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Mirrors > Home > MPE Home > Th. List > nn0o | Structured version Visualization version GIF version |
Description: An alternate characterization of an odd nonnegative integer. (Contributed by AV, 28-May-2020.) (Proof shortened by AV, 2-Jun-2020.) |
Ref | Expression |
---|---|
nn0o | ⊢ ((𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℕ0) → ((𝑁 − 1) / 2) ∈ ℕ0) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | nn0o1gt2 15732 | . 2 ⊢ ((𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℕ0) → (𝑁 = 1 ∨ 2 < 𝑁)) | |
2 | 1m1e0 11710 | . . . . . . . 8 ⊢ (1 − 1) = 0 | |
3 | 2 | oveq1i 7166 | . . . . . . 7 ⊢ ((1 − 1) / 2) = (0 / 2) |
4 | 2cn 11713 | . . . . . . . 8 ⊢ 2 ∈ ℂ | |
5 | 2ne0 11742 | . . . . . . . 8 ⊢ 2 ≠ 0 | |
6 | 4, 5 | div0i 11374 | . . . . . . 7 ⊢ (0 / 2) = 0 |
7 | 3, 6 | eqtri 2844 | . . . . . 6 ⊢ ((1 − 1) / 2) = 0 |
8 | 0nn0 11913 | . . . . . 6 ⊢ 0 ∈ ℕ0 | |
9 | 7, 8 | eqeltri 2909 | . . . . 5 ⊢ ((1 − 1) / 2) ∈ ℕ0 |
10 | oveq1 7163 | . . . . . . . 8 ⊢ (𝑁 = 1 → (𝑁 − 1) = (1 − 1)) | |
11 | 10 | oveq1d 7171 | . . . . . . 7 ⊢ (𝑁 = 1 → ((𝑁 − 1) / 2) = ((1 − 1) / 2)) |
12 | 11 | eleq1d 2897 | . . . . . 6 ⊢ (𝑁 = 1 → (((𝑁 − 1) / 2) ∈ ℕ0 ↔ ((1 − 1) / 2) ∈ ℕ0)) |
13 | 12 | adantr 483 | . . . . 5 ⊢ ((𝑁 = 1 ∧ (𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℕ0)) → (((𝑁 − 1) / 2) ∈ ℕ0 ↔ ((1 − 1) / 2) ∈ ℕ0)) |
14 | 9, 13 | mpbiri 260 | . . . 4 ⊢ ((𝑁 = 1 ∧ (𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℕ0)) → ((𝑁 − 1) / 2) ∈ ℕ0) |
15 | 14 | ex 415 | . . 3 ⊢ (𝑁 = 1 → ((𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℕ0) → ((𝑁 − 1) / 2) ∈ ℕ0)) |
16 | 2z 12015 | . . . . . . . 8 ⊢ 2 ∈ ℤ | |
17 | 16 | a1i 11 | . . . . . . 7 ⊢ ((2 < 𝑁 ∧ (𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℕ0)) → 2 ∈ ℤ) |
18 | nn0z 12006 | . . . . . . . 8 ⊢ (𝑁 ∈ ℕ0 → 𝑁 ∈ ℤ) | |
19 | 18 | ad2antrl 726 | . . . . . . 7 ⊢ ((2 < 𝑁 ∧ (𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℕ0)) → 𝑁 ∈ ℤ) |
20 | 2re 11712 | . . . . . . . . . 10 ⊢ 2 ∈ ℝ | |
21 | nn0re 11907 | . . . . . . . . . 10 ⊢ (𝑁 ∈ ℕ0 → 𝑁 ∈ ℝ) | |
22 | ltle 10729 | . . . . . . . . . 10 ⊢ ((2 ∈ ℝ ∧ 𝑁 ∈ ℝ) → (2 < 𝑁 → 2 ≤ 𝑁)) | |
23 | 20, 21, 22 | sylancr 589 | . . . . . . . . 9 ⊢ (𝑁 ∈ ℕ0 → (2 < 𝑁 → 2 ≤ 𝑁)) |
24 | 23 | adantr 483 | . . . . . . . 8 ⊢ ((𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℕ0) → (2 < 𝑁 → 2 ≤ 𝑁)) |
25 | 24 | impcom 410 | . . . . . . 7 ⊢ ((2 < 𝑁 ∧ (𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℕ0)) → 2 ≤ 𝑁) |
26 | eluz2 12250 | . . . . . . 7 ⊢ (𝑁 ∈ (ℤ≥‘2) ↔ (2 ∈ ℤ ∧ 𝑁 ∈ ℤ ∧ 2 ≤ 𝑁)) | |
27 | 17, 19, 25, 26 | syl3anbrc 1339 | . . . . . 6 ⊢ ((2 < 𝑁 ∧ (𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℕ0)) → 𝑁 ∈ (ℤ≥‘2)) |
28 | simprr 771 | . . . . . 6 ⊢ ((2 < 𝑁 ∧ (𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℕ0)) → ((𝑁 + 1) / 2) ∈ ℕ0) | |
29 | 27, 28 | jca 514 | . . . . 5 ⊢ ((2 < 𝑁 ∧ (𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℕ0)) → (𝑁 ∈ (ℤ≥‘2) ∧ ((𝑁 + 1) / 2) ∈ ℕ0)) |
30 | nno 15733 | . . . . 5 ⊢ ((𝑁 ∈ (ℤ≥‘2) ∧ ((𝑁 + 1) / 2) ∈ ℕ0) → ((𝑁 − 1) / 2) ∈ ℕ) | |
31 | nnnn0 11905 | . . . . 5 ⊢ (((𝑁 − 1) / 2) ∈ ℕ → ((𝑁 − 1) / 2) ∈ ℕ0) | |
32 | 29, 30, 31 | 3syl 18 | . . . 4 ⊢ ((2 < 𝑁 ∧ (𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℕ0)) → ((𝑁 − 1) / 2) ∈ ℕ0) |
33 | 32 | ex 415 | . . 3 ⊢ (2 < 𝑁 → ((𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℕ0) → ((𝑁 − 1) / 2) ∈ ℕ0)) |
34 | 15, 33 | jaoi 853 | . 2 ⊢ ((𝑁 = 1 ∨ 2 < 𝑁) → ((𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℕ0) → ((𝑁 − 1) / 2) ∈ ℕ0)) |
35 | 1, 34 | mpcom 38 | 1 ⊢ ((𝑁 ∈ ℕ0 ∧ ((𝑁 + 1) / 2) ∈ ℕ0) → ((𝑁 − 1) / 2) ∈ ℕ0) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 208 ∧ wa 398 ∨ wo 843 = wceq 1537 ∈ wcel 2114 class class class wbr 5066 ‘cfv 6355 (class class class)co 7156 ℝcr 10536 0cc0 10537 1c1 10538 + caddc 10540 < clt 10675 ≤ cle 10676 − cmin 10870 / cdiv 11297 ℕcn 11638 2c2 11693 ℕ0cn0 11898 ℤcz 11982 ℤ≥cuz 12244 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1796 ax-4 1810 ax-5 1911 ax-6 1970 ax-7 2015 ax-8 2116 ax-9 2124 ax-10 2145 ax-11 2161 ax-12 2177 ax-ext 2793 ax-sep 5203 ax-nul 5210 ax-pow 5266 ax-pr 5330 ax-un 7461 ax-cnex 10593 ax-resscn 10594 ax-1cn 10595 ax-icn 10596 ax-addcl 10597 ax-addrcl 10598 ax-mulcl 10599 ax-mulrcl 10600 ax-mulcom 10601 ax-addass 10602 ax-mulass 10603 ax-distr 10604 ax-i2m1 10605 ax-1ne0 10606 ax-1rid 10607 ax-rnegex 10608 ax-rrecex 10609 ax-cnre 10610 ax-pre-lttri 10611 ax-pre-lttrn 10612 ax-pre-ltadd 10613 ax-pre-mulgt0 10614 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3or 1084 df-3an 1085 df-tru 1540 df-ex 1781 df-nf 1785 df-sb 2070 df-mo 2622 df-eu 2654 df-clab 2800 df-cleq 2814 df-clel 2893 df-nfc 2963 df-ne 3017 df-nel 3124 df-ral 3143 df-rex 3144 df-reu 3145 df-rmo 3146 df-rab 3147 df-v 3496 df-sbc 3773 df-csb 3884 df-dif 3939 df-un 3941 df-in 3943 df-ss 3952 df-pss 3954 df-nul 4292 df-if 4468 df-pw 4541 df-sn 4568 df-pr 4570 df-tp 4572 df-op 4574 df-uni 4839 df-iun 4921 df-br 5067 df-opab 5129 df-mpt 5147 df-tr 5173 df-id 5460 df-eprel 5465 df-po 5474 df-so 5475 df-fr 5514 df-we 5516 df-xp 5561 df-rel 5562 df-cnv 5563 df-co 5564 df-dm 5565 df-rn 5566 df-res 5567 df-ima 5568 df-pred 6148 df-ord 6194 df-on 6195 df-lim 6196 df-suc 6197 df-iota 6314 df-fun 6357 df-fn 6358 df-f 6359 df-f1 6360 df-fo 6361 df-f1o 6362 df-fv 6363 df-riota 7114 df-ov 7159 df-oprab 7160 df-mpo 7161 df-om 7581 df-wrecs 7947 df-recs 8008 df-rdg 8046 df-er 8289 df-en 8510 df-dom 8511 df-sdom 8512 df-pnf 10677 df-mnf 10678 df-xr 10679 df-ltxr 10680 df-le 10681 df-sub 10872 df-neg 10873 df-div 11298 df-nn 11639 df-2 11701 df-3 11702 df-4 11703 df-n0 11899 df-z 11983 df-uz 12245 df-rp 12391 |
This theorem is referenced by: nn0ob 15735 nn0onn0ex 44603 nneom 44607 flnn0div2ge 44613 flnn0ohalf 44614 |
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