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Mirrors > Home > ILE Home > Th. List > evennn02n | GIF version |
Description: A nonnegative integer is even iff it is twice another nonnegative integer. (Contributed by AV, 12-Aug-2021.) |
Ref | Expression |
---|---|
evennn02n | ⊢ (𝑁 ∈ ℕ0 → (2 ∥ 𝑁 ↔ ∃𝑛 ∈ ℕ0 (2 · 𝑛) = 𝑁)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eleq1 2177 | . . . . . . . 8 ⊢ ((2 · 𝑛) = 𝑁 → ((2 · 𝑛) ∈ ℕ0 ↔ 𝑁 ∈ ℕ0)) | |
2 | simpr 109 | . . . . . . . . . 10 ⊢ (((2 · 𝑛) ∈ ℕ0 ∧ 𝑛 ∈ ℤ) → 𝑛 ∈ ℤ) | |
3 | 2re 8700 | . . . . . . . . . . . 12 ⊢ 2 ∈ ℝ | |
4 | 3 | a1i 9 | . . . . . . . . . . 11 ⊢ (((2 · 𝑛) ∈ ℕ0 ∧ 𝑛 ∈ ℤ) → 2 ∈ ℝ) |
5 | zre 8962 | . . . . . . . . . . . 12 ⊢ (𝑛 ∈ ℤ → 𝑛 ∈ ℝ) | |
6 | 5 | adantl 273 | . . . . . . . . . . 11 ⊢ (((2 · 𝑛) ∈ ℕ0 ∧ 𝑛 ∈ ℤ) → 𝑛 ∈ ℝ) |
7 | 2pos 8721 | . . . . . . . . . . . 12 ⊢ 0 < 2 | |
8 | 7 | a1i 9 | . . . . . . . . . . 11 ⊢ (((2 · 𝑛) ∈ ℕ0 ∧ 𝑛 ∈ ℤ) → 0 < 2) |
9 | nn0ge0 8906 | . . . . . . . . . . . 12 ⊢ ((2 · 𝑛) ∈ ℕ0 → 0 ≤ (2 · 𝑛)) | |
10 | 9 | adantr 272 | . . . . . . . . . . 11 ⊢ (((2 · 𝑛) ∈ ℕ0 ∧ 𝑛 ∈ ℤ) → 0 ≤ (2 · 𝑛)) |
11 | prodge0 8522 | . . . . . . . . . . 11 ⊢ (((2 ∈ ℝ ∧ 𝑛 ∈ ℝ) ∧ (0 < 2 ∧ 0 ≤ (2 · 𝑛))) → 0 ≤ 𝑛) | |
12 | 4, 6, 8, 10, 11 | syl22anc 1200 | . . . . . . . . . 10 ⊢ (((2 · 𝑛) ∈ ℕ0 ∧ 𝑛 ∈ ℤ) → 0 ≤ 𝑛) |
13 | elnn0z 8971 | . . . . . . . . . 10 ⊢ (𝑛 ∈ ℕ0 ↔ (𝑛 ∈ ℤ ∧ 0 ≤ 𝑛)) | |
14 | 2, 12, 13 | sylanbrc 411 | . . . . . . . . 9 ⊢ (((2 · 𝑛) ∈ ℕ0 ∧ 𝑛 ∈ ℤ) → 𝑛 ∈ ℕ0) |
15 | 14 | ex 114 | . . . . . . . 8 ⊢ ((2 · 𝑛) ∈ ℕ0 → (𝑛 ∈ ℤ → 𝑛 ∈ ℕ0)) |
16 | 1, 15 | syl6bir 163 | . . . . . . 7 ⊢ ((2 · 𝑛) = 𝑁 → (𝑁 ∈ ℕ0 → (𝑛 ∈ ℤ → 𝑛 ∈ ℕ0))) |
17 | 16 | com13 80 | . . . . . 6 ⊢ (𝑛 ∈ ℤ → (𝑁 ∈ ℕ0 → ((2 · 𝑛) = 𝑁 → 𝑛 ∈ ℕ0))) |
18 | 17 | impcom 124 | . . . . 5 ⊢ ((𝑁 ∈ ℕ0 ∧ 𝑛 ∈ ℤ) → ((2 · 𝑛) = 𝑁 → 𝑛 ∈ ℕ0)) |
19 | 18 | pm4.71rd 389 | . . . 4 ⊢ ((𝑁 ∈ ℕ0 ∧ 𝑛 ∈ ℤ) → ((2 · 𝑛) = 𝑁 ↔ (𝑛 ∈ ℕ0 ∧ (2 · 𝑛) = 𝑁))) |
20 | 19 | bicomd 140 | . . 3 ⊢ ((𝑁 ∈ ℕ0 ∧ 𝑛 ∈ ℤ) → ((𝑛 ∈ ℕ0 ∧ (2 · 𝑛) = 𝑁) ↔ (2 · 𝑛) = 𝑁)) |
21 | 20 | rexbidva 2408 | . 2 ⊢ (𝑁 ∈ ℕ0 → (∃𝑛 ∈ ℤ (𝑛 ∈ ℕ0 ∧ (2 · 𝑛) = 𝑁) ↔ ∃𝑛 ∈ ℤ (2 · 𝑛) = 𝑁)) |
22 | nn0ssz 8976 | . . 3 ⊢ ℕ0 ⊆ ℤ | |
23 | rexss 3130 | . . 3 ⊢ (ℕ0 ⊆ ℤ → (∃𝑛 ∈ ℕ0 (2 · 𝑛) = 𝑁 ↔ ∃𝑛 ∈ ℤ (𝑛 ∈ ℕ0 ∧ (2 · 𝑛) = 𝑁))) | |
24 | 22, 23 | mp1i 10 | . 2 ⊢ (𝑁 ∈ ℕ0 → (∃𝑛 ∈ ℕ0 (2 · 𝑛) = 𝑁 ↔ ∃𝑛 ∈ ℤ (𝑛 ∈ ℕ0 ∧ (2 · 𝑛) = 𝑁))) |
25 | even2n 11419 | . . 3 ⊢ (2 ∥ 𝑁 ↔ ∃𝑛 ∈ ℤ (2 · 𝑛) = 𝑁) | |
26 | 25 | a1i 9 | . 2 ⊢ (𝑁 ∈ ℕ0 → (2 ∥ 𝑁 ↔ ∃𝑛 ∈ ℤ (2 · 𝑛) = 𝑁)) |
27 | 21, 24, 26 | 3bitr4rd 220 | 1 ⊢ (𝑁 ∈ ℕ0 → (2 ∥ 𝑁 ↔ ∃𝑛 ∈ ℕ0 (2 · 𝑛) = 𝑁)) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ∧ wa 103 ↔ wb 104 = wceq 1314 ∈ wcel 1463 ∃wrex 2391 ⊆ wss 3037 class class class wbr 3895 (class class class)co 5728 ℝcr 7546 0cc0 7547 · cmul 7552 < clt 7724 ≤ cle 7725 2c2 8681 ℕ0cn0 8881 ℤcz 8958 ∥ cdvds 11341 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-in1 586 ax-in2 587 ax-io 681 ax-5 1406 ax-7 1407 ax-gen 1408 ax-ie1 1452 ax-ie2 1453 ax-8 1465 ax-10 1466 ax-11 1467 ax-i12 1468 ax-bndl 1469 ax-4 1470 ax-13 1474 ax-14 1475 ax-17 1489 ax-i9 1493 ax-ial 1497 ax-i5r 1498 ax-ext 2097 ax-sep 4006 ax-pow 4058 ax-pr 4091 ax-un 4315 ax-setind 4412 ax-cnex 7636 ax-resscn 7637 ax-1cn 7638 ax-1re 7639 ax-icn 7640 ax-addcl 7641 ax-addrcl 7642 ax-mulcl 7643 ax-mulrcl 7644 ax-addcom 7645 ax-mulcom 7646 ax-addass 7647 ax-mulass 7648 ax-distr 7649 ax-i2m1 7650 ax-0lt1 7651 ax-1rid 7652 ax-0id 7653 ax-rnegex 7654 ax-cnre 7656 ax-pre-ltirr 7657 ax-pre-ltwlin 7658 ax-pre-lttrn 7659 ax-pre-ltadd 7661 ax-pre-mulgt0 7662 |
This theorem depends on definitions: df-bi 116 df-3or 946 df-3an 947 df-tru 1317 df-fal 1320 df-nf 1420 df-sb 1719 df-eu 1978 df-mo 1979 df-clab 2102 df-cleq 2108 df-clel 2111 df-nfc 2244 df-ne 2283 df-nel 2378 df-ral 2395 df-rex 2396 df-reu 2397 df-rab 2399 df-v 2659 df-sbc 2879 df-dif 3039 df-un 3041 df-in 3043 df-ss 3050 df-pw 3478 df-sn 3499 df-pr 3500 df-op 3502 df-uni 3703 df-int 3738 df-br 3896 df-opab 3950 df-id 4175 df-xp 4505 df-rel 4506 df-cnv 4507 df-co 4508 df-dm 4509 df-iota 5046 df-fun 5083 df-fv 5089 df-riota 5684 df-ov 5731 df-oprab 5732 df-mpo 5733 df-pnf 7726 df-mnf 7727 df-xr 7728 df-ltxr 7729 df-le 7730 df-sub 7858 df-neg 7859 df-inn 8631 df-2 8689 df-n0 8882 df-z 8959 df-dvds 11342 |
This theorem is referenced by: (None) |
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