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Mirrors > Home > ILE Home > Th. List > nn0lt2 | GIF version |
Description: A nonnegative integer less than 2 must be 0 or 1. (Contributed by Alexander van der Vekens, 16-Sep-2018.) |
Ref | Expression |
---|---|
nn0lt2 | ⊢ ((𝑁 ∈ ℕ0 ∧ 𝑁 < 2) → (𝑁 = 0 ∨ 𝑁 = 1)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | olc 700 | . . 3 ⊢ (𝑁 = 1 → (𝑁 = 0 ∨ 𝑁 = 1)) | |
2 | 1 | a1i 9 | . 2 ⊢ ((𝑁 ∈ ℕ0 ∧ 𝑁 < 2) → (𝑁 = 1 → (𝑁 = 0 ∨ 𝑁 = 1))) |
3 | nn0z 9074 | . . . . . 6 ⊢ (𝑁 ∈ ℕ0 → 𝑁 ∈ ℤ) | |
4 | 2z 9082 | . . . . . 6 ⊢ 2 ∈ ℤ | |
5 | zltlem1 9111 | . . . . . 6 ⊢ ((𝑁 ∈ ℤ ∧ 2 ∈ ℤ) → (𝑁 < 2 ↔ 𝑁 ≤ (2 − 1))) | |
6 | 3, 4, 5 | sylancl 409 | . . . . 5 ⊢ (𝑁 ∈ ℕ0 → (𝑁 < 2 ↔ 𝑁 ≤ (2 − 1))) |
7 | 2m1e1 8838 | . . . . . 6 ⊢ (2 − 1) = 1 | |
8 | 7 | breq2i 3937 | . . . . 5 ⊢ (𝑁 ≤ (2 − 1) ↔ 𝑁 ≤ 1) |
9 | 6, 8 | syl6bb 195 | . . . 4 ⊢ (𝑁 ∈ ℕ0 → (𝑁 < 2 ↔ 𝑁 ≤ 1)) |
10 | necom 2392 | . . . . 5 ⊢ (𝑁 ≠ 1 ↔ 1 ≠ 𝑁) | |
11 | 1z 9080 | . . . . . . . 8 ⊢ 1 ∈ ℤ | |
12 | zltlen 9129 | . . . . . . . 8 ⊢ ((𝑁 ∈ ℤ ∧ 1 ∈ ℤ) → (𝑁 < 1 ↔ (𝑁 ≤ 1 ∧ 1 ≠ 𝑁))) | |
13 | 3, 11, 12 | sylancl 409 | . . . . . . 7 ⊢ (𝑁 ∈ ℕ0 → (𝑁 < 1 ↔ (𝑁 ≤ 1 ∧ 1 ≠ 𝑁))) |
14 | nn0lt10b 9131 | . . . . . . . . . 10 ⊢ (𝑁 ∈ ℕ0 → (𝑁 < 1 ↔ 𝑁 = 0)) | |
15 | 14 | biimpa 294 | . . . . . . . . 9 ⊢ ((𝑁 ∈ ℕ0 ∧ 𝑁 < 1) → 𝑁 = 0) |
16 | 15 | orcd 722 | . . . . . . . 8 ⊢ ((𝑁 ∈ ℕ0 ∧ 𝑁 < 1) → (𝑁 = 0 ∨ 𝑁 = 1)) |
17 | 16 | ex 114 | . . . . . . 7 ⊢ (𝑁 ∈ ℕ0 → (𝑁 < 1 → (𝑁 = 0 ∨ 𝑁 = 1))) |
18 | 13, 17 | sylbird 169 | . . . . . 6 ⊢ (𝑁 ∈ ℕ0 → ((𝑁 ≤ 1 ∧ 1 ≠ 𝑁) → (𝑁 = 0 ∨ 𝑁 = 1))) |
19 | 18 | expd 256 | . . . . 5 ⊢ (𝑁 ∈ ℕ0 → (𝑁 ≤ 1 → (1 ≠ 𝑁 → (𝑁 = 0 ∨ 𝑁 = 1)))) |
20 | 10, 19 | syl7bi 164 | . . . 4 ⊢ (𝑁 ∈ ℕ0 → (𝑁 ≤ 1 → (𝑁 ≠ 1 → (𝑁 = 0 ∨ 𝑁 = 1)))) |
21 | 9, 20 | sylbid 149 | . . 3 ⊢ (𝑁 ∈ ℕ0 → (𝑁 < 2 → (𝑁 ≠ 1 → (𝑁 = 0 ∨ 𝑁 = 1)))) |
22 | 21 | imp 123 | . 2 ⊢ ((𝑁 ∈ ℕ0 ∧ 𝑁 < 2) → (𝑁 ≠ 1 → (𝑁 = 0 ∨ 𝑁 = 1))) |
23 | zdceq 9126 | . . . . 5 ⊢ ((𝑁 ∈ ℤ ∧ 1 ∈ ℤ) → DECID 𝑁 = 1) | |
24 | 3, 11, 23 | sylancl 409 | . . . 4 ⊢ (𝑁 ∈ ℕ0 → DECID 𝑁 = 1) |
25 | 24 | adantr 274 | . . 3 ⊢ ((𝑁 ∈ ℕ0 ∧ 𝑁 < 2) → DECID 𝑁 = 1) |
26 | dcne 2319 | . . 3 ⊢ (DECID 𝑁 = 1 ↔ (𝑁 = 1 ∨ 𝑁 ≠ 1)) | |
27 | 25, 26 | sylib 121 | . 2 ⊢ ((𝑁 ∈ ℕ0 ∧ 𝑁 < 2) → (𝑁 = 1 ∨ 𝑁 ≠ 1)) |
28 | 2, 22, 27 | mpjaod 707 | 1 ⊢ ((𝑁 ∈ ℕ0 ∧ 𝑁 < 2) → (𝑁 = 0 ∨ 𝑁 = 1)) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ∧ wa 103 ↔ wb 104 ∨ wo 697 DECID wdc 819 = wceq 1331 ∈ wcel 1480 ≠ wne 2308 class class class wbr 3929 (class class class)co 5774 0cc0 7620 1c1 7621 < clt 7800 ≤ cle 7801 − cmin 7933 2c2 8771 ℕ0cn0 8977 ℤcz 9054 |
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 603 ax-in2 604 ax-io 698 ax-5 1423 ax-7 1424 ax-gen 1425 ax-ie1 1469 ax-ie2 1470 ax-8 1482 ax-10 1483 ax-11 1484 ax-i12 1485 ax-bndl 1486 ax-4 1487 ax-13 1491 ax-14 1492 ax-17 1506 ax-i9 1510 ax-ial 1514 ax-i5r 1515 ax-ext 2121 ax-sep 4046 ax-pow 4098 ax-pr 4131 ax-un 4355 ax-setind 4452 ax-cnex 7711 ax-resscn 7712 ax-1cn 7713 ax-1re 7714 ax-icn 7715 ax-addcl 7716 ax-addrcl 7717 ax-mulcl 7718 ax-mulrcl 7719 ax-addcom 7720 ax-mulcom 7721 ax-addass 7722 ax-mulass 7723 ax-distr 7724 ax-i2m1 7725 ax-0lt1 7726 ax-1rid 7727 ax-0id 7728 ax-rnegex 7729 ax-precex 7730 ax-cnre 7731 ax-pre-ltirr 7732 ax-pre-ltwlin 7733 ax-pre-lttrn 7734 ax-pre-apti 7735 ax-pre-ltadd 7736 ax-pre-mulgt0 7737 |
This theorem depends on definitions: df-bi 116 df-dc 820 df-3or 963 df-3an 964 df-tru 1334 df-fal 1337 df-nf 1437 df-sb 1736 df-eu 2002 df-mo 2003 df-clab 2126 df-cleq 2132 df-clel 2135 df-nfc 2270 df-ne 2309 df-nel 2404 df-ral 2421 df-rex 2422 df-reu 2423 df-rab 2425 df-v 2688 df-sbc 2910 df-dif 3073 df-un 3075 df-in 3077 df-ss 3084 df-pw 3512 df-sn 3533 df-pr 3534 df-op 3536 df-uni 3737 df-int 3772 df-br 3930 df-opab 3990 df-id 4215 df-xp 4545 df-rel 4546 df-cnv 4547 df-co 4548 df-dm 4549 df-iota 5088 df-fun 5125 df-fv 5131 df-riota 5730 df-ov 5777 df-oprab 5778 df-mpo 5779 df-pnf 7802 df-mnf 7803 df-xr 7804 df-ltxr 7805 df-le 7806 df-sub 7935 df-neg 7936 df-reap 8337 df-ap 8344 df-inn 8721 df-2 8779 df-n0 8978 df-z 9055 |
This theorem is referenced by: (None) |
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