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Mirrors > Home > MPE Home > Th. List > Mathboxes > dfeven4 | Structured version Visualization version GIF version |
Description: Alternate definition for even numbers. (Contributed by AV, 18-Jun-2020.) |
Ref | Expression |
---|---|
dfeven4 | ⊢ Even = {𝑧 ∈ ℤ ∣ ∃𝑖 ∈ ℤ 𝑧 = (2 · 𝑖)} |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-even 45047 | . 2 ⊢ Even = {𝑧 ∈ ℤ ∣ (𝑧 / 2) ∈ ℤ} | |
2 | simpr 485 | . . . . . 6 ⊢ ((𝑧 ∈ ℤ ∧ (𝑧 / 2) ∈ ℤ) → (𝑧 / 2) ∈ ℤ) | |
3 | oveq2 7279 | . . . . . . . 8 ⊢ (𝑖 = (𝑧 / 2) → (2 · 𝑖) = (2 · (𝑧 / 2))) | |
4 | 3 | eqeq2d 2751 | . . . . . . 7 ⊢ (𝑖 = (𝑧 / 2) → (𝑧 = (2 · 𝑖) ↔ 𝑧 = (2 · (𝑧 / 2)))) |
5 | 4 | adantl 482 | . . . . . 6 ⊢ (((𝑧 ∈ ℤ ∧ (𝑧 / 2) ∈ ℤ) ∧ 𝑖 = (𝑧 / 2)) → (𝑧 = (2 · 𝑖) ↔ 𝑧 = (2 · (𝑧 / 2)))) |
6 | zcn 12324 | . . . . . . . . 9 ⊢ (𝑧 ∈ ℤ → 𝑧 ∈ ℂ) | |
7 | 6 | adantr 481 | . . . . . . . 8 ⊢ ((𝑧 ∈ ℤ ∧ (𝑧 / 2) ∈ ℤ) → 𝑧 ∈ ℂ) |
8 | 2cnd 12051 | . . . . . . . 8 ⊢ ((𝑧 ∈ ℤ ∧ (𝑧 / 2) ∈ ℤ) → 2 ∈ ℂ) | |
9 | 2ne0 12077 | . . . . . . . . 9 ⊢ 2 ≠ 0 | |
10 | 9 | a1i 11 | . . . . . . . 8 ⊢ ((𝑧 ∈ ℤ ∧ (𝑧 / 2) ∈ ℤ) → 2 ≠ 0) |
11 | 7, 8, 10 | divcan2d 11753 | . . . . . . 7 ⊢ ((𝑧 ∈ ℤ ∧ (𝑧 / 2) ∈ ℤ) → (2 · (𝑧 / 2)) = 𝑧) |
12 | 11 | eqcomd 2746 | . . . . . 6 ⊢ ((𝑧 ∈ ℤ ∧ (𝑧 / 2) ∈ ℤ) → 𝑧 = (2 · (𝑧 / 2))) |
13 | 2, 5, 12 | rspcedvd 3564 | . . . . 5 ⊢ ((𝑧 ∈ ℤ ∧ (𝑧 / 2) ∈ ℤ) → ∃𝑖 ∈ ℤ 𝑧 = (2 · 𝑖)) |
14 | 13 | ex 413 | . . . 4 ⊢ (𝑧 ∈ ℤ → ((𝑧 / 2) ∈ ℤ → ∃𝑖 ∈ ℤ 𝑧 = (2 · 𝑖))) |
15 | oveq1 7278 | . . . . . . 7 ⊢ (𝑧 = (2 · 𝑖) → (𝑧 / 2) = ((2 · 𝑖) / 2)) | |
16 | zcn 12324 | . . . . . . . . 9 ⊢ (𝑖 ∈ ℤ → 𝑖 ∈ ℂ) | |
17 | 16 | adantl 482 | . . . . . . . 8 ⊢ ((𝑧 ∈ ℤ ∧ 𝑖 ∈ ℤ) → 𝑖 ∈ ℂ) |
18 | 2cnd 12051 | . . . . . . . 8 ⊢ ((𝑧 ∈ ℤ ∧ 𝑖 ∈ ℤ) → 2 ∈ ℂ) | |
19 | 9 | a1i 11 | . . . . . . . 8 ⊢ ((𝑧 ∈ ℤ ∧ 𝑖 ∈ ℤ) → 2 ≠ 0) |
20 | 17, 18, 19 | divcan3d 11756 | . . . . . . 7 ⊢ ((𝑧 ∈ ℤ ∧ 𝑖 ∈ ℤ) → ((2 · 𝑖) / 2) = 𝑖) |
21 | 15, 20 | sylan9eqr 2802 | . . . . . 6 ⊢ (((𝑧 ∈ ℤ ∧ 𝑖 ∈ ℤ) ∧ 𝑧 = (2 · 𝑖)) → (𝑧 / 2) = 𝑖) |
22 | simpr 485 | . . . . . . 7 ⊢ ((𝑧 ∈ ℤ ∧ 𝑖 ∈ ℤ) → 𝑖 ∈ ℤ) | |
23 | 22 | adantr 481 | . . . . . 6 ⊢ (((𝑧 ∈ ℤ ∧ 𝑖 ∈ ℤ) ∧ 𝑧 = (2 · 𝑖)) → 𝑖 ∈ ℤ) |
24 | 21, 23 | eqeltrd 2841 | . . . . 5 ⊢ (((𝑧 ∈ ℤ ∧ 𝑖 ∈ ℤ) ∧ 𝑧 = (2 · 𝑖)) → (𝑧 / 2) ∈ ℤ) |
25 | 24 | rexlimdva2 3218 | . . . 4 ⊢ (𝑧 ∈ ℤ → (∃𝑖 ∈ ℤ 𝑧 = (2 · 𝑖) → (𝑧 / 2) ∈ ℤ)) |
26 | 14, 25 | impbid 211 | . . 3 ⊢ (𝑧 ∈ ℤ → ((𝑧 / 2) ∈ ℤ ↔ ∃𝑖 ∈ ℤ 𝑧 = (2 · 𝑖))) |
27 | 26 | rabbiia 3405 | . 2 ⊢ {𝑧 ∈ ℤ ∣ (𝑧 / 2) ∈ ℤ} = {𝑧 ∈ ℤ ∣ ∃𝑖 ∈ ℤ 𝑧 = (2 · 𝑖)} |
28 | 1, 27 | eqtri 2768 | 1 ⊢ Even = {𝑧 ∈ ℤ ∣ ∃𝑖 ∈ ℤ 𝑧 = (2 · 𝑖)} |
Colors of variables: wff setvar class |
Syntax hints: ↔ wb 205 ∧ wa 396 = wceq 1542 ∈ wcel 2110 ≠ wne 2945 ∃wrex 3067 {crab 3070 (class class class)co 7271 ℂcc 10870 0cc0 10872 · cmul 10877 / cdiv 11632 2c2 12028 ℤcz 12319 Even ceven 45045 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1802 ax-4 1816 ax-5 1917 ax-6 1975 ax-7 2015 ax-8 2112 ax-9 2120 ax-10 2141 ax-11 2158 ax-12 2175 ax-ext 2711 ax-sep 5227 ax-nul 5234 ax-pow 5292 ax-pr 5356 ax-un 7582 ax-resscn 10929 ax-1cn 10930 ax-icn 10931 ax-addcl 10932 ax-addrcl 10933 ax-mulcl 10934 ax-mulrcl 10935 ax-mulcom 10936 ax-addass 10937 ax-mulass 10938 ax-distr 10939 ax-i2m1 10940 ax-1ne0 10941 ax-1rid 10942 ax-rnegex 10943 ax-rrecex 10944 ax-cnre 10945 ax-pre-lttri 10946 ax-pre-lttrn 10947 ax-pre-ltadd 10948 ax-pre-mulgt0 10949 |
This theorem depends on definitions: df-bi 206 df-an 397 df-or 845 df-3or 1087 df-3an 1088 df-tru 1545 df-fal 1555 df-ex 1787 df-nf 1791 df-sb 2072 df-mo 2542 df-eu 2571 df-clab 2718 df-cleq 2732 df-clel 2818 df-nfc 2891 df-ne 2946 df-nel 3052 df-ral 3071 df-rex 3072 df-reu 3073 df-rmo 3074 df-rab 3075 df-v 3433 df-sbc 3721 df-csb 3838 df-dif 3895 df-un 3897 df-in 3899 df-ss 3909 df-nul 4263 df-if 4466 df-pw 4541 df-sn 4568 df-pr 4570 df-op 4574 df-uni 4846 df-br 5080 df-opab 5142 df-mpt 5163 df-id 5490 df-po 5504 df-so 5505 df-xp 5596 df-rel 5597 df-cnv 5598 df-co 5599 df-dm 5600 df-rn 5601 df-res 5602 df-ima 5603 df-iota 6390 df-fun 6434 df-fn 6435 df-f 6436 df-f1 6437 df-fo 6438 df-f1o 6439 df-fv 6440 df-riota 7228 df-ov 7274 df-oprab 7275 df-mpo 7276 df-er 8481 df-en 8717 df-dom 8718 df-sdom 8719 df-pnf 11012 df-mnf 11013 df-xr 11014 df-ltxr 11015 df-le 11016 df-sub 11207 df-neg 11208 df-div 11633 df-2 12036 df-z 12320 df-even 45047 |
This theorem is referenced by: m1expevenALTV 45068 dfeven2 45070 opoeALTV 45104 opeoALTV 45105 |
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