑜 ∅) = 𝐴)
54eleq1d 2824 . . . . . . . . . . 11 (𝐴 ∈ ω → ((𝐴 +𝑜 ∅) ∈ (𝐴 +𝑜 𝐵) ↔ 𝐴 ∈ (𝐴 +𝑜 𝐵)))
6 nnord 7238 . . . . . . . . . . . . . 14 (𝐴 ∈ ω → Ord 𝐴)
7 ordirr 5902 . . . . . . . . . . . . . 14 (Ord 𝐴 → ¬ 𝐴𝐴)
86, 7syl 17 . . . . . . . . . . . . 13 (𝐴 ∈ ω → ¬ 𝐴𝐴)
9 eleq2 2828 . . . . . . . . . . . . . 14 ((𝐴 +𝑜 𝐵) = 𝐴 → (𝐴 ∈ (𝐴 +𝑜 𝐵) ↔ 𝐴𝐴))
109notbid 307 . . . . . . . . . . . . 13 ((𝐴 +𝑜 𝐵) = 𝐴 → (¬ 𝐴 ∈ (𝐴 +𝑜 𝐵) ↔ ¬ 𝐴𝐴))
118, 10syl5ibrcom 237 . . . . . . . . . . . 12 (𝐴 ∈ ω → ((𝐴 +𝑜 𝐵) = 𝐴 → ¬ 𝐴 ∈ (𝐴 +𝑜 𝐵)))
1211con2d 129 . . . . . . . . . . 11 (𝐴 ∈ ω → (𝐴 ∈ (𝐴 +𝑜 𝐵) → ¬ (𝐴 +𝑜 𝐵) = 𝐴))
135, 12sylbid 230 . . . . . . . . . 10 (𝐴 ∈ ω → ((𝐴 +𝑜 ∅) ∈ (𝐴 +𝑜 𝐵) → ¬ (𝐴 +𝑜 𝐵) = 𝐴))
1413adantl 473 . . . . . . . . 9 ((𝐵 ∈ ω ∧ 𝐴 ∈ ω) → ((𝐴 +𝑜 ∅) ∈ (𝐴 +𝑜 𝐵) → ¬ (𝐴 +𝑜 𝐵) = 𝐴))
153, 14syld 47 . . . . . . . 8 ((𝐵 ∈ ω ∧ 𝐴 ∈ ω) → (∅ ∈ 𝐵 → ¬ (𝐴 +𝑜 𝐵) = 𝐴))
1615expcom 450 . . . . . . 7 (𝐴 ∈ ω → (𝐵 ∈ ω → (∅ ∈ 𝐵 → ¬ (𝐴 +𝑜 𝐵) = 𝐴)))
1716imp32 448 . . . . . 6 ((𝐴 ∈ ω ∧ (𝐵 ∈ ω ∧ ∅ ∈ 𝐵)) → ¬ (𝐴 +𝑜 𝐵) = 𝐴)
182, 17sylan2b 493 . . . . 5 ((𝐴 ∈ ω ∧ 𝐵N) → ¬ (𝐴 +𝑜 𝐵) = 𝐴)
191, 18sylan 489 . . . 4 ((𝐴N𝐵N) → ¬ (𝐴 +𝑜 𝐵) = 𝐴)
20 addpiord 9898 . . . . 5 ((𝐴N𝐵N) → (𝐴 +N 𝐵) = (𝐴 +𝑜 𝐵))
2120eqeq1d 2762 . . . 4 ((𝐴N𝐵N) → ((𝐴 +N 𝐵) = 𝐴 ↔ (𝐴 +𝑜 𝐵) = 𝐴))
2219, 21mtbird 314 . . 3 ((𝐴N𝐵N) → ¬ (𝐴 +N 𝐵) = 𝐴)
2322a1d 25 . 2 ((𝐴N𝐵N) → (𝐴N → ¬ (𝐴 +N 𝐵) = 𝐴))
24 dmaddpi 9904 . . . . . 6 dom +N = (N × N)
2524ndmov 6983 . . . . 5 (¬ (𝐴N𝐵N) → (𝐴 +N 𝐵) = ∅)
2625eqeq1d 2762 . . . 4 (¬ (𝐴N𝐵N) → ((𝐴 +N 𝐵) = 𝐴 ↔ ∅ = 𝐴))
27 0npi 9896 . . . . 5 ¬ ∅ ∈ N
28 eleq1 2827 . . . . 5 (∅ = 𝐴 → (∅ ∈ N𝐴N))
2927, 28mtbii 315 . . . 4 (∅ = 𝐴 → ¬ 𝐴N)
3026, 29syl6bi 243 . . 3 (¬ (𝐴N𝐵N) → ((𝐴 +N 𝐵) = 𝐴 → ¬ 𝐴N))
3130con2d 129 . 2 (¬ (𝐴N𝐵N) → (𝐴N → ¬ (𝐴 +N 𝐵) = 𝐴))
3223, 31pm2.61i 176 1 (𝐴N → ¬ (𝐴 +N 𝐵) = 𝐴)
 Colors of variables: wff setvar class Syntax hints:  ¬ wn 3   → wi 4   ∧ wa 383   = wceq 1632   ∈ wcel 2139  ∅c0 4058  Ord word 5883  (class class class)co 6813  ωcom 7230   +𝑜 coa 7726  Ncnpi 9858   +N cpli 9859 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1871  ax-4 1886  ax-5 1988  ax-6 2054  ax-7 2090  ax-8 2141  ax-9 2148  ax-10 2168  ax-11 2183  ax-12 2196  ax-13 2391  ax-ext 2740  ax-sep 4933  ax-nul 4941  ax-pow 4992  ax-pr 5055  ax-un 7114 This theorem depends on definitions:  df-bi 197  df-or 384  df-an 385  df-3or 1073  df-3an 1074  df-tru 1635  df-ex 1854  df-nf 1859  df-sb 2047  df-eu 2611  df-mo 2612  df-clab 2747  df-cleq 2753  df-clel 2756  df-nfc 2891  df-ne 2933  df-ral 3055  df-rex 3056  df-reu 3057  df-rab 3059  df-v 3342  df-sbc 3577  df-csb 3675  df-dif 3718  df-un 3720  df-in 3722  df-ss 3729  df-pss 3731  df-nul 4059  df-if 4231  df-pw 4304  df-sn 4322  df-pr 4324  df-tp 4326  df-op 4328  df-uni 4589  df-iun 4674  df-br 4805  df-opab 4865  df-mpt 4882  df-tr 4905  df-id 5174  df-eprel 5179  df-po 5187  df-so 5188  df-fr 5225  df-we 5227  df-xp 5272  df-rel 5273  df-cnv 5274  df-co 5275  df-dm 5276  df-rn 5277  df-res 5278  df-ima 5279  df-pred 5841  df-ord 5887  df-on 5888  df-lim 5889  df-suc 5890  df-iota 6012  df-fun 6051  df-fn 6052  df-f 6053  df-f1 6054  df-fo 6055  df-f1o 6056  df-fv 6057  df-ov 6816  df-oprab 6817  df-mpt2 6818  df-om 7231  df-1st 7333  df-2nd 7334  df-wrecs 7576  df-recs 7637  df-rdg 7675  df-oadd 7733  df-ni 9886  df-pli 9887 This theorem is referenced by: (None)
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