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Mirrors > Home > ILE Home > Th. List > nn0oddm1d2 | GIF version |
Description: A positive integer is odd iff its predecessor divided by 2 is a positive integer. (Contributed by AV, 28-Jun-2021.) |
Ref | Expression |
---|---|
nn0oddm1d2 | ⊢ (𝑁 ∈ ℕ0 → (¬ 2 ∥ 𝑁 ↔ ((𝑁 − 1) / 2) ∈ ℕ0)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | nn0z 9259 | . . 3 ⊢ (𝑁 ∈ ℕ0 → 𝑁 ∈ ℤ) | |
2 | oddp1d2 11875 | . . 3 ⊢ (𝑁 ∈ ℤ → (¬ 2 ∥ 𝑁 ↔ ((𝑁 + 1) / 2) ∈ ℤ)) | |
3 | 1, 2 | syl 14 | . 2 ⊢ (𝑁 ∈ ℕ0 → (¬ 2 ∥ 𝑁 ↔ ((𝑁 + 1) / 2) ∈ ℤ)) |
4 | nn0re 9171 | . . . . . . . . 9 ⊢ (𝑁 ∈ ℕ0 → 𝑁 ∈ ℝ) | |
5 | 1red 7960 | . . . . . . . . 9 ⊢ (𝑁 ∈ ℕ0 → 1 ∈ ℝ) | |
6 | nn0ge0 9187 | . . . . . . . . 9 ⊢ (𝑁 ∈ ℕ0 → 0 ≤ 𝑁) | |
7 | 0le1 8425 | . . . . . . . . . 10 ⊢ 0 ≤ 1 | |
8 | 7 | a1i 9 | . . . . . . . . 9 ⊢ (𝑁 ∈ ℕ0 → 0 ≤ 1) |
9 | 4, 5, 6, 8 | addge0d 8466 | . . . . . . . 8 ⊢ (𝑁 ∈ ℕ0 → 0 ≤ (𝑁 + 1)) |
10 | peano2nn0 9202 | . . . . . . . . . 10 ⊢ (𝑁 ∈ ℕ0 → (𝑁 + 1) ∈ ℕ0) | |
11 | 10 | nn0red 9216 | . . . . . . . . 9 ⊢ (𝑁 ∈ ℕ0 → (𝑁 + 1) ∈ ℝ) |
12 | 2re 8975 | . . . . . . . . . 10 ⊢ 2 ∈ ℝ | |
13 | 12 | a1i 9 | . . . . . . . . 9 ⊢ (𝑁 ∈ ℕ0 → 2 ∈ ℝ) |
14 | 2pos 8996 | . . . . . . . . . 10 ⊢ 0 < 2 | |
15 | 14 | a1i 9 | . . . . . . . . 9 ⊢ (𝑁 ∈ ℕ0 → 0 < 2) |
16 | ge0div 8814 | . . . . . . . . 9 ⊢ (((𝑁 + 1) ∈ ℝ ∧ 2 ∈ ℝ ∧ 0 < 2) → (0 ≤ (𝑁 + 1) ↔ 0 ≤ ((𝑁 + 1) / 2))) | |
17 | 11, 13, 15, 16 | syl3anc 1238 | . . . . . . . 8 ⊢ (𝑁 ∈ ℕ0 → (0 ≤ (𝑁 + 1) ↔ 0 ≤ ((𝑁 + 1) / 2))) |
18 | 9, 17 | mpbid 147 | . . . . . . 7 ⊢ (𝑁 ∈ ℕ0 → 0 ≤ ((𝑁 + 1) / 2)) |
19 | 18 | anim1i 340 | . . . . . 6 ⊢ ((𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℤ) → (0 ≤ ((𝑁 + 1) / 2) ∧ ((𝑁 + 1) / 2) ∈ ℤ)) |
20 | 19 | ancomd 267 | . . . . 5 ⊢ ((𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℤ) → (((𝑁 + 1) / 2) ∈ ℤ ∧ 0 ≤ ((𝑁 + 1) / 2))) |
21 | elnn0z 9252 | . . . . 5 ⊢ (((𝑁 + 1) / 2) ∈ ℕ0 ↔ (((𝑁 + 1) / 2) ∈ ℤ ∧ 0 ≤ ((𝑁 + 1) / 2))) | |
22 | 20, 21 | sylibr 134 | . . . 4 ⊢ ((𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℤ) → ((𝑁 + 1) / 2) ∈ ℕ0) |
23 | 22 | ex 115 | . . 3 ⊢ (𝑁 ∈ ℕ0 → (((𝑁 + 1) / 2) ∈ ℤ → ((𝑁 + 1) / 2) ∈ ℕ0)) |
24 | nn0z 9259 | . . 3 ⊢ (((𝑁 + 1) / 2) ∈ ℕ0 → ((𝑁 + 1) / 2) ∈ ℤ) | |
25 | 23, 24 | impbid1 142 | . 2 ⊢ (𝑁 ∈ ℕ0 → (((𝑁 + 1) / 2) ∈ ℤ ↔ ((𝑁 + 1) / 2) ∈ ℕ0)) |
26 | nn0ob 11893 | . 2 ⊢ (𝑁 ∈ ℕ0 → (((𝑁 + 1) / 2) ∈ ℕ0 ↔ ((𝑁 − 1) / 2) ∈ ℕ0)) | |
27 | 3, 25, 26 | 3bitrd 214 | 1 ⊢ (𝑁 ∈ ℕ0 → (¬ 2 ∥ 𝑁 ↔ ((𝑁 − 1) / 2) ∈ ℕ0)) |
Colors of variables: wff set class |
Syntax hints: ¬ wn 3 → wi 4 ∧ wa 104 ↔ wb 105 ∈ wcel 2148 class class class wbr 4000 (class class class)co 5869 ℝcr 7798 0cc0 7799 1c1 7800 + caddc 7802 < clt 7979 ≤ cle 7980 − cmin 8115 / cdiv 8615 2c2 8956 ℕ0cn0 9162 ℤcz 9239 ∥ cdvds 11775 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 106 ax-ia2 107 ax-ia3 108 ax-in1 614 ax-in2 615 ax-io 709 ax-5 1447 ax-7 1448 ax-gen 1449 ax-ie1 1493 ax-ie2 1494 ax-8 1504 ax-10 1505 ax-11 1506 ax-i12 1507 ax-bndl 1509 ax-4 1510 ax-17 1526 ax-i9 1530 ax-ial 1534 ax-i5r 1535 ax-13 2150 ax-14 2151 ax-ext 2159 ax-sep 4118 ax-pow 4171 ax-pr 4206 ax-un 4430 ax-setind 4533 ax-cnex 7890 ax-resscn 7891 ax-1cn 7892 ax-1re 7893 ax-icn 7894 ax-addcl 7895 ax-addrcl 7896 ax-mulcl 7897 ax-mulrcl 7898 ax-addcom 7899 ax-mulcom 7900 ax-addass 7901 ax-mulass 7902 ax-distr 7903 ax-i2m1 7904 ax-0lt1 7905 ax-1rid 7906 ax-0id 7907 ax-rnegex 7908 ax-precex 7909 ax-cnre 7910 ax-pre-ltirr 7911 ax-pre-ltwlin 7912 ax-pre-lttrn 7913 ax-pre-apti 7914 ax-pre-ltadd 7915 ax-pre-mulgt0 7916 ax-pre-mulext 7917 |
This theorem depends on definitions: df-bi 117 df-3or 979 df-3an 980 df-tru 1356 df-fal 1359 df-xor 1376 df-nf 1461 df-sb 1763 df-eu 2029 df-mo 2030 df-clab 2164 df-cleq 2170 df-clel 2173 df-nfc 2308 df-ne 2348 df-nel 2443 df-ral 2460 df-rex 2461 df-reu 2462 df-rmo 2463 df-rab 2464 df-v 2739 df-sbc 2963 df-dif 3131 df-un 3133 df-in 3135 df-ss 3142 df-pw 3576 df-sn 3597 df-pr 3598 df-op 3600 df-uni 3808 df-int 3843 df-br 4001 df-opab 4062 df-mpt 4063 df-id 4290 df-po 4293 df-iso 4294 df-xp 4629 df-rel 4630 df-cnv 4631 df-co 4632 df-dm 4633 df-rn 4634 df-res 4635 df-ima 4636 df-iota 5174 df-fun 5214 df-fn 5215 df-f 5216 df-fv 5220 df-riota 5825 df-ov 5872 df-oprab 5873 df-mpo 5874 df-pnf 7981 df-mnf 7982 df-xr 7983 df-ltxr 7984 df-le 7985 df-sub 8117 df-neg 8118 df-reap 8519 df-ap 8526 df-div 8616 df-inn 8906 df-2 8964 df-3 8965 df-4 8966 df-n0 9163 df-z 9240 df-uz 9515 df-dvds 11776 |
This theorem is referenced by: lgsval 14069 lgsfvalg 14070 |
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