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| Description: The value of the Möbius function. (Contributed by Mario Carneiro, 22-Sep-2014.) | 
| Ref | Expression | 
|---|---|
| muval | ⊢ (𝐴 ∈ ℕ → (μ‘𝐴) = if(∃𝑝 ∈ ℙ (𝑝↑2) ∥ 𝐴, 0, (-1↑(♯‘{𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝐴})))) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | breq2 5146 | . . . 4 ⊢ (𝑥 = 𝐴 → ((𝑝↑2) ∥ 𝑥 ↔ (𝑝↑2) ∥ 𝐴)) | |
| 2 | 1 | rexbidv 3178 | . . 3 ⊢ (𝑥 = 𝐴 → (∃𝑝 ∈ ℙ (𝑝↑2) ∥ 𝑥 ↔ ∃𝑝 ∈ ℙ (𝑝↑2) ∥ 𝐴)) | 
| 3 | breq2 5146 | . . . . . 6 ⊢ (𝑥 = 𝐴 → (𝑝 ∥ 𝑥 ↔ 𝑝 ∥ 𝐴)) | |
| 4 | 3 | rabbidv 3443 | . . . . 5 ⊢ (𝑥 = 𝐴 → {𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝑥} = {𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝐴}) | 
| 5 | 4 | fveq2d 6909 | . . . 4 ⊢ (𝑥 = 𝐴 → (♯‘{𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝑥}) = (♯‘{𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝐴})) | 
| 6 | 5 | oveq2d 7448 | . . 3 ⊢ (𝑥 = 𝐴 → (-1↑(♯‘{𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝑥})) = (-1↑(♯‘{𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝐴}))) | 
| 7 | 2, 6 | ifbieq2d 4551 | . 2 ⊢ (𝑥 = 𝐴 → if(∃𝑝 ∈ ℙ (𝑝↑2) ∥ 𝑥, 0, (-1↑(♯‘{𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝑥}))) = if(∃𝑝 ∈ ℙ (𝑝↑2) ∥ 𝐴, 0, (-1↑(♯‘{𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝐴})))) | 
| 8 | df-mu 27145 | . 2 ⊢ μ = (𝑥 ∈ ℕ ↦ if(∃𝑝 ∈ ℙ (𝑝↑2) ∥ 𝑥, 0, (-1↑(♯‘{𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝑥})))) | |
| 9 | c0ex 11256 | . . 3 ⊢ 0 ∈ V | |
| 10 | ovex 7465 | . . 3 ⊢ (-1↑(♯‘{𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝐴})) ∈ V | |
| 11 | 9, 10 | ifex 4575 | . 2 ⊢ if(∃𝑝 ∈ ℙ (𝑝↑2) ∥ 𝐴, 0, (-1↑(♯‘{𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝐴}))) ∈ V | 
| 12 | 7, 8, 11 | fvmpt 7015 | 1 ⊢ (𝐴 ∈ ℕ → (μ‘𝐴) = if(∃𝑝 ∈ ℙ (𝑝↑2) ∥ 𝐴, 0, (-1↑(♯‘{𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝐴})))) | 
| Colors of variables: wff setvar class | 
| Syntax hints: → wi 4 = wceq 1539 ∈ wcel 2107 ∃wrex 3069 {crab 3435 ifcif 4524 class class class wbr 5142 ‘cfv 6560 (class class class)co 7432 0cc0 11156 1c1 11157 -cneg 11494 ℕcn 12267 2c2 12322 ↑cexp 14103 ♯chash 14370 ∥ cdvds 16291 ℙcprime 16709 μcmu 27139 | 
| This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1794 ax-4 1808 ax-5 1909 ax-6 1966 ax-7 2006 ax-8 2109 ax-9 2117 ax-10 2140 ax-11 2156 ax-12 2176 ax-ext 2707 ax-sep 5295 ax-nul 5305 ax-pr 5431 ax-1cn 11214 ax-icn 11215 ax-addcl 11216 ax-mulcl 11218 ax-i2m1 11224 | 
| This theorem depends on definitions: df-bi 207 df-an 396 df-or 848 df-3an 1088 df-tru 1542 df-fal 1552 df-ex 1779 df-nf 1783 df-sb 2064 df-mo 2539 df-eu 2568 df-clab 2714 df-cleq 2728 df-clel 2815 df-nfc 2891 df-ne 2940 df-ral 3061 df-rex 3070 df-rab 3436 df-v 3481 df-dif 3953 df-un 3955 df-ss 3967 df-nul 4333 df-if 4525 df-sn 4626 df-pr 4628 df-op 4632 df-uni 4907 df-br 5143 df-opab 5205 df-mpt 5225 df-id 5577 df-xp 5690 df-rel 5691 df-cnv 5692 df-co 5693 df-dm 5694 df-iota 6513 df-fun 6562 df-fv 6568 df-ov 7435 df-mu 27145 | 
| This theorem is referenced by: muval1 27177 muval2 27178 isnsqf 27179 mule1 27192 | 
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