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Mirrors > Home > ILE Home > Th. List > btwnz | GIF version |
Description: Any real number can be sandwiched between two integers. Exercise 2 of [Apostol] p. 28. (Contributed by NM, 10-Nov-2004.) |
Ref | Expression |
---|---|
btwnz | ⊢ (𝐴 ∈ ℝ → (∃𝑥 ∈ ℤ 𝑥 < 𝐴 ∧ ∃𝑦 ∈ ℤ 𝐴 < 𝑦)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | renegcl 8150 | . . . 4 ⊢ (𝐴 ∈ ℝ → -𝐴 ∈ ℝ) | |
2 | arch 9102 | . . . 4 ⊢ (-𝐴 ∈ ℝ → ∃𝑧 ∈ ℕ -𝐴 < 𝑧) | |
3 | 1, 2 | syl 14 | . . 3 ⊢ (𝐴 ∈ ℝ → ∃𝑧 ∈ ℕ -𝐴 < 𝑧) |
4 | nnre 8855 | . . . . . . . 8 ⊢ (𝑧 ∈ ℕ → 𝑧 ∈ ℝ) | |
5 | ltnegcon1 8352 | . . . . . . . . 9 ⊢ ((𝐴 ∈ ℝ ∧ 𝑧 ∈ ℝ) → (-𝐴 < 𝑧 ↔ -𝑧 < 𝐴)) | |
6 | 5 | ex 114 | . . . . . . . 8 ⊢ (𝐴 ∈ ℝ → (𝑧 ∈ ℝ → (-𝐴 < 𝑧 ↔ -𝑧 < 𝐴))) |
7 | 4, 6 | syl5 32 | . . . . . . 7 ⊢ (𝐴 ∈ ℝ → (𝑧 ∈ ℕ → (-𝐴 < 𝑧 ↔ -𝑧 < 𝐴))) |
8 | 7 | pm5.32d 446 | . . . . . 6 ⊢ (𝐴 ∈ ℝ → ((𝑧 ∈ ℕ ∧ -𝐴 < 𝑧) ↔ (𝑧 ∈ ℕ ∧ -𝑧 < 𝐴))) |
9 | nnnegz 9185 | . . . . . . 7 ⊢ (𝑧 ∈ ℕ → -𝑧 ∈ ℤ) | |
10 | breq1 3979 | . . . . . . . 8 ⊢ (𝑥 = -𝑧 → (𝑥 < 𝐴 ↔ -𝑧 < 𝐴)) | |
11 | 10 | rspcev 2825 | . . . . . . 7 ⊢ ((-𝑧 ∈ ℤ ∧ -𝑧 < 𝐴) → ∃𝑥 ∈ ℤ 𝑥 < 𝐴) |
12 | 9, 11 | sylan 281 | . . . . . 6 ⊢ ((𝑧 ∈ ℕ ∧ -𝑧 < 𝐴) → ∃𝑥 ∈ ℤ 𝑥 < 𝐴) |
13 | 8, 12 | syl6bi 162 | . . . . 5 ⊢ (𝐴 ∈ ℝ → ((𝑧 ∈ ℕ ∧ -𝐴 < 𝑧) → ∃𝑥 ∈ ℤ 𝑥 < 𝐴)) |
14 | 13 | expd 256 | . . . 4 ⊢ (𝐴 ∈ ℝ → (𝑧 ∈ ℕ → (-𝐴 < 𝑧 → ∃𝑥 ∈ ℤ 𝑥 < 𝐴))) |
15 | 14 | rexlimdv 2580 | . . 3 ⊢ (𝐴 ∈ ℝ → (∃𝑧 ∈ ℕ -𝐴 < 𝑧 → ∃𝑥 ∈ ℤ 𝑥 < 𝐴)) |
16 | 3, 15 | mpd 13 | . 2 ⊢ (𝐴 ∈ ℝ → ∃𝑥 ∈ ℤ 𝑥 < 𝐴) |
17 | arch 9102 | . . 3 ⊢ (𝐴 ∈ ℝ → ∃𝑦 ∈ ℕ 𝐴 < 𝑦) | |
18 | nnz 9201 | . . . . 5 ⊢ (𝑦 ∈ ℕ → 𝑦 ∈ ℤ) | |
19 | 18 | anim1i 338 | . . . 4 ⊢ ((𝑦 ∈ ℕ ∧ 𝐴 < 𝑦) → (𝑦 ∈ ℤ ∧ 𝐴 < 𝑦)) |
20 | 19 | reximi2 2560 | . . 3 ⊢ (∃𝑦 ∈ ℕ 𝐴 < 𝑦 → ∃𝑦 ∈ ℤ 𝐴 < 𝑦) |
21 | 17, 20 | syl 14 | . 2 ⊢ (𝐴 ∈ ℝ → ∃𝑦 ∈ ℤ 𝐴 < 𝑦) |
22 | 16, 21 | jca 304 | 1 ⊢ (𝐴 ∈ ℝ → (∃𝑥 ∈ ℤ 𝑥 < 𝐴 ∧ ∃𝑦 ∈ ℤ 𝐴 < 𝑦)) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ∧ wa 103 ↔ wb 104 ∈ wcel 2135 ∃wrex 2443 class class class wbr 3976 ℝcr 7743 < clt 7924 -cneg 8061 ℕcn 8848 ℤcz 9182 |
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 604 ax-in2 605 ax-io 699 ax-5 1434 ax-7 1435 ax-gen 1436 ax-ie1 1480 ax-ie2 1481 ax-8 1491 ax-10 1492 ax-11 1493 ax-i12 1494 ax-bndl 1496 ax-4 1497 ax-17 1513 ax-i9 1517 ax-ial 1521 ax-i5r 1522 ax-13 2137 ax-14 2138 ax-ext 2146 ax-sep 4094 ax-pow 4147 ax-pr 4181 ax-un 4405 ax-setind 4508 ax-cnex 7835 ax-resscn 7836 ax-1cn 7837 ax-1re 7838 ax-icn 7839 ax-addcl 7840 ax-addrcl 7841 ax-mulcl 7842 ax-addcom 7844 ax-addass 7846 ax-distr 7848 ax-i2m1 7849 ax-0lt1 7850 ax-0id 7852 ax-rnegex 7853 ax-cnre 7855 ax-pre-ltirr 7856 ax-pre-ltwlin 7857 ax-pre-lttrn 7858 ax-pre-ltadd 7860 ax-arch 7863 |
This theorem depends on definitions: df-bi 116 df-3or 968 df-3an 969 df-tru 1345 df-fal 1348 df-nf 1448 df-sb 1750 df-eu 2016 df-mo 2017 df-clab 2151 df-cleq 2157 df-clel 2160 df-nfc 2295 df-ne 2335 df-nel 2430 df-ral 2447 df-rex 2448 df-reu 2449 df-rab 2451 df-v 2723 df-sbc 2947 df-dif 3113 df-un 3115 df-in 3117 df-ss 3124 df-pw 3555 df-sn 3576 df-pr 3577 df-op 3579 df-uni 3784 df-int 3819 df-br 3977 df-opab 4038 df-id 4265 df-xp 4604 df-rel 4605 df-cnv 4606 df-co 4607 df-dm 4608 df-iota 5147 df-fun 5184 df-fv 5190 df-riota 5792 df-ov 5839 df-oprab 5840 df-mpo 5841 df-pnf 7926 df-mnf 7927 df-xr 7928 df-ltxr 7929 df-le 7930 df-sub 8062 df-neg 8063 df-inn 8849 df-z 9183 |
This theorem is referenced by: lbzbi 9545 exbtwnzlemex 10175 rebtwn2z 10180 |
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