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Mirrors > Home > ILE Home > Th. List > nn0ob | GIF version |
Description: Alternate characterizations of an odd nonnegative integer. (Contributed by AV, 4-Jun-2020.) |
Ref | Expression |
---|---|
nn0ob | ⊢ (𝑁 ∈ ℕ0 → (((𝑁 + 1) / 2) ∈ ℕ0 ↔ ((𝑁 − 1) / 2) ∈ ℕ0)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | nn0o 11833 | . 2 ⊢ ((𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℕ0) → ((𝑁 − 1) / 2) ∈ ℕ0) | |
2 | nn0cn 9116 | . . . . . 6 ⊢ (𝑁 ∈ ℕ0 → 𝑁 ∈ ℂ) | |
3 | xp1d2m1eqxm1d2 9101 | . . . . . . 7 ⊢ (𝑁 ∈ ℂ → (((𝑁 + 1) / 2) − 1) = ((𝑁 − 1) / 2)) | |
4 | 3 | eqcomd 2170 | . . . . . 6 ⊢ (𝑁 ∈ ℂ → ((𝑁 − 1) / 2) = (((𝑁 + 1) / 2) − 1)) |
5 | 2, 4 | syl 14 | . . . . 5 ⊢ (𝑁 ∈ ℕ0 → ((𝑁 − 1) / 2) = (((𝑁 + 1) / 2) − 1)) |
6 | peano2cnm 8156 | . . . . . . . 8 ⊢ (𝑁 ∈ ℂ → (𝑁 − 1) ∈ ℂ) | |
7 | 2, 6 | syl 14 | . . . . . . 7 ⊢ (𝑁 ∈ ℕ0 → (𝑁 − 1) ∈ ℂ) |
8 | 7 | halfcld 9093 | . . . . . 6 ⊢ (𝑁 ∈ ℕ0 → ((𝑁 − 1) / 2) ∈ ℂ) |
9 | 1cnd 7907 | . . . . . 6 ⊢ (𝑁 ∈ ℕ0 → 1 ∈ ℂ) | |
10 | peano2nn0 9146 | . . . . . . . 8 ⊢ (𝑁 ∈ ℕ0 → (𝑁 + 1) ∈ ℕ0) | |
11 | 10 | nn0cnd 9161 | . . . . . . 7 ⊢ (𝑁 ∈ ℕ0 → (𝑁 + 1) ∈ ℂ) |
12 | 11 | halfcld 9093 | . . . . . 6 ⊢ (𝑁 ∈ ℕ0 → ((𝑁 + 1) / 2) ∈ ℂ) |
13 | 8, 9, 12 | addlsub 8260 | . . . . 5 ⊢ (𝑁 ∈ ℕ0 → ((((𝑁 − 1) / 2) + 1) = ((𝑁 + 1) / 2) ↔ ((𝑁 − 1) / 2) = (((𝑁 + 1) / 2) − 1))) |
14 | 5, 13 | mpbird 166 | . . . 4 ⊢ (𝑁 ∈ ℕ0 → (((𝑁 − 1) / 2) + 1) = ((𝑁 + 1) / 2)) |
15 | 14 | adantr 274 | . . 3 ⊢ ((𝑁 ∈ ℕ0 ∧ ((𝑁 − 1) / 2) ∈ ℕ0) → (((𝑁 − 1) / 2) + 1) = ((𝑁 + 1) / 2)) |
16 | peano2nn0 9146 | . . . 4 ⊢ (((𝑁 − 1) / 2) ∈ ℕ0 → (((𝑁 − 1) / 2) + 1) ∈ ℕ0) | |
17 | 16 | adantl 275 | . . 3 ⊢ ((𝑁 ∈ ℕ0 ∧ ((𝑁 − 1) / 2) ∈ ℕ0) → (((𝑁 − 1) / 2) + 1) ∈ ℕ0) |
18 | 15, 17 | eqeltrrd 2242 | . 2 ⊢ ((𝑁 ∈ ℕ0 ∧ ((𝑁 − 1) / 2) ∈ ℕ0) → ((𝑁 + 1) / 2) ∈ ℕ0) |
19 | 1, 18 | impbida 586 | 1 ⊢ (𝑁 ∈ ℕ0 → (((𝑁 + 1) / 2) ∈ ℕ0 ↔ ((𝑁 − 1) / 2) ∈ ℕ0)) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ∧ wa 103 ↔ wb 104 = wceq 1342 ∈ wcel 2135 (class class class)co 5837 ℂcc 7743 1c1 7746 + caddc 7748 − cmin 8061 / cdiv 8560 2c2 8900 ℕ0cn0 9106 |
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 1434 ax-7 1435 ax-gen 1436 ax-ie1 1480 ax-ie2 1481 ax-8 1491 ax-10 1492 ax-11 1493 ax-i12 1494 ax-bndl 1496 ax-4 1497 ax-17 1513 ax-i9 1517 ax-ial 1521 ax-i5r 1522 ax-13 2137 ax-14 2138 ax-ext 2146 ax-sep 4095 ax-pow 4148 ax-pr 4182 ax-un 4406 ax-setind 4509 ax-cnex 7836 ax-resscn 7837 ax-1cn 7838 ax-1re 7839 ax-icn 7840 ax-addcl 7841 ax-addrcl 7842 ax-mulcl 7843 ax-mulrcl 7844 ax-addcom 7845 ax-mulcom 7846 ax-addass 7847 ax-mulass 7848 ax-distr 7849 ax-i2m1 7850 ax-0lt1 7851 ax-1rid 7852 ax-0id 7853 ax-rnegex 7854 ax-precex 7855 ax-cnre 7856 ax-pre-ltirr 7857 ax-pre-ltwlin 7858 ax-pre-lttrn 7859 ax-pre-apti 7860 ax-pre-ltadd 7861 ax-pre-mulgt0 7862 ax-pre-mulext 7863 |
This theorem depends on definitions: df-bi 116 df-3or 968 df-3an 969 df-tru 1345 df-fal 1348 df-nf 1448 df-sb 1750 df-eu 2016 df-mo 2017 df-clab 2151 df-cleq 2157 df-clel 2160 df-nfc 2295 df-ne 2335 df-nel 2430 df-ral 2447 df-rex 2448 df-reu 2449 df-rmo 2450 df-rab 2451 df-v 2724 df-sbc 2948 df-dif 3114 df-un 3116 df-in 3118 df-ss 3125 df-pw 3556 df-sn 3577 df-pr 3578 df-op 3580 df-uni 3785 df-int 3820 df-br 3978 df-opab 4039 df-mpt 4040 df-id 4266 df-po 4269 df-iso 4270 df-xp 4605 df-rel 4606 df-cnv 4607 df-co 4608 df-dm 4609 df-rn 4610 df-res 4611 df-ima 4612 df-iota 5148 df-fun 5185 df-fn 5186 df-f 5187 df-fv 5191 df-riota 5793 df-ov 5840 df-oprab 5841 df-mpo 5842 df-pnf 7927 df-mnf 7928 df-xr 7929 df-ltxr 7930 df-le 7931 df-sub 8063 df-neg 8064 df-reap 8465 df-ap 8472 df-div 8561 df-inn 8850 df-2 8908 df-3 8909 df-4 8910 df-n0 9107 df-z 9184 df-uz 9459 |
This theorem is referenced by: nn0oddm1d2 11835 |
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