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Mirrors > Home > ILE Home > Th. List > nneo | GIF version |
Description: A positive integer is even or odd but not both. (Contributed by NM, 1-Jan-2006.) (Proof shortened by Mario Carneiro, 18-May-2014.) |
Ref | Expression |
---|---|
nneo | ⊢ (𝑁 ∈ ℕ → ((𝑁 / 2) ∈ ℕ ↔ ¬ ((𝑁 + 1) / 2) ∈ ℕ)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | nncn 8841 | . . . . . 6 ⊢ (𝑁 ∈ ℕ → 𝑁 ∈ ℂ) | |
2 | peano2cn 8010 | . . . . . 6 ⊢ (𝑁 ∈ ℂ → (𝑁 + 1) ∈ ℂ) | |
3 | 1, 2 | syl 14 | . . . . 5 ⊢ (𝑁 ∈ ℕ → (𝑁 + 1) ∈ ℂ) |
4 | 2cnd 8906 | . . . . 5 ⊢ (𝑁 ∈ ℕ → 2 ∈ ℂ) | |
5 | 2ap0 8926 | . . . . . 6 ⊢ 2 # 0 | |
6 | 5 | a1i 9 | . . . . 5 ⊢ (𝑁 ∈ ℕ → 2 # 0) |
7 | 3, 4, 6 | divcanap2d 8665 | . . . 4 ⊢ (𝑁 ∈ ℕ → (2 · ((𝑁 + 1) / 2)) = (𝑁 + 1)) |
8 | 1, 4, 6 | divcanap2d 8665 | . . . . 5 ⊢ (𝑁 ∈ ℕ → (2 · (𝑁 / 2)) = 𝑁) |
9 | 8 | oveq1d 5839 | . . . 4 ⊢ (𝑁 ∈ ℕ → ((2 · (𝑁 / 2)) + 1) = (𝑁 + 1)) |
10 | 7, 9 | eqtr4d 2193 | . . 3 ⊢ (𝑁 ∈ ℕ → (2 · ((𝑁 + 1) / 2)) = ((2 · (𝑁 / 2)) + 1)) |
11 | nnz 9186 | . . . . . 6 ⊢ (((𝑁 + 1) / 2) ∈ ℕ → ((𝑁 + 1) / 2) ∈ ℤ) | |
12 | nnz 9186 | . . . . . 6 ⊢ ((𝑁 / 2) ∈ ℕ → (𝑁 / 2) ∈ ℤ) | |
13 | zneo 9265 | . . . . . 6 ⊢ ((((𝑁 + 1) / 2) ∈ ℤ ∧ (𝑁 / 2) ∈ ℤ) → (2 · ((𝑁 + 1) / 2)) ≠ ((2 · (𝑁 / 2)) + 1)) | |
14 | 11, 12, 13 | syl2an 287 | . . . . 5 ⊢ ((((𝑁 + 1) / 2) ∈ ℕ ∧ (𝑁 / 2) ∈ ℕ) → (2 · ((𝑁 + 1) / 2)) ≠ ((2 · (𝑁 / 2)) + 1)) |
15 | 14 | expcom 115 | . . . 4 ⊢ ((𝑁 / 2) ∈ ℕ → (((𝑁 + 1) / 2) ∈ ℕ → (2 · ((𝑁 + 1) / 2)) ≠ ((2 · (𝑁 / 2)) + 1))) |
16 | 15 | necon2bd 2385 | . . 3 ⊢ ((𝑁 / 2) ∈ ℕ → ((2 · ((𝑁 + 1) / 2)) = ((2 · (𝑁 / 2)) + 1) → ¬ ((𝑁 + 1) / 2) ∈ ℕ)) |
17 | 10, 16 | syl5com 29 | . 2 ⊢ (𝑁 ∈ ℕ → ((𝑁 / 2) ∈ ℕ → ¬ ((𝑁 + 1) / 2) ∈ ℕ)) |
18 | nneoor 9266 | . . . 4 ⊢ (𝑁 ∈ ℕ → ((𝑁 / 2) ∈ ℕ ∨ ((𝑁 + 1) / 2) ∈ ℕ)) | |
19 | 18 | orcomd 719 | . . 3 ⊢ (𝑁 ∈ ℕ → (((𝑁 + 1) / 2) ∈ ℕ ∨ (𝑁 / 2) ∈ ℕ)) |
20 | 19 | ord 714 | . 2 ⊢ (𝑁 ∈ ℕ → (¬ ((𝑁 + 1) / 2) ∈ ℕ → (𝑁 / 2) ∈ ℕ)) |
21 | 17, 20 | impbid 128 | 1 ⊢ (𝑁 ∈ ℕ → ((𝑁 / 2) ∈ ℕ ↔ ¬ ((𝑁 + 1) / 2) ∈ ℕ)) |
Colors of variables: wff set class |
Syntax hints: ¬ wn 3 → wi 4 ↔ wb 104 = wceq 1335 ∈ wcel 2128 ≠ wne 2327 class class class wbr 3965 (class class class)co 5824 ℂcc 7730 0cc0 7732 1c1 7733 + caddc 7735 · cmul 7737 # cap 8456 / cdiv 8545 ℕcn 8833 2c2 8884 ℤcz 9167 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-in1 604 ax-in2 605 ax-io 699 ax-5 1427 ax-7 1428 ax-gen 1429 ax-ie1 1473 ax-ie2 1474 ax-8 1484 ax-10 1485 ax-11 1486 ax-i12 1487 ax-bndl 1489 ax-4 1490 ax-17 1506 ax-i9 1510 ax-ial 1514 ax-i5r 1515 ax-13 2130 ax-14 2131 ax-ext 2139 ax-sep 4082 ax-pow 4135 ax-pr 4169 ax-un 4393 ax-setind 4496 ax-cnex 7823 ax-resscn 7824 ax-1cn 7825 ax-1re 7826 ax-icn 7827 ax-addcl 7828 ax-addrcl 7829 ax-mulcl 7830 ax-mulrcl 7831 ax-addcom 7832 ax-mulcom 7833 ax-addass 7834 ax-mulass 7835 ax-distr 7836 ax-i2m1 7837 ax-0lt1 7838 ax-1rid 7839 ax-0id 7840 ax-rnegex 7841 ax-precex 7842 ax-cnre 7843 ax-pre-ltirr 7844 ax-pre-ltwlin 7845 ax-pre-lttrn 7846 ax-pre-apti 7847 ax-pre-ltadd 7848 ax-pre-mulgt0 7849 ax-pre-mulext 7850 |
This theorem depends on definitions: df-bi 116 df-3or 964 df-3an 965 df-tru 1338 df-fal 1341 df-nf 1441 df-sb 1743 df-eu 2009 df-mo 2010 df-clab 2144 df-cleq 2150 df-clel 2153 df-nfc 2288 df-ne 2328 df-nel 2423 df-ral 2440 df-rex 2441 df-reu 2442 df-rmo 2443 df-rab 2444 df-v 2714 df-sbc 2938 df-dif 3104 df-un 3106 df-in 3108 df-ss 3115 df-pw 3545 df-sn 3566 df-pr 3567 df-op 3569 df-uni 3773 df-int 3808 df-br 3966 df-opab 4026 df-id 4253 df-po 4256 df-iso 4257 df-xp 4592 df-rel 4593 df-cnv 4594 df-co 4595 df-dm 4596 df-iota 5135 df-fun 5172 df-fv 5178 df-riota 5780 df-ov 5827 df-oprab 5828 df-mpo 5829 df-pnf 7914 df-mnf 7915 df-xr 7916 df-ltxr 7917 df-le 7918 df-sub 8048 df-neg 8049 df-reap 8450 df-ap 8457 df-div 8546 df-inn 8834 df-2 8892 df-n0 9091 df-z 9168 |
This theorem is referenced by: nneoi 9268 |
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