Metamath Proof Explorer |
< Previous
Next >
Nearby theorems |
||
Mirrors > Home > MPE Home > Th. List > rddif | Structured version Visualization version GIF version |
Description: The difference between a real number and its nearest integer is less than or equal to one half. (Contributed by Jeff Madsen, 2-Sep-2009.) (Proof shortened by Mario Carneiro, 14-Sep-2015.) |
Ref | Expression |
---|---|
rddif | ⊢ (𝐴 ∈ ℝ → (abs‘((⌊‘(𝐴 + (1 / 2))) − 𝐴)) ≤ (1 / 2)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | halfcn 11853 | . . . . . . . 8 ⊢ (1 / 2) ∈ ℂ | |
2 | 1 | 2timesi 11776 | . . . . . . 7 ⊢ (2 · (1 / 2)) = ((1 / 2) + (1 / 2)) |
3 | 2cn 11713 | . . . . . . . 8 ⊢ 2 ∈ ℂ | |
4 | 2ne0 11742 | . . . . . . . 8 ⊢ 2 ≠ 0 | |
5 | 3, 4 | recidi 11371 | . . . . . . 7 ⊢ (2 · (1 / 2)) = 1 |
6 | 2, 5 | eqtr3i 2846 | . . . . . 6 ⊢ ((1 / 2) + (1 / 2)) = 1 |
7 | 6 | oveq2i 7167 | . . . . 5 ⊢ ((𝐴 − (1 / 2)) + ((1 / 2) + (1 / 2))) = ((𝐴 − (1 / 2)) + 1) |
8 | recn 10627 | . . . . . 6 ⊢ (𝐴 ∈ ℝ → 𝐴 ∈ ℂ) | |
9 | 1 | a1i 11 | . . . . . 6 ⊢ (𝐴 ∈ ℝ → (1 / 2) ∈ ℂ) |
10 | 8, 9, 9 | nppcan3d 11024 | . . . . 5 ⊢ (𝐴 ∈ ℝ → ((𝐴 − (1 / 2)) + ((1 / 2) + (1 / 2))) = (𝐴 + (1 / 2))) |
11 | 7, 10 | syl5eqr 2870 | . . . 4 ⊢ (𝐴 ∈ ℝ → ((𝐴 − (1 / 2)) + 1) = (𝐴 + (1 / 2))) |
12 | halfre 11852 | . . . . . 6 ⊢ (1 / 2) ∈ ℝ | |
13 | readdcl 10620 | . . . . . 6 ⊢ ((𝐴 ∈ ℝ ∧ (1 / 2) ∈ ℝ) → (𝐴 + (1 / 2)) ∈ ℝ) | |
14 | 12, 13 | mpan2 689 | . . . . 5 ⊢ (𝐴 ∈ ℝ → (𝐴 + (1 / 2)) ∈ ℝ) |
15 | fllep1 13172 | . . . . 5 ⊢ ((𝐴 + (1 / 2)) ∈ ℝ → (𝐴 + (1 / 2)) ≤ ((⌊‘(𝐴 + (1 / 2))) + 1)) | |
16 | 14, 15 | syl 17 | . . . 4 ⊢ (𝐴 ∈ ℝ → (𝐴 + (1 / 2)) ≤ ((⌊‘(𝐴 + (1 / 2))) + 1)) |
17 | 11, 16 | eqbrtrd 5088 | . . 3 ⊢ (𝐴 ∈ ℝ → ((𝐴 − (1 / 2)) + 1) ≤ ((⌊‘(𝐴 + (1 / 2))) + 1)) |
18 | resubcl 10950 | . . . . 5 ⊢ ((𝐴 ∈ ℝ ∧ (1 / 2) ∈ ℝ) → (𝐴 − (1 / 2)) ∈ ℝ) | |
19 | 12, 18 | mpan2 689 | . . . 4 ⊢ (𝐴 ∈ ℝ → (𝐴 − (1 / 2)) ∈ ℝ) |
20 | reflcl 13167 | . . . . 5 ⊢ ((𝐴 + (1 / 2)) ∈ ℝ → (⌊‘(𝐴 + (1 / 2))) ∈ ℝ) | |
21 | 14, 20 | syl 17 | . . . 4 ⊢ (𝐴 ∈ ℝ → (⌊‘(𝐴 + (1 / 2))) ∈ ℝ) |
22 | 1red 10642 | . . . 4 ⊢ (𝐴 ∈ ℝ → 1 ∈ ℝ) | |
23 | 19, 21, 22 | leadd1d 11234 | . . 3 ⊢ (𝐴 ∈ ℝ → ((𝐴 − (1 / 2)) ≤ (⌊‘(𝐴 + (1 / 2))) ↔ ((𝐴 − (1 / 2)) + 1) ≤ ((⌊‘(𝐴 + (1 / 2))) + 1))) |
24 | 17, 23 | mpbird 259 | . 2 ⊢ (𝐴 ∈ ℝ → (𝐴 − (1 / 2)) ≤ (⌊‘(𝐴 + (1 / 2)))) |
25 | flle 13170 | . . 3 ⊢ ((𝐴 + (1 / 2)) ∈ ℝ → (⌊‘(𝐴 + (1 / 2))) ≤ (𝐴 + (1 / 2))) | |
26 | 14, 25 | syl 17 | . 2 ⊢ (𝐴 ∈ ℝ → (⌊‘(𝐴 + (1 / 2))) ≤ (𝐴 + (1 / 2))) |
27 | id 22 | . . 3 ⊢ (𝐴 ∈ ℝ → 𝐴 ∈ ℝ) | |
28 | 12 | a1i 11 | . . 3 ⊢ (𝐴 ∈ ℝ → (1 / 2) ∈ ℝ) |
29 | absdifle 14678 | . . 3 ⊢ (((⌊‘(𝐴 + (1 / 2))) ∈ ℝ ∧ 𝐴 ∈ ℝ ∧ (1 / 2) ∈ ℝ) → ((abs‘((⌊‘(𝐴 + (1 / 2))) − 𝐴)) ≤ (1 / 2) ↔ ((𝐴 − (1 / 2)) ≤ (⌊‘(𝐴 + (1 / 2))) ∧ (⌊‘(𝐴 + (1 / 2))) ≤ (𝐴 + (1 / 2))))) | |
30 | 21, 27, 28, 29 | syl3anc 1367 | . 2 ⊢ (𝐴 ∈ ℝ → ((abs‘((⌊‘(𝐴 + (1 / 2))) − 𝐴)) ≤ (1 / 2) ↔ ((𝐴 − (1 / 2)) ≤ (⌊‘(𝐴 + (1 / 2))) ∧ (⌊‘(𝐴 + (1 / 2))) ≤ (𝐴 + (1 / 2))))) |
31 | 24, 26, 30 | mpbir2and 711 | 1 ⊢ (𝐴 ∈ ℝ → (abs‘((⌊‘(𝐴 + (1 / 2))) − 𝐴)) ≤ (1 / 2)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 208 ∧ wa 398 ∈ wcel 2114 class class class wbr 5066 ‘cfv 6355 (class class class)co 7156 ℂcc 10535 ℝcr 10536 1c1 10538 + caddc 10540 · cmul 10542 ≤ cle 10676 − cmin 10870 / cdiv 11297 2c2 11693 ⌊cfl 13161 abscabs 14593 |
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 ax-pre-sup 10615 |
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-2nd 7690 df-wrecs 7947 df-recs 8008 df-rdg 8046 df-er 8289 df-en 8510 df-dom 8511 df-sdom 8512 df-sup 8906 df-inf 8907 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-n0 11899 df-z 11983 df-uz 12245 df-rp 12391 df-fl 13163 df-seq 13371 df-exp 13431 df-cj 14458 df-re 14459 df-im 14460 df-sqrt 14594 df-abs 14595 |
This theorem is referenced by: absrdbnd 14701 rddif2 33816 dnibndlem11 33827 knoppcnlem4 33835 cntotbnd 35089 |
Copyright terms: Public domain | W3C validator |