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Mirrors > Home > MPE Home > Th. List > zob | Structured version Visualization version GIF version |
Description: Alternate characterizations of an odd number. (Contributed by AV, 7-Jun-2020.) |
Ref | Expression |
---|---|
zob | ⊢ (𝑁 ∈ ℤ → (((𝑁 + 1) / 2) ∈ ℤ ↔ ((𝑁 − 1) / 2) ∈ ℤ)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | peano2zm 12476 | . . 3 ⊢ (((𝑁 + 1) / 2) ∈ ℤ → (((𝑁 + 1) / 2) − 1) ∈ ℤ) | |
2 | peano2z 12474 | . . . 4 ⊢ ((((𝑁 + 1) / 2) − 1) ∈ ℤ → ((((𝑁 + 1) / 2) − 1) + 1) ∈ ℤ) | |
3 | peano2z 12474 | . . . . . . . . 9 ⊢ (𝑁 ∈ ℤ → (𝑁 + 1) ∈ ℤ) | |
4 | 3 | zcnd 12540 | . . . . . . . 8 ⊢ (𝑁 ∈ ℤ → (𝑁 + 1) ∈ ℂ) |
5 | 4 | halfcld 12331 | . . . . . . 7 ⊢ (𝑁 ∈ ℤ → ((𝑁 + 1) / 2) ∈ ℂ) |
6 | npcan1 11513 | . . . . . . 7 ⊢ (((𝑁 + 1) / 2) ∈ ℂ → ((((𝑁 + 1) / 2) − 1) + 1) = ((𝑁 + 1) / 2)) | |
7 | 5, 6 | syl 17 | . . . . . 6 ⊢ (𝑁 ∈ ℤ → ((((𝑁 + 1) / 2) − 1) + 1) = ((𝑁 + 1) / 2)) |
8 | 7 | eqcomd 2743 | . . . . 5 ⊢ (𝑁 ∈ ℤ → ((𝑁 + 1) / 2) = ((((𝑁 + 1) / 2) − 1) + 1)) |
9 | 8 | eleq1d 2822 | . . . 4 ⊢ (𝑁 ∈ ℤ → (((𝑁 + 1) / 2) ∈ ℤ ↔ ((((𝑁 + 1) / 2) − 1) + 1) ∈ ℤ)) |
10 | 2, 9 | syl5ibr 245 | . . 3 ⊢ (𝑁 ∈ ℤ → ((((𝑁 + 1) / 2) − 1) ∈ ℤ → ((𝑁 + 1) / 2) ∈ ℤ)) |
11 | 1, 10 | impbid2 225 | . 2 ⊢ (𝑁 ∈ ℤ → (((𝑁 + 1) / 2) ∈ ℤ ↔ (((𝑁 + 1) / 2) − 1) ∈ ℤ)) |
12 | zcn 12437 | . . . 4 ⊢ (𝑁 ∈ ℤ → 𝑁 ∈ ℂ) | |
13 | xp1d2m1eqxm1d2 12340 | . . . 4 ⊢ (𝑁 ∈ ℂ → (((𝑁 + 1) / 2) − 1) = ((𝑁 − 1) / 2)) | |
14 | 12, 13 | syl 17 | . . 3 ⊢ (𝑁 ∈ ℤ → (((𝑁 + 1) / 2) − 1) = ((𝑁 − 1) / 2)) |
15 | 14 | eleq1d 2822 | . 2 ⊢ (𝑁 ∈ ℤ → ((((𝑁 + 1) / 2) − 1) ∈ ℤ ↔ ((𝑁 − 1) / 2) ∈ ℤ)) |
16 | 11, 15 | bitrd 278 | 1 ⊢ (𝑁 ∈ ℤ → (((𝑁 + 1) / 2) ∈ ℤ ↔ ((𝑁 − 1) / 2) ∈ ℤ)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 205 = wceq 1541 ∈ wcel 2106 (class class class)co 7349 ℂcc 10982 1c1 10985 + caddc 10987 − cmin 11318 / cdiv 11745 2c2 12141 ℤcz 12432 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1797 ax-4 1811 ax-5 1913 ax-6 1971 ax-7 2011 ax-8 2108 ax-9 2116 ax-10 2137 ax-11 2154 ax-12 2171 ax-ext 2708 ax-sep 5254 ax-nul 5261 ax-pow 5318 ax-pr 5382 ax-un 7662 ax-resscn 11041 ax-1cn 11042 ax-icn 11043 ax-addcl 11044 ax-addrcl 11045 ax-mulcl 11046 ax-mulrcl 11047 ax-mulcom 11048 ax-addass 11049 ax-mulass 11050 ax-distr 11051 ax-i2m1 11052 ax-1ne0 11053 ax-1rid 11054 ax-rnegex 11055 ax-rrecex 11056 ax-cnre 11057 ax-pre-lttri 11058 ax-pre-lttrn 11059 ax-pre-ltadd 11060 ax-pre-mulgt0 11061 |
This theorem depends on definitions: df-bi 206 df-an 397 df-or 846 df-3or 1088 df-3an 1089 df-tru 1544 df-fal 1554 df-ex 1782 df-nf 1786 df-sb 2068 df-mo 2539 df-eu 2568 df-clab 2715 df-cleq 2729 df-clel 2815 df-nfc 2887 df-ne 2942 df-nel 3048 df-ral 3063 df-rex 3072 df-rmo 3351 df-reu 3352 df-rab 3406 df-v 3445 df-sbc 3738 df-csb 3854 df-dif 3911 df-un 3913 df-in 3915 df-ss 3925 df-pss 3927 df-nul 4281 df-if 4485 df-pw 4560 df-sn 4585 df-pr 4587 df-op 4591 df-uni 4864 df-iun 4954 df-br 5104 df-opab 5166 df-mpt 5187 df-tr 5221 df-id 5528 df-eprel 5534 df-po 5542 df-so 5543 df-fr 5585 df-we 5587 df-xp 5636 df-rel 5637 df-cnv 5638 df-co 5639 df-dm 5640 df-rn 5641 df-res 5642 df-ima 5643 df-pred 6249 df-ord 6316 df-on 6317 df-lim 6318 df-suc 6319 df-iota 6443 df-fun 6493 df-fn 6494 df-f 6495 df-f1 6496 df-fo 6497 df-f1o 6498 df-fv 6499 df-riota 7305 df-ov 7352 df-oprab 7353 df-mpo 7354 df-om 7793 df-2nd 7912 df-frecs 8179 df-wrecs 8210 df-recs 8284 df-rdg 8323 df-er 8581 df-en 8817 df-dom 8818 df-sdom 8819 df-pnf 11124 df-mnf 11125 df-xr 11126 df-ltxr 11127 df-le 11128 df-sub 11320 df-neg 11321 df-div 11746 df-nn 12087 df-2 12149 df-n0 12347 df-z 12433 |
This theorem is referenced by: oddm1d2 16176 oddm1div2z 45575 isodd2 45576 zofldiv2 46366 dignn0flhalflem2 46451 nn0sumshdiglemB 46455 |
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