P. 275 of Theorem List - Metamath Proof Explorer

Theorem List for Metamath Proof Explorer - 27401-27500   *Has distinct variable group(s)

Type	Label	Description
Statement
Theorem	lgamcl 27401	The log-Gamma function is a complex function defined on the whole complex plane except for the negative integers. (Contributed by Mario Carneiro, 8-Jul-2017.)
⊢ (𝐴 ∈ (ℂ ∖ (ℤ ∖ ℕ)) → (log Γ‘𝐴) ∈ ℂ)
Theorem	lgamf 27402	The log-Gamma function is a complex function defined on the whole complex plane except for the negative integers. (Contributed by Mario Carneiro, 6-Jul-2017.)
⊢ log Γ:(ℂ ∖ (ℤ ∖ ℕ))⟶ℂ
Theorem	gamf 27403	The Gamma function is a complex function defined on the whole complex plane except for the negative integers. (Contributed by Mario Carneiro, 6-Jul-2017.)
⊢ Γ:(ℂ ∖ (ℤ ∖ ℕ))⟶ℂ
Theorem	gamcl 27404	The exponential of the log-Gamma function is the Gamma function (by definition). (Contributed by Mario Carneiro, 8-Jul-2017.)
⊢ (𝐴 ∈ (ℂ ∖ (ℤ ∖ ℕ)) → (Γ‘𝐴) ∈ ℂ)
Theorem	eflgam 27405	The exponential of the log-Gamma function is the Gamma function (by definition). (Contributed by Mario Carneiro, 8-Jul-2017.)
⊢ (𝐴 ∈ (ℂ ∖ (ℤ ∖ ℕ)) → (exp‘(log Γ‘𝐴)) = (Γ‘𝐴))
Theorem	gamne0 27406	The Gamma function is never zero. (Contributed by Mario Carneiro, 9-Jul-2017.)
⊢ (𝐴 ∈ (ℂ ∖ (ℤ ∖ ℕ)) → (Γ‘𝐴) ≠ 0)
Theorem	igamval 27407	Value of the inverse Gamma function. (Contributed by Mario Carneiro, 16-Jul-2017.)
⊢ (𝐴 ∈ ℂ → (1/Γ‘𝐴) = if(𝐴 ∈ (ℤ ∖ ℕ), 0, (1 / (Γ‘𝐴))))
Theorem	igamz 27408	Value of the inverse Gamma function on nonpositive integers. (Contributed by Mario Carneiro, 16-Jul-2017.)
⊢ (𝐴 ∈ (ℤ ∖ ℕ) → (1/Γ‘𝐴) = 0)
Theorem	igamgam 27409	Value of the inverse Gamma function in terms of the Gamma function. (Contributed by Mario Carneiro, 16-Jul-2017.)
⊢ (𝐴 ∈ (ℂ ∖ (ℤ ∖ ℕ)) → (1/Γ‘𝐴) = (1 / (Γ‘𝐴)))
Theorem	igamlgam 27410	Value of the inverse Gamma function in terms of the log-Gamma function. (Contributed by Mario Carneiro, 16-Jul-2017.)
⊢ (𝐴 ∈ (ℂ ∖ (ℤ ∖ ℕ)) → (1/Γ‘𝐴) = (exp‘ -(log Γ‘𝐴)))
Theorem	igamf 27411	Closure of the inverse Gamma function. (Contributed by Mario Carneiro, 16-Jul-2017.)
⊢ 1/Γ:ℂ⟶ℂ
Theorem	igamcl 27412	Closure of the inverse Gamma function. (Contributed by Mario Carneiro, 16-Jul-2017.)
⊢ (𝐴 ∈ ℂ → (1/Γ‘𝐴) ∈ ℂ)
Theorem	gamigam 27413	The Gamma function is the inverse of the inverse Gamma function. (Contributed by Mario Carneiro, 16-Jul-2017.)
⊢ (𝐴 ∈ (ℂ ∖ (ℤ ∖ ℕ)) → (Γ‘𝐴) = (1 / (1/Γ‘𝐴)))
Theorem	lgamcvg 27414*	The series 𝐺 converges to log Γ(𝐴) + log(𝐴). (Contributed by Mario Carneiro, 6-Jul-2017.)
⊢ 𝐺 = (𝑚 ∈ ℕ ↦ ((𝐴 · (log‘((𝑚 + 1) / 𝑚))) − (log‘((𝐴 / 𝑚) + 1))))    &   ⊢ (𝜑 → 𝐴 ∈ (ℂ ∖ (ℤ ∖ ℕ)))    ⇒   ⊢ (𝜑 → seq1( + , 𝐺) ⇝ ((log Γ‘𝐴) + (log‘𝐴)))
Theorem	lgamcvg2 27415*	The series 𝐺 converges to log Γ(𝐴 + 1). (Contributed by Mario Carneiro, 9-Jul-2017.)
⊢ 𝐺 = (𝑚 ∈ ℕ ↦ ((𝐴 · (log‘((𝑚 + 1) / 𝑚))) − (log‘((𝐴 / 𝑚) + 1))))    &   ⊢ (𝜑 → 𝐴 ∈ (ℂ ∖ (ℤ ∖ ℕ)))    ⇒   ⊢ (𝜑 → seq1( + , 𝐺) ⇝ (log Γ‘(𝐴 + 1)))
Theorem	gamcvg 27416*	The pointwise exponential of the series 𝐺 converges to Γ(𝐴) · 𝐴. (Contributed by Mario Carneiro, 6-Jul-2017.)
⊢ 𝐺 = (𝑚 ∈ ℕ ↦ ((𝐴 · (log‘((𝑚 + 1) / 𝑚))) − (log‘((𝐴 / 𝑚) + 1))))    &   ⊢ (𝜑 → 𝐴 ∈ (ℂ ∖ (ℤ ∖ ℕ)))    ⇒   ⊢ (𝜑 → (exp ∘ seq1( + , 𝐺)) ⇝ ((Γ‘𝐴) · 𝐴))
Theorem	lgamp1 27417	The functional equation of the (log) Gamma function. (Contributed by Mario Carneiro, 9-Jul-2017.)
⊢ (𝐴 ∈ (ℂ ∖ (ℤ ∖ ℕ)) → (log Γ‘(𝐴 + 1)) = ((log Γ‘𝐴) + (log‘𝐴)))
Theorem	gamp1 27418	The functional equation of the Gamma function. (Contributed by Mario Carneiro, 9-Jul-2017.)
⊢ (𝐴 ∈ (ℂ ∖ (ℤ ∖ ℕ)) → (Γ‘(𝐴 + 1)) = ((Γ‘𝐴) · 𝐴))
Theorem	gamcvg2lem 27419*	Lemma for gamcvg2 27420. (Contributed by Mario Carneiro, 10-Jul-2017.)
⊢ 𝐹 = (𝑚 ∈ ℕ ↦ ((((𝑚 + 1) / 𝑚)↑𝑐𝐴) / ((𝐴 / 𝑚) + 1)))    &   ⊢ (𝜑 → 𝐴 ∈ (ℂ ∖ (ℤ ∖ ℕ)))    &   ⊢ 𝐺 = (𝑚 ∈ ℕ ↦ ((𝐴 · (log‘((𝑚 + 1) / 𝑚))) − (log‘((𝐴 / 𝑚) + 1))))    ⇒   ⊢ (𝜑 → (exp ∘ seq1( + , 𝐺)) = seq1( · , 𝐹))
Theorem	gamcvg2 27420*	An infinite product expression for the gamma function. (Contributed by Mario Carneiro, 9-Jul-2017.)
⊢ 𝐹 = (𝑚 ∈ ℕ ↦ ((((𝑚 + 1) / 𝑚)↑𝑐𝐴) / ((𝐴 / 𝑚) + 1)))    &   ⊢ (𝜑 → 𝐴 ∈ (ℂ ∖ (ℤ ∖ ℕ)))    ⇒   ⊢ (𝜑 → seq1( · , 𝐹) ⇝ ((Γ‘𝐴) · 𝐴))
Theorem	regamcl 27421	The Gamma function is real for real input. (Contributed by Mario Carneiro, 9-Jul-2017.)
⊢ (𝐴 ∈ (ℝ ∖ (ℤ ∖ ℕ)) → (Γ‘𝐴) ∈ ℝ)
Theorem	relgamcl 27422	The log-Gamma function is real for positive real input. (Contributed by Mario Carneiro, 9-Jul-2017.)
⊢ (𝐴 ∈ ℝ+ → (log Γ‘𝐴) ∈ ℝ)
Theorem	rpgamcl 27423	The log-Gamma function is positive real for positive real input. (Contributed by Mario Carneiro, 9-Jul-2017.)
⊢ (𝐴 ∈ ℝ+ → (Γ‘𝐴) ∈ ℝ+)
Theorem	lgam1 27424	The log-Gamma function at one. (Contributed by Mario Carneiro, 9-Jul-2017.)
⊢ (log Γ‘1) = 0
Theorem	gam1 27425	The log-Gamma function at one. (Contributed by Mario Carneiro, 9-Jul-2017.)
⊢ (Γ‘1) = 1
Theorem	facgam 27426	The Gamma function generalizes the factorial. (Contributed by Mario Carneiro, 9-Jul-2017.)
⊢ (𝑁 ∈ ℕ0 → (!‘𝑁) = (Γ‘(𝑁 + 1)))
Theorem	gamfac 27427	The Gamma function generalizes the factorial. (Contributed by Mario Carneiro, 9-Jul-2017.)
⊢ (𝑁 ∈ ℕ → (Γ‘𝑁) = (!‘(𝑁 − 1)))
14.4  Basic number theory
14.4.1  Wilson's theorem
Theorem	wilthlem1 27428	The only elements that are equal to their own inverses in the multiplicative group of nonzero elements in ℤ / 𝑃ℤ are 1 and -1≡𝑃 − 1. (Note that from prmdiveq 16995, (𝑁↑(𝑃 − 2)) mod 𝑃 is the modular inverse of 𝑁 in ℤ / 𝑃ℤ. (Contributed by Mario Carneiro, 24-Jan-2015.)
⊢ ((𝑃 ∈ ℙ ∧ 𝑁 ∈ (1...(𝑃 − 1))) → (𝑁 = ((𝑁↑(𝑃 − 2)) mod 𝑃) ↔ (𝑁 = 1 ∨ 𝑁 = (𝑃 − 1))))
Theorem	wilthlem2 27429*	Lemma for wilth 27431: induction step. The "hand proof" version of this theorem works by writing out the list of all numbers from 1 to 𝑃 − 1 in pairs such that a number is paired with its inverse. Every number has a unique inverse different from itself except 1 and 𝑃 − 1, and so each pair multiplies to 1, and 1 and 𝑃 − 1≡ -1 multiply to -1, so the full product is equal to -1. Here we make this precise by doing the product pair by pair. The induction hypothesis says that every subset 𝑆 of 1...(𝑃 − 1) that is closed under inverse (i.e. all pairs are matched up) and contains 𝑃 − 1 multiplies to -1 mod 𝑃. Given such a set, we take out one element 𝑧 ≠ 𝑃 − 1. If there are no such elements, then 𝑆 = {𝑃 − 1} which forms the base case. Otherwise, 𝑆 ∖ {𝑧, 𝑧↑ -1} is also closed under inverse and contains 𝑃 − 1, so the induction hypothesis says that this equals -1; and the remaining two elements are either equal to each other, in which case wilthlem1 27428 gives that 𝑧 = 1 or 𝑃 − 1, and we've already excluded the second case, so the product gives 1; or 𝑧 ≠ 𝑧↑ -1 and their product is 1. In either case the accumulated product is unaffected. (Contributed by Mario Carneiro, 24-Jan-2015.) (Proof shortened by AV, 27-Jul-2019.)
⊢ 𝑇 = (mulGrp‘ℂfld)    &   ⊢ 𝐴 = {𝑥 ∈ 𝒫 (1...(𝑃 − 1)) ∣ ((𝑃 − 1) ∈ 𝑥 ∧ ∀𝑦 ∈ 𝑥 ((𝑦↑(𝑃 − 2)) mod 𝑃) ∈ 𝑥)}    &   ⊢ (𝜑 → 𝑃 ∈ ℙ)    &   ⊢ (𝜑 → 𝑆 ∈ 𝐴)    &   ⊢ (𝜑 → ∀𝑠 ∈ 𝐴 (𝑠 ⊊ 𝑆 → ((𝑇 Σg ( I ↾ 𝑠)) mod 𝑃) = ( -1 mod 𝑃)))    ⇒   ⊢ (𝜑 → ((𝑇 Σg ( I ↾ 𝑆)) mod 𝑃) = ( -1 mod 𝑃))
Theorem	wilthlem3 27430*	Lemma for wilth 27431. Here we round out the argument of wilthlem2 27429 with the final step of the induction. The induction argument shows that every subset of 1...(𝑃 − 1) that is closed under inverse and contains 𝑃 − 1 multiplies to -1 mod 𝑃, and clearly 1...(𝑃 − 1) itself is such a set. Thus, the product of all the elements is -1, and all that is left is to translate the group sum notation (which we used for its unordered summing capabilities) into an ordered sequence to match the definition of the factorial. (Contributed by Mario Carneiro, 24-Jan-2015.) (Proof shortened by AV, 27-Jul-2019.)
⊢ 𝑇 = (mulGrp‘ℂfld)    &   ⊢ 𝐴 = {𝑥 ∈ 𝒫 (1...(𝑃 − 1)) ∣ ((𝑃 − 1) ∈ 𝑥 ∧ ∀𝑦 ∈ 𝑥 ((𝑦↑(𝑃 − 2)) mod 𝑃) ∈ 𝑥)}    ⇒   ⊢ (𝑃 ∈ ℙ → 𝑃 ∥ ((!‘(𝑃 − 1)) + 1))
Theorem	wilth 27431	Wilson's theorem. A number is prime iff it is greater than or equal to 2 and (𝑁 − 1)! is congruent to -1, mod 𝑁, or alternatively if 𝑁 divides (𝑁 − 1)! + 1. In this part of the proof we show the relatively simple reverse implication; see wilthlem3 27430 for the forward implication. This is Metamath 100 proof #51. (Contributed by Mario Carneiro, 24-Jan-2015.) (Proof shortened by Fan Zheng, 16-Jun-2016.)
⊢ (𝑁 ∈ ℙ ↔ (𝑁 ∈ (ℤ≥‘2) ∧ 𝑁 ∥ ((!‘(𝑁 − 1)) + 1)))
Theorem	wilthimp 27432	The forward implication of Wilson's theorem wilth 27431 (see wilthlem3 27430), expressed using the modulo operation: For any prime 𝑝 we have (𝑝 − 1)!≡ − 1 (mod 𝑝), see theorem 5.24 in [ApostolNT] p. 116. (Contributed by AV, 21-Jul-2021.)
⊢ (𝑃 ∈ ℙ → ((!‘(𝑃 − 1)) mod 𝑃) = ( -1 mod 𝑃))
14.4.2  The Fundamental Theorem of Algebra
Theorem	ftalem1 27433*	Lemma for fta 27440: "growth lemma". There exists some 𝑟 such that 𝐹 is arbitrarily close in proportion to its dominant term. (Contributed by Mario Carneiro, 14-Sep-2014.)
⊢ 𝐴 = (coeff‘𝐹)    &   ⊢ 𝑁 = (deg‘𝐹)    &   ⊢ (𝜑 → 𝐹 ∈ (Poly‘𝑆))    &   ⊢ (𝜑 → 𝑁 ∈ ℕ)    &   ⊢ (𝜑 → 𝐸 ∈ ℝ+)    &   ⊢ 𝑇 = (Σ𝑘 ∈ (0...(𝑁 − 1))(abs‘(𝐴‘𝑘)) / 𝐸)    ⇒   ⊢ (𝜑 → ∃𝑟 ∈ ℝ ∀𝑥 ∈ ℂ (𝑟 < (abs‘𝑥) → (abs‘((𝐹‘𝑥) − ((𝐴‘𝑁) · (𝑥↑𝑁)))) < (𝐸 · ((abs‘𝑥)↑𝑁))))
Theorem	ftalem2 27434*	Lemma for fta 27440. There exists some 𝑟 such that 𝐹 has magnitude greater than 𝐹(0) outside the closed ball B(0,r). (Contributed by Mario Carneiro, 14-Sep-2014.)
⊢ 𝐴 = (coeff‘𝐹)    &   ⊢ 𝑁 = (deg‘𝐹)    &   ⊢ (𝜑 → 𝐹 ∈ (Poly‘𝑆))    &   ⊢ (𝜑 → 𝑁 ∈ ℕ)    &   ⊢ 𝑈 = if(if(1 ≤ 𝑠, 𝑠, 1) ≤ 𝑇, 𝑇, if(1 ≤ 𝑠, 𝑠, 1))    &   ⊢ 𝑇 = ((abs‘(𝐹‘0)) / ((abs‘(𝐴‘𝑁)) / 2))    ⇒   ⊢ (𝜑 → ∃𝑟 ∈ ℝ+ ∀𝑥 ∈ ℂ (𝑟 < (abs‘𝑥) → (abs‘(𝐹‘0)) < (abs‘(𝐹‘𝑥))))
Theorem	ftalem3 27435*	Lemma for fta 27440. There exists a global minimum of the function abs ∘ 𝐹. The proof uses a circle of radius 𝑟 where 𝑟 is the value coming from ftalem1 27433; since this is a compact set, the minimum on this disk is achieved, and this must then be the global minimum. (Contributed by Mario Carneiro, 14-Sep-2014.)
⊢ 𝐴 = (coeff‘𝐹)    &   ⊢ 𝑁 = (deg‘𝐹)    &   ⊢ (𝜑 → 𝐹 ∈ (Poly‘𝑆))    &   ⊢ (𝜑 → 𝑁 ∈ ℕ)    &   ⊢ 𝐷 = {𝑦 ∈ ℂ ∣ (abs‘𝑦) ≤ 𝑅}    &   ⊢ 𝐽 = (TopOpen‘ℂfld)    &   ⊢ (𝜑 → 𝑅 ∈ ℝ+)    &   ⊢ (𝜑 → ∀𝑥 ∈ ℂ (𝑅 < (abs‘𝑥) → (abs‘(𝐹‘0)) < (abs‘(𝐹‘𝑥))))    ⇒   ⊢ (𝜑 → ∃𝑧 ∈ ℂ ∀𝑥 ∈ ℂ (abs‘(𝐹‘𝑧)) ≤ (abs‘(𝐹‘𝑥)))
Theorem	ftalem4 27436*	Lemma for fta 27440: Closure of the auxiliary variables for ftalem5 27437. (Contributed by Mario Carneiro, 20-Sep-2014.) (Revised by AV, 28-Sep-2020.)
⊢ 𝐴 = (coeff‘𝐹)    &   ⊢ 𝑁 = (deg‘𝐹)    &   ⊢ (𝜑 → 𝐹 ∈ (Poly‘𝑆))    &   ⊢ (𝜑 → 𝑁 ∈ ℕ)    &   ⊢ (𝜑 → (𝐹‘0) ≠ 0)    &   ⊢ 𝐾 = inf({𝑛 ∈ ℕ ∣ (𝐴‘𝑛) ≠ 0}, ℝ, < )    &   ⊢ 𝑇 = ( -((𝐹‘0) / (𝐴‘𝐾))↑𝑐(1 / 𝐾))    &   ⊢ 𝑈 = ((abs‘(𝐹‘0)) / (Σ𝑘 ∈ ((𝐾 + 1)...𝑁)(abs‘((𝐴‘𝑘) · (𝑇↑𝑘))) + 1))    &   ⊢ 𝑋 = if(1 ≤ 𝑈, 1, 𝑈)    ⇒   ⊢ (𝜑 → ((𝐾 ∈ ℕ ∧ (𝐴‘𝐾) ≠ 0) ∧ (𝑇 ∈ ℂ ∧ 𝑈 ∈ ℝ+ ∧ 𝑋 ∈ ℝ+)))
Theorem	ftalem5 27437*	Lemma for fta 27440: Main proof. We have already shifted the minimum found in ftalem3 27435 to zero by a change of variables, and now we show that the minimum value is zero. Expanding in a series about the minimum value, let 𝐾 be the lowest term in the polynomial that is nonzero, and let 𝑇 be a 𝐾-th root of -𝐹(0) / 𝐴(𝐾). Then an evaluation of 𝐹(𝑇𝑋) where 𝑋 is a sufficiently small positive number yields 𝐹(0) for the first term and -𝐹(0) · 𝑋↑𝐾 for the 𝐾-th term, and all higher terms are bounded because 𝑋 is small. Thus, abs(𝐹(𝑇𝑋)) ≤ abs(𝐹(0))(1 − 𝑋↑𝐾) < abs(𝐹(0)), in contradiction to our choice of 𝐹(0) as the minimum. (Contributed by Mario Carneiro, 14-Sep-2014.) (Revised by AV, 28-Sep-2020.)
⊢ 𝐴 = (coeff‘𝐹)    &   ⊢ 𝑁 = (deg‘𝐹)    &   ⊢ (𝜑 → 𝐹 ∈ (Poly‘𝑆))    &   ⊢ (𝜑 → 𝑁 ∈ ℕ)    &   ⊢ (𝜑 → (𝐹‘0) ≠ 0)    &   ⊢ 𝐾 = inf({𝑛 ∈ ℕ ∣ (𝐴‘𝑛) ≠ 0}, ℝ, < )    &   ⊢ 𝑇 = ( -((𝐹‘0) / (𝐴‘𝐾))↑𝑐(1 / 𝐾))    &   ⊢ 𝑈 = ((abs‘(𝐹‘0)) / (Σ𝑘 ∈ ((𝐾 + 1)...𝑁)(abs‘((𝐴‘𝑘) · (𝑇↑𝑘))) + 1))    &   ⊢ 𝑋 = if(1 ≤ 𝑈, 1, 𝑈)    ⇒   ⊢ (𝜑 → ∃𝑥 ∈ ℂ (abs‘(𝐹‘𝑥)) < (abs‘(𝐹‘0)))
Theorem	ftalem6 27438*	Lemma for fta 27440: Discharge the auxiliary variables in ftalem5 27437. (Contributed by Mario Carneiro, 20-Sep-2014.) (Proof shortened by AV, 28-Sep-2020.)
⊢ 𝐴 = (coeff‘𝐹)    &   ⊢ 𝑁 = (deg‘𝐹)    &   ⊢ (𝜑 → 𝐹 ∈ (Poly‘𝑆))    &   ⊢ (𝜑 → 𝑁 ∈ ℕ)    &   ⊢ (𝜑 → (𝐹‘0) ≠ 0)    ⇒   ⊢ (𝜑 → ∃𝑥 ∈ ℂ (abs‘(𝐹‘𝑥)) < (abs‘(𝐹‘0)))
Theorem	ftalem7 27439*	Lemma for fta 27440. Shift the minimum away from zero by a change of variables. (Contributed by Mario Carneiro, 14-Sep-2014.)
⊢ 𝐴 = (coeff‘𝐹)    &   ⊢ 𝑁 = (deg‘𝐹)    &   ⊢ (𝜑 → 𝐹 ∈ (Poly‘𝑆))    &   ⊢ (𝜑 → 𝑁 ∈ ℕ)    &   ⊢ (𝜑 → 𝑋 ∈ ℂ)    &   ⊢ (𝜑 → (𝐹‘𝑋) ≠ 0)    ⇒   ⊢ (𝜑 → ¬ ∀𝑥 ∈ ℂ (abs‘(𝐹‘𝑋)) ≤ (abs‘(𝐹‘𝑥)))
Theorem	fta 27440*	The Fundamental Theorem of Algebra. Any polynomial with positive degree (i.e. non-constant) has a root. This is Metamath 100 proof #2. (Contributed by Mario Carneiro, 15-Sep-2014.)
⊢ ((𝐹 ∈ (Poly‘𝑆) ∧ (deg‘𝐹) ∈ ℕ) → ∃𝑧 ∈ ℂ (𝐹‘𝑧) = 0)
14.4.3  The Basel problem (ζ(2) = π2/6)
Theorem	basellem1 27441	Lemma for basel 27450. Closure of the sequence of roots. (Contributed by Mario Carneiro, 30-Jul-2014.) Replace OLD theorem. (Revised by Wolf Lammen, 18-Sep-2020.)
⊢ 𝑁 = ((2 · 𝑀) + 1)    ⇒   ⊢ ((𝑀 ∈ ℕ ∧ 𝐾 ∈ (1...𝑀)) → ((𝐾 · π) / 𝑁) ∈ (0(,)(π / 2)))
Theorem	basellem2 27442*	Lemma for basel 27450. Show that 𝑃 is a polynomial of degree 𝑀, and compute its coefficient function. (Contributed by Mario Carneiro, 30-Jul-2014.)
⊢ 𝑁 = ((2 · 𝑀) + 1)    &   ⊢ 𝑃 = (𝑡 ∈ ℂ ↦ Σ𝑗 ∈ (0...𝑀)(((𝑁C(2 · 𝑗)) · ( -1↑(𝑀 − 𝑗))) · (𝑡↑𝑗)))    ⇒   ⊢ (𝑀 ∈ ℕ → (𝑃 ∈ (Poly‘ℂ) ∧ (deg‘𝑃) = 𝑀 ∧ (coeff‘𝑃) = (𝑛 ∈ ℕ0 ↦ ((𝑁C(2 · 𝑛)) · ( -1↑(𝑀 − 𝑛))))))
Theorem	basellem3 27443*	Lemma for basel 27450. Using the binomial theorem and de Moivre's formula, we have the identity e↑i𝑁𝑥 / (sin𝑥)↑𝑛 = Σ𝑚 ∈ (0...𝑁)(𝑁C𝑚)(i↑𝑚)(cot𝑥)↑(𝑁 − 𝑚), so taking imaginary parts yields sin(𝑁𝑥) / (sin𝑥)↑𝑁 = Σ𝑗 ∈ (0...𝑀)(𝑁C2𝑗)( -1)↑(𝑀 − 𝑗) (cot𝑥)↑( -2𝑗) = 𝑃((cot𝑥)↑2), where 𝑁 = 2𝑀 + 1. (Contributed by Mario Carneiro, 30-Jul-2014.)
⊢ 𝑁 = ((2 · 𝑀) + 1)    &   ⊢ 𝑃 = (𝑡 ∈ ℂ ↦ Σ𝑗 ∈ (0...𝑀)(((𝑁C(2 · 𝑗)) · ( -1↑(𝑀 − 𝑗))) · (𝑡↑𝑗)))    ⇒   ⊢ ((𝑀 ∈ ℕ ∧ 𝐴 ∈ (0(,)(π / 2))) → (𝑃‘((tan‘𝐴)↑ -2)) = ((sin‘(𝑁 · 𝐴)) / ((sin‘𝐴)↑𝑁)))
Theorem	basellem4 27444*	Lemma for basel 27450. By basellem3 27443, the expression 𝑃((cot𝑥)↑2) = sin(𝑁𝑥) / (sin𝑥)↑𝑁 goes to zero whenever 𝑥 = 𝑛π / 𝑁 for some 𝑛 ∈ (1...𝑀), so this function enumerates 𝑀 distinct roots of a degree- 𝑀 polynomial, which must therefore be all the roots by fta1 26662. (Contributed by Mario Carneiro, 28-Jul-2014.)
⊢ 𝑁 = ((2 · 𝑀) + 1)    &   ⊢ 𝑃 = (𝑡 ∈ ℂ ↦ Σ𝑗 ∈ (0...𝑀)(((𝑁C(2 · 𝑗)) · ( -1↑(𝑀 − 𝑗))) · (𝑡↑𝑗)))    &   ⊢ 𝑇 = (𝑛 ∈ (1...𝑀) ↦ ((tan‘((𝑛 · π) / 𝑁))↑ -2))    ⇒   ⊢ (𝑀 ∈ ℕ → 𝑇:(1...𝑀)⟶1-1onto(◡𝑃 “ {0}))
Theorem	basellem5 27445*	Lemma for basel 27450. Using vieta1 26668, we can calculate the sum of the roots of 𝑃 as the quotient of the top two coefficients, and since the function 𝑇 enumerates the roots, we are left with an equation that sums the cot↑2 function at the 𝑀 different roots. (Contributed by Mario Carneiro, 29-Jul-2014.)
⊢ 𝑁 = ((2 · 𝑀) + 1)    &   ⊢ 𝑃 = (𝑡 ∈ ℂ ↦ Σ𝑗 ∈ (0...𝑀)(((𝑁C(2 · 𝑗)) · ( -1↑(𝑀 − 𝑗))) · (𝑡↑𝑗)))    &   ⊢ 𝑇 = (𝑛 ∈ (1...𝑀) ↦ ((tan‘((𝑛 · π) / 𝑁))↑ -2))    ⇒   ⊢ (𝑀 ∈ ℕ → Σ𝑘 ∈ (1...𝑀)((tan‘((𝑘 · π) / 𝑁))↑ -2) = (((2 · 𝑀) · ((2 · 𝑀) − 1)) / 6))
Theorem	basellem6 27446	Lemma for basel 27450. The function 𝐺 goes to zero because it is bounded by 1 / 𝑛. (Contributed by Mario Carneiro, 28-Jul-2014.)
⊢ 𝐺 = (𝑛 ∈ ℕ ↦ (1 / ((2 · 𝑛) + 1)))    ⇒   ⊢ 𝐺 ⇝ 0
Theorem	basellem7 27447	Lemma for basel 27450. The function 1 + 𝐴 · 𝐺 for any fixed 𝐴 goes to 1. (Contributed by Mario Carneiro, 28-Jul-2014.)
⊢ 𝐺 = (𝑛 ∈ ℕ ↦ (1 / ((2 · 𝑛) + 1)))    &   ⊢ 𝐴 ∈ ℂ    ⇒   ⊢ ((ℕ × {1}) ∘f + ((ℕ × {𝐴}) ∘f · 𝐺)) ⇝ 1
Theorem	basellem8 27448*	Lemma for basel 27450. The function 𝐹 of partial sums of the inverse squares is bounded below by 𝐽 and above by 𝐾, obtained by summing the inequality cot↑2𝑥 ≤ 1 / 𝑥↑2 ≤ csc↑2𝑥 = cot↑2𝑥 + 1 over the 𝑀 roots of the polynomial 𝑃, and applying the identity basellem5 27445. (Contributed by Mario Carneiro, 29-Jul-2014.)
⊢ 𝐺 = (𝑛 ∈ ℕ ↦ (1 / ((2 · 𝑛) + 1)))    &   ⊢ 𝐹 = seq1( + , (𝑛 ∈ ℕ ↦ (𝑛↑ -2)))    &   ⊢ 𝐻 = ((ℕ × {((π↑2) / 6)}) ∘f · ((ℕ × {1}) ∘f − 𝐺))    &   ⊢ 𝐽 = (𝐻 ∘f · ((ℕ × {1}) ∘f + ((ℕ × { -2}) ∘f · 𝐺)))    &   ⊢ 𝐾 = (𝐻 ∘f · ((ℕ × {1}) ∘f + 𝐺))    &   ⊢ 𝑁 = ((2 · 𝑀) + 1)    ⇒   ⊢ (𝑀 ∈ ℕ → ((𝐽‘𝑀) ≤ (𝐹‘𝑀) ∧ (𝐹‘𝑀) ≤ (𝐾‘𝑀)))
Theorem	basellem9 27449*	Lemma for basel 27450. Since by basellem8 27448 𝐹 is bounded by two expressions that tend to π↑2 / 6, 𝐹 must also go to π↑2 / 6 by the squeeze theorem climsqz 15840. But the series 𝐹 is exactly the partial sums of 𝑘↑ -2, so it follows that this is also the value of the infinite sum Σ𝑘 ∈ ℕ(𝑘↑ -2). (Contributed by Mario Carneiro, 28-Jul-2014.)
⊢ 𝐺 = (𝑛 ∈ ℕ ↦ (1 / ((2 · 𝑛) + 1)))    &   ⊢ 𝐹 = seq1( + , (𝑛 ∈ ℕ ↦ (𝑛↑ -2)))    &   ⊢ 𝐻 = ((ℕ × {((π↑2) / 6)}) ∘f · ((ℕ × {1}) ∘f − 𝐺))    &   ⊢ 𝐽 = (𝐻 ∘f · ((ℕ × {1}) ∘f + ((ℕ × { -2}) ∘f · 𝐺)))    &   ⊢ 𝐾 = (𝐻 ∘f · ((ℕ × {1}) ∘f + 𝐺))    ⇒   ⊢ Σ𝑘 ∈ ℕ (𝑘↑ -2) = ((π↑2) / 6)
Theorem	basel 27450	The sum of the inverse squares is π↑2 / 6. This is commonly known as the Basel problem, with the first known proof attributed to Euler. See http://en.wikipedia.org/wiki/Basel_problem. This particular proof approach is due to Cauchy (1821). This is Metamath 100 proof #14. (Contributed by Mario Carneiro, 30-Jul-2014.)
⊢ Σ𝑘 ∈ ℕ (𝑘↑ -2) = ((π↑2) / 6)
14.4.4  Number-theoretical functions
Syntax	ccht 27451	Extend class notation with the first Chebyshev function.
class θ
Syntax	cvma 27452	Extend class notation with the von Mangoldt function.
class Λ
Syntax	cchp 27453	Extend class notation with the second Chebyshev function.
class ψ
Syntax	cppi 27454	Extend class notation with the prime-counting function pi.
class π
Syntax	cmu 27455	Extend class notation with the Möbius function.
class μ
Syntax	csgm 27456	Extend class notation with the divisor function.
class σ
Definition	df-cht 27457*	Define the first Chebyshev function, which adds up the logarithms of all primes less than 𝑥, see definition in [ApostolNT] p. 75. The symbol used to represent this function is sometimes the variant greek letter theta shown here and sometimes the greek letter psi, ψ; however, this notation can also refer to the second Chebyshev function, which adds up the logarithms of prime powers instead, see df-chp 27459. See https://en.wikipedia.org/wiki/Chebyshev_function 27459 for a discussion of the two functions. (Contributed by Mario Carneiro, 15-Sep-2014.)
⊢ θ = (𝑥 ∈ ℝ ↦ Σ𝑝 ∈ ((0[,]𝑥) ∩ ℙ)(log‘𝑝))
Definition	df-vma 27458*	Define the von Mangoldt function, which gives the logarithm of the prime at a prime power, and is zero elsewhere, see definition in [ApostolNT] p. 32. (Contributed by Mario Carneiro, 7-Apr-2016.)
⊢ Λ = (𝑥 ∈ ℕ ↦ ⦋{𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝑥} / 𝑠⦌if((♯‘𝑠) = 1, (log‘∪ 𝑠), 0))
Definition	df-chp 27459*	Define the second Chebyshev function, which adds up the logarithms of the primes corresponding to the prime powers less than 𝑥, see definition in [ApostolNT] p. 75. (Contributed by Mario Carneiro, 7-Apr-2016.)
⊢ ψ = (𝑥 ∈ ℝ ↦ Σ𝑛 ∈ (1...(⌊‘𝑥))(Λ‘𝑛))
Definition	df-ppi 27460	Define the prime π function, which counts the number of primes less than or equal to 𝑥, see definition in [ApostolNT] p. 8. (Contributed by Mario Carneiro, 15-Sep-2014.)
⊢ π = (𝑥 ∈ ℝ ↦ (♯‘((0[,]𝑥) ∩ ℙ)))
Definition	df-mu 27461*	Define the Möbius function, which is zero for non-squarefree numbers and is -1 or 1 for squarefree numbers according as to the number of prime divisors of the number is even or odd, see definition in [ApostolNT] p. 24. (Contributed by Mario Carneiro, 22-Sep-2014.)
⊢ μ = (𝑥 ∈ ℕ ↦ if(∃𝑝 ∈ ℙ (𝑝↑2) ∥ 𝑥, 0, ( -1↑(♯‘{𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝑥}))))
Definition	df-sgm 27462*	Define the sum of positive divisors function (𝑥 σ 𝑛), which is the sum of the xth powers of the positive integer divisors of n, see definition in [ApostolNT] p. 38. For 𝑥 = 0, (𝑥 σ 𝑛) counts the number of divisors of 𝑛, i.e. (0 σ 𝑛) is the divisor function, see remark in [ApostolNT] p. 38. (Contributed by Mario Carneiro, 22-Sep-2014.)
⊢ σ = (𝑥 ∈ ℂ, 𝑛 ∈ ℕ ↦ Σ𝑘 ∈ {𝑝 ∈ ℕ ∣ 𝑝 ∥ 𝑛} (𝑘↑𝑐𝑥))
Theorem	efnnfsumcl 27463*	Finite sum closure in the log-integers. (Contributed by Mario Carneiro, 7-Apr-2016.)
⊢ (𝜑 → 𝐴 ∈ Fin)    &   ⊢ ((𝜑 ∧ 𝑘 ∈ 𝐴) → 𝐵 ∈ ℝ)    &   ⊢ ((𝜑 ∧ 𝑘 ∈ 𝐴) → (exp‘𝐵) ∈ ℕ)    ⇒   ⊢ (𝜑 → (exp‘Σ𝑘 ∈ 𝐴 𝐵) ∈ ℕ)
Theorem	ppisval 27464	The set of primes less than 𝐴 expressed using a finite set of integers. (Contributed by Mario Carneiro, 22-Sep-2014.)
⊢ (𝐴 ∈ ℝ → ((0[,]𝐴) ∩ ℙ) = ((2...(⌊‘𝐴)) ∩ ℙ))
Theorem	ppisval2 27465	The set of primes less than 𝐴 expressed using a finite set of integers. (Contributed by Mario Carneiro, 22-Sep-2014.)
⊢ ((𝐴 ∈ ℝ ∧ 2 ∈ (ℤ≥‘𝑀)) → ((0[,]𝐴) ∩ ℙ) = ((𝑀...(⌊‘𝐴)) ∩ ℙ))
Theorem	ppifi 27466	The set of primes less than 𝐴 is a finite set. (Contributed by Mario Carneiro, 15-Sep-2014.)
⊢ (𝐴 ∈ ℝ → ((0[,]𝐴) ∩ ℙ) ∈ Fin)
Theorem	prmdvdsfi 27467*	The set of prime divisors of a number is a finite set. (Contributed by Mario Carneiro, 7-Apr-2016.)
⊢ (𝐴 ∈ ℕ → {𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝐴} ∈ Fin)
Theorem	chtf 27468	Domain and codoamin of the Chebyshev function. (Contributed by Mario Carneiro, 15-Sep-2014.)
⊢ θ:ℝ⟶ℝ
Theorem	chtcl 27469	Real closure of the Chebyshev function. (Contributed by Mario Carneiro, 15-Sep-2014.)
⊢ (𝐴 ∈ ℝ → (θ‘𝐴) ∈ ℝ)
Theorem	chtval 27470*	Value of the Chebyshev function. (Contributed by Mario Carneiro, 15-Sep-2014.)
⊢ (𝐴 ∈ ℝ → (θ‘𝐴) = Σ𝑝 ∈ ((0[,]𝐴) ∩ ℙ)(log‘𝑝))
Theorem	efchtcl 27471	The Chebyshev function is closed in the log-integers. (Contributed by Mario Carneiro, 22-Sep-2014.) (Revised by Mario Carneiro, 7-Apr-2016.)
⊢ (𝐴 ∈ ℝ → (exp‘(θ‘𝐴)) ∈ ℕ)
Theorem	chtge0 27472	The Chebyshev function is always positive. (Contributed by Mario Carneiro, 15-Sep-2014.)
⊢ (𝐴 ∈ ℝ → 0 ≤ (θ‘𝐴))
Theorem	vmaval 27473*	Value of the von Mangoldt function. (Contributed by Mario Carneiro, 7-Apr-2016.)
⊢ 𝑆 = {𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝐴}    ⇒   ⊢ (𝐴 ∈ ℕ → (Λ‘𝐴) = if((♯‘𝑆) = 1, (log‘∪ 𝑆), 0))
Theorem	isppw 27474*	Two ways to say that 𝐴 is a prime power. (Contributed by Mario Carneiro, 7-Apr-2016.)
⊢ (𝐴 ∈ ℕ → ((Λ‘𝐴) ≠ 0 ↔ ∃!𝑝 ∈ ℙ 𝑝 ∥ 𝐴))
Theorem	isppw2 27475*	Two ways to say that 𝐴 is a prime power. (Contributed by Mario Carneiro, 7-Apr-2016.)
⊢ (𝐴 ∈ ℕ → ((Λ‘𝐴) ≠ 0 ↔ ∃𝑝 ∈ ℙ ∃𝑘 ∈ ℕ 𝐴 = (𝑝↑𝑘)))
Theorem	vmappw 27476	Value of the von Mangoldt function at a prime power. (Contributed by Mario Carneiro, 7-Apr-2016.)
⊢ ((𝑃 ∈ ℙ ∧ 𝐾 ∈ ℕ) → (Λ‘(𝑃↑𝐾)) = (log‘𝑃))
Theorem	vmaprm 27477	Value of the von Mangoldt function at a prime. (Contributed by Mario Carneiro, 7-Apr-2016.)
⊢ (𝑃 ∈ ℙ → (Λ‘𝑃) = (log‘𝑃))
Theorem	vmacl 27478	Closure for the von Mangoldt function. (Contributed by Mario Carneiro, 7-Apr-2016.)
⊢ (𝐴 ∈ ℕ → (Λ‘𝐴) ∈ ℝ)
Theorem	vmaf 27479	Functionality of the von Mangoldt function. (Contributed by Mario Carneiro, 7-Apr-2016.)
⊢ Λ:ℕ⟶ℝ
Theorem	efvmacl 27480	The von Mangoldt is closed in the log-integers. (Contributed by Mario Carneiro, 7-Apr-2016.)
⊢ (𝐴 ∈ ℕ → (exp‘(Λ‘𝐴)) ∈ ℕ)
Theorem	vmage0 27481	The von Mangoldt function is nonnegative. (Contributed by Mario Carneiro, 7-Apr-2016.)
⊢ (𝐴 ∈ ℕ → 0 ≤ (Λ‘𝐴))
Theorem	chpval 27482*	Value of the second Chebyshev function, or summary von Mangoldt function. (Contributed by Mario Carneiro, 7-Apr-2016.)
⊢ (𝐴 ∈ ℝ → (ψ‘𝐴) = Σ𝑛 ∈ (1...(⌊‘𝐴))(Λ‘𝑛))
Theorem	chpf 27483	Functionality of the second Chebyshev function. (Contributed by Mario Carneiro, 7-Apr-2016.)
⊢ ψ:ℝ⟶ℝ
Theorem	chpcl 27484	Closure for the second Chebyshev function. (Contributed by Mario Carneiro, 7-Apr-2016.)
⊢ (𝐴 ∈ ℝ → (ψ‘𝐴) ∈ ℝ)
Theorem	efchpcl 27485	The second Chebyshev function is closed in the log-integers. (Contributed by Mario Carneiro, 7-Apr-2016.)
⊢ (𝐴 ∈ ℝ → (exp‘(ψ‘𝐴)) ∈ ℕ)
Theorem	chpge0 27486	The second Chebyshev function is nonnegative. (Contributed by Mario Carneiro, 7-Apr-2016.)
⊢ (𝐴 ∈ ℝ → 0 ≤ (ψ‘𝐴))
Theorem	ppival 27487	Value of the prime-counting function pi. (Contributed by Mario Carneiro, 15-Sep-2014.)
⊢ (𝐴 ∈ ℝ → (π‘𝐴) = (♯‘((0[,]𝐴) ∩ ℙ)))
Theorem	ppival2 27488	Value of the prime-counting function pi. (Contributed by Mario Carneiro, 18-Sep-2014.)
⊢ (𝐴 ∈ ℤ → (π‘𝐴) = (♯‘((2...𝐴) ∩ ℙ)))
Theorem	ppival2g 27489	Value of the prime-counting function pi. (Contributed by Mario Carneiro, 22-Sep-2014.)
⊢ ((𝐴 ∈ ℤ ∧ 2 ∈ (ℤ≥‘𝑀)) → (π‘𝐴) = (♯‘((𝑀...𝐴) ∩ ℙ)))
Theorem	ppif 27490	Domain and codomain of the prime-counting function pi. (Contributed by Mario Carneiro, 15-Sep-2014.)
⊢ π:ℝ⟶ℕ0
Theorem	ppicl 27491	Real closure of the prime-counting function pi. (Contributed by Mario Carneiro, 15-Sep-2014.)
⊢ (𝐴 ∈ ℝ → (π‘𝐴) ∈ ℕ0)
Theorem	muval 27492*	The value of the Möbius function. (Contributed by Mario Carneiro, 22-Sep-2014.)
⊢ (𝐴 ∈ ℕ → (μ‘𝐴) = if(∃𝑝 ∈ ℙ (𝑝↑2) ∥ 𝐴, 0, ( -1↑(♯‘{𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝐴}))))
Theorem	muval1 27493	The value of the Möbius function at a non-squarefree number. (Contributed by Mario Carneiro, 21-Sep-2014.)
⊢ ((𝐴 ∈ ℕ ∧ 𝑃 ∈ (ℤ≥‘2) ∧ (𝑃↑2) ∥ 𝐴) → (μ‘𝐴) = 0)
Theorem	muval2 27494*	The value of the Möbius function at a squarefree number. (Contributed by Mario Carneiro, 3-Oct-2014.)
⊢ ((𝐴 ∈ ℕ ∧ (μ‘𝐴) ≠ 0) → (μ‘𝐴) = ( -1↑(♯‘{𝑝 ∈ ℙ ∣ 𝑝 ∥ 𝐴})))
Theorem	isnsqf 27495*	Two ways to say that a number is not squarefree. (Contributed by Mario Carneiro, 3-Oct-2014.)
⊢ (𝐴 ∈ ℕ → ((μ‘𝐴) = 0 ↔ ∃𝑝 ∈ ℙ (𝑝↑2) ∥ 𝐴))
Theorem	issqf 27496*	Two ways to say that a number is squarefree. (Contributed by Mario Carneiro, 3-Oct-2014.)
⊢ (𝐴 ∈ ℕ → ((μ‘𝐴) ≠ 0 ↔ ∀𝑝 ∈ ℙ (𝑝 pCnt 𝐴) ≤ 1))
Theorem	sqfpc 27497	The prime count of a squarefree number is at most 1. (Contributed by Mario Carneiro, 1-Jul-2015.)
⊢ ((𝐴 ∈ ℕ ∧ (μ‘𝐴) ≠ 0 ∧ 𝑃 ∈ ℙ) → (𝑃 pCnt 𝐴) ≤ 1)
Theorem	dvdssqf 27498	A divisor of a squarefree number is squarefree. (Contributed by Mario Carneiro, 1-Jul-2015.)
⊢ ((𝐴 ∈ ℕ ∧ 𝐵 ∈ ℕ ∧ 𝐵 ∥ 𝐴) → ((μ‘𝐴) ≠ 0 → (μ‘𝐵) ≠ 0))
Theorem	sqf11 27499*	A squarefree number is completely determined by the set of its prime divisors. (Contributed by Mario Carneiro, 1-Jul-2015.)
⊢ (((𝐴 ∈ ℕ ∧ (μ‘𝐴) ≠ 0) ∧ (𝐵 ∈ ℕ ∧ (μ‘𝐵) ≠ 0)) → (𝐴 = 𝐵 ↔ ∀𝑝 ∈ ℙ (𝑝 ∥ 𝐴 ↔ 𝑝 ∥ 𝐵)))
Theorem	muf 27500	The Möbius function is a function into the integers. (Contributed by Mario Carneiro, 22-Sep-2014.)
⊢ μ:ℕ⟶ℤ