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Mathbox for Alexander van der Vekens |
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Mirrors > Home > MPE Home > Th. List > Mathboxes > zofldiv2ALTV | Structured version Visualization version GIF version |
Description: The floor of an odd numer divided by 2 is equal to the odd number first decreased by 1 and then divided by 2. (Contributed by AV, 7-Jun-2020.) (Revised by AV, 18-Jun-2020.) |
Ref | Expression |
---|---|
zofldiv2ALTV | ⊢ (𝑁 ∈ Odd → (⌊‘(𝑁 / 2)) = ((𝑁 − 1) / 2)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | oddz 47108 | . . . . 5 ⊢ (𝑁 ∈ Odd → 𝑁 ∈ ℤ) | |
2 | 1 | zcnd 12700 | . . . 4 ⊢ (𝑁 ∈ Odd → 𝑁 ∈ ℂ) |
3 | npcan1 11671 | . . . . . . 7 ⊢ (𝑁 ∈ ℂ → ((𝑁 − 1) + 1) = 𝑁) | |
4 | 3 | eqcomd 2731 | . . . . . 6 ⊢ (𝑁 ∈ ℂ → 𝑁 = ((𝑁 − 1) + 1)) |
5 | 4 | oveq1d 7434 | . . . . 5 ⊢ (𝑁 ∈ ℂ → (𝑁 / 2) = (((𝑁 − 1) + 1) / 2)) |
6 | peano2cnm 11558 | . . . . . 6 ⊢ (𝑁 ∈ ℂ → (𝑁 − 1) ∈ ℂ) | |
7 | 1cnd 11241 | . . . . . 6 ⊢ (𝑁 ∈ ℂ → 1 ∈ ℂ) | |
8 | 2cnne0 12455 | . . . . . . 7 ⊢ (2 ∈ ℂ ∧ 2 ≠ 0) | |
9 | 8 | a1i 11 | . . . . . 6 ⊢ (𝑁 ∈ ℂ → (2 ∈ ℂ ∧ 2 ≠ 0)) |
10 | divdir 11930 | . . . . . 6 ⊢ (((𝑁 − 1) ∈ ℂ ∧ 1 ∈ ℂ ∧ (2 ∈ ℂ ∧ 2 ≠ 0)) → (((𝑁 − 1) + 1) / 2) = (((𝑁 − 1) / 2) + (1 / 2))) | |
11 | 6, 7, 9, 10 | syl3anc 1368 | . . . . 5 ⊢ (𝑁 ∈ ℂ → (((𝑁 − 1) + 1) / 2) = (((𝑁 − 1) / 2) + (1 / 2))) |
12 | 5, 11 | eqtrd 2765 | . . . 4 ⊢ (𝑁 ∈ ℂ → (𝑁 / 2) = (((𝑁 − 1) / 2) + (1 / 2))) |
13 | 2, 12 | syl 17 | . . 3 ⊢ (𝑁 ∈ Odd → (𝑁 / 2) = (((𝑁 − 1) / 2) + (1 / 2))) |
14 | 13 | fveq2d 6900 | . 2 ⊢ (𝑁 ∈ Odd → (⌊‘(𝑁 / 2)) = (⌊‘(((𝑁 − 1) / 2) + (1 / 2)))) |
15 | halfge0 12462 | . . . 4 ⊢ 0 ≤ (1 / 2) | |
16 | halflt1 12463 | . . . 4 ⊢ (1 / 2) < 1 | |
17 | 15, 16 | pm3.2i 469 | . . 3 ⊢ (0 ≤ (1 / 2) ∧ (1 / 2) < 1) |
18 | oddm1div2z 47111 | . . . 4 ⊢ (𝑁 ∈ Odd → ((𝑁 − 1) / 2) ∈ ℤ) | |
19 | halfre 12459 | . . . 4 ⊢ (1 / 2) ∈ ℝ | |
20 | flbi2 13818 | . . . 4 ⊢ ((((𝑁 − 1) / 2) ∈ ℤ ∧ (1 / 2) ∈ ℝ) → ((⌊‘(((𝑁 − 1) / 2) + (1 / 2))) = ((𝑁 − 1) / 2) ↔ (0 ≤ (1 / 2) ∧ (1 / 2) < 1))) | |
21 | 18, 19, 20 | sylancl 584 | . . 3 ⊢ (𝑁 ∈ Odd → ((⌊‘(((𝑁 − 1) / 2) + (1 / 2))) = ((𝑁 − 1) / 2) ↔ (0 ≤ (1 / 2) ∧ (1 / 2) < 1))) |
22 | 17, 21 | mpbiri 257 | . 2 ⊢ (𝑁 ∈ Odd → (⌊‘(((𝑁 − 1) / 2) + (1 / 2))) = ((𝑁 − 1) / 2)) |
23 | 14, 22 | eqtrd 2765 | 1 ⊢ (𝑁 ∈ Odd → (⌊‘(𝑁 / 2)) = ((𝑁 − 1) / 2)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 205 ∧ wa 394 = wceq 1533 ∈ wcel 2098 ≠ wne 2929 class class class wbr 5149 ‘cfv 6549 (class class class)co 7419 ℂcc 11138 ℝcr 11139 0cc0 11140 1c1 11141 + caddc 11143 < clt 11280 ≤ cle 11281 − cmin 11476 / cdiv 11903 2c2 12300 ℤcz 12591 ⌊cfl 13791 Odd codd 47102 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1789 ax-4 1803 ax-5 1905 ax-6 1963 ax-7 2003 ax-8 2100 ax-9 2108 ax-10 2129 ax-11 2146 ax-12 2166 ax-ext 2696 ax-sep 5300 ax-nul 5307 ax-pow 5365 ax-pr 5429 ax-un 7741 ax-cnex 11196 ax-resscn 11197 ax-1cn 11198 ax-icn 11199 ax-addcl 11200 ax-addrcl 11201 ax-mulcl 11202 ax-mulrcl 11203 ax-mulcom 11204 ax-addass 11205 ax-mulass 11206 ax-distr 11207 ax-i2m1 11208 ax-1ne0 11209 ax-1rid 11210 ax-rnegex 11211 ax-rrecex 11212 ax-cnre 11213 ax-pre-lttri 11214 ax-pre-lttrn 11215 ax-pre-ltadd 11216 ax-pre-mulgt0 11217 ax-pre-sup 11218 |
This theorem depends on definitions: df-bi 206 df-an 395 df-or 846 df-3or 1085 df-3an 1086 df-tru 1536 df-fal 1546 df-ex 1774 df-nf 1778 df-sb 2060 df-mo 2528 df-eu 2557 df-clab 2703 df-cleq 2717 df-clel 2802 df-nfc 2877 df-ne 2930 df-nel 3036 df-ral 3051 df-rex 3060 df-rmo 3363 df-reu 3364 df-rab 3419 df-v 3463 df-sbc 3774 df-csb 3890 df-dif 3947 df-un 3949 df-in 3951 df-ss 3961 df-pss 3964 df-nul 4323 df-if 4531 df-pw 4606 df-sn 4631 df-pr 4633 df-op 4637 df-uni 4910 df-iun 4999 df-br 5150 df-opab 5212 df-mpt 5233 df-tr 5267 df-id 5576 df-eprel 5582 df-po 5590 df-so 5591 df-fr 5633 df-we 5635 df-xp 5684 df-rel 5685 df-cnv 5686 df-co 5687 df-dm 5688 df-rn 5689 df-res 5690 df-ima 5691 df-pred 6307 df-ord 6374 df-on 6375 df-lim 6376 df-suc 6377 df-iota 6501 df-fun 6551 df-fn 6552 df-f 6553 df-f1 6554 df-fo 6555 df-f1o 6556 df-fv 6557 df-riota 7375 df-ov 7422 df-oprab 7423 df-mpo 7424 df-om 7872 df-2nd 7995 df-frecs 8287 df-wrecs 8318 df-recs 8392 df-rdg 8431 df-er 8725 df-en 8965 df-dom 8966 df-sdom 8967 df-sup 9467 df-inf 9468 df-pnf 11282 df-mnf 11283 df-xr 11284 df-ltxr 11285 df-le 11286 df-sub 11478 df-neg 11479 df-div 11904 df-nn 12246 df-2 12308 df-n0 12506 df-z 12592 df-uz 12856 df-fl 13793 df-odd 47104 |
This theorem is referenced by: oddflALTV 47140 |
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