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Mirrors > Home > ILE Home > Th. List > zneo | GIF version |
Description: No even integer equals an odd integer (i.e. no integer can be both even and odd). Exercise 10(a) of [Apostol] p. 28. (Contributed by NM, 31-Jul-2004.) (Proof shortened by Mario Carneiro, 18-May-2014.) |
Ref | Expression |
---|---|
zneo | ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → (2 · 𝐴) ≠ ((2 · 𝐵) + 1)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | halfnz 8443 | . . 3 ⊢ ¬ (1 / 2) ∈ ℤ | |
2 | 2cn 8110 | . . . . . . 7 ⊢ 2 ∈ ℂ | |
3 | zcn 8356 | . . . . . . . 8 ⊢ (𝐴 ∈ ℤ → 𝐴 ∈ ℂ) | |
4 | 3 | adantr 270 | . . . . . . 7 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → 𝐴 ∈ ℂ) |
5 | mulcl 7100 | . . . . . . 7 ⊢ ((2 ∈ ℂ ∧ 𝐴 ∈ ℂ) → (2 · 𝐴) ∈ ℂ) | |
6 | 2, 4, 5 | sylancr 405 | . . . . . 6 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → (2 · 𝐴) ∈ ℂ) |
7 | zcn 8356 | . . . . . . . 8 ⊢ (𝐵 ∈ ℤ → 𝐵 ∈ ℂ) | |
8 | 7 | adantl 271 | . . . . . . 7 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → 𝐵 ∈ ℂ) |
9 | mulcl 7100 | . . . . . . 7 ⊢ ((2 ∈ ℂ ∧ 𝐵 ∈ ℂ) → (2 · 𝐵) ∈ ℂ) | |
10 | 2, 8, 9 | sylancr 405 | . . . . . 6 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → (2 · 𝐵) ∈ ℂ) |
11 | 1cnd 7135 | . . . . . 6 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → 1 ∈ ℂ) | |
12 | 6, 10, 11 | subaddd 7437 | . . . . 5 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → (((2 · 𝐴) − (2 · 𝐵)) = 1 ↔ ((2 · 𝐵) + 1) = (2 · 𝐴))) |
13 | 2 | a1i 9 | . . . . . . . . . 10 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → 2 ∈ ℂ) |
14 | 13, 4, 8 | subdid 7518 | . . . . . . . . 9 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → (2 · (𝐴 − 𝐵)) = ((2 · 𝐴) − (2 · 𝐵))) |
15 | 14 | oveq1d 5547 | . . . . . . . 8 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → ((2 · (𝐴 − 𝐵)) / 2) = (((2 · 𝐴) − (2 · 𝐵)) / 2)) |
16 | zsubcl 8392 | . . . . . . . . . 10 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → (𝐴 − 𝐵) ∈ ℤ) | |
17 | zcn 8356 | . . . . . . . . . 10 ⊢ ((𝐴 − 𝐵) ∈ ℤ → (𝐴 − 𝐵) ∈ ℂ) | |
18 | 16, 17 | syl 14 | . . . . . . . . 9 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → (𝐴 − 𝐵) ∈ ℂ) |
19 | 2ap0 8132 | . . . . . . . . . 10 ⊢ 2 # 0 | |
20 | 19 | a1i 9 | . . . . . . . . 9 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → 2 # 0) |
21 | 18, 13, 20 | divcanap3d 7882 | . . . . . . . 8 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → ((2 · (𝐴 − 𝐵)) / 2) = (𝐴 − 𝐵)) |
22 | 15, 21 | eqtr3d 2115 | . . . . . . 7 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → (((2 · 𝐴) − (2 · 𝐵)) / 2) = (𝐴 − 𝐵)) |
23 | 22, 16 | eqeltrd 2155 | . . . . . 6 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → (((2 · 𝐴) − (2 · 𝐵)) / 2) ∈ ℤ) |
24 | oveq1 5539 | . . . . . . 7 ⊢ (((2 · 𝐴) − (2 · 𝐵)) = 1 → (((2 · 𝐴) − (2 · 𝐵)) / 2) = (1 / 2)) | |
25 | 24 | eleq1d 2147 | . . . . . 6 ⊢ (((2 · 𝐴) − (2 · 𝐵)) = 1 → ((((2 · 𝐴) − (2 · 𝐵)) / 2) ∈ ℤ ↔ (1 / 2) ∈ ℤ)) |
26 | 23, 25 | syl5ibcom 153 | . . . . 5 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → (((2 · 𝐴) − (2 · 𝐵)) = 1 → (1 / 2) ∈ ℤ)) |
27 | 12, 26 | sylbird 168 | . . . 4 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → (((2 · 𝐵) + 1) = (2 · 𝐴) → (1 / 2) ∈ ℤ)) |
28 | 27 | necon3bd 2288 | . . 3 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → (¬ (1 / 2) ∈ ℤ → ((2 · 𝐵) + 1) ≠ (2 · 𝐴))) |
29 | 1, 28 | mpi 15 | . 2 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → ((2 · 𝐵) + 1) ≠ (2 · 𝐴)) |
30 | 29 | necomd 2331 | 1 ⊢ ((𝐴 ∈ ℤ ∧ 𝐵 ∈ ℤ) → (2 · 𝐴) ≠ ((2 · 𝐵) + 1)) |
Colors of variables: wff set class |
Syntax hints: ¬ wn 3 → wi 4 ∧ wa 102 = wceq 1284 ∈ wcel 1433 ≠ wne 2245 class class class wbr 3785 (class class class)co 5532 ℂcc 6979 0cc0 6981 1c1 6982 + caddc 6984 · cmul 6986 − cmin 7279 # cap 7681 / cdiv 7760 2c2 8089 ℤcz 8351 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 104 ax-ia2 105 ax-ia3 106 ax-in1 576 ax-in2 577 ax-io 662 ax-5 1376 ax-7 1377 ax-gen 1378 ax-ie1 1422 ax-ie2 1423 ax-8 1435 ax-10 1436 ax-11 1437 ax-i12 1438 ax-bndl 1439 ax-4 1440 ax-13 1444 ax-14 1445 ax-17 1459 ax-i9 1463 ax-ial 1467 ax-i5r 1468 ax-ext 2063 ax-sep 3896 ax-pow 3948 ax-pr 3964 ax-un 4188 ax-setind 4280 ax-cnex 7067 ax-resscn 7068 ax-1cn 7069 ax-1re 7070 ax-icn 7071 ax-addcl 7072 ax-addrcl 7073 ax-mulcl 7074 ax-mulrcl 7075 ax-addcom 7076 ax-mulcom 7077 ax-addass 7078 ax-mulass 7079 ax-distr 7080 ax-i2m1 7081 ax-0lt1 7082 ax-1rid 7083 ax-0id 7084 ax-rnegex 7085 ax-precex 7086 ax-cnre 7087 ax-pre-ltirr 7088 ax-pre-ltwlin 7089 ax-pre-lttrn 7090 ax-pre-apti 7091 ax-pre-ltadd 7092 ax-pre-mulgt0 7093 ax-pre-mulext 7094 |
This theorem depends on definitions: df-bi 115 df-3or 920 df-3an 921 df-tru 1287 df-fal 1290 df-nf 1390 df-sb 1686 df-eu 1944 df-mo 1945 df-clab 2068 df-cleq 2074 df-clel 2077 df-nfc 2208 df-ne 2246 df-nel 2340 df-ral 2353 df-rex 2354 df-reu 2355 df-rmo 2356 df-rab 2357 df-v 2603 df-sbc 2816 df-dif 2975 df-un 2977 df-in 2979 df-ss 2986 df-pw 3384 df-sn 3404 df-pr 3405 df-op 3407 df-uni 3602 df-int 3637 df-br 3786 df-opab 3840 df-id 4048 df-po 4051 df-iso 4052 df-xp 4369 df-rel 4370 df-cnv 4371 df-co 4372 df-dm 4373 df-iota 4887 df-fun 4924 df-fv 4930 df-riota 5488 df-ov 5535 df-oprab 5536 df-mpt2 5537 df-pnf 7155 df-mnf 7156 df-xr 7157 df-ltxr 7158 df-le 7159 df-sub 7281 df-neg 7282 df-reap 7675 df-ap 7682 df-div 7761 df-inn 8040 df-2 8098 df-n0 8289 df-z 8352 |
This theorem is referenced by: nneo 8450 zeo2 8453 |
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