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= Welcome to MWiki = | = Welcome to MWiki = | ||
== Theorems of the month == | == Theorems of the month == | ||
− | === | + | === Counting theorem for algebraic numbers === |
− | + | The number <math>\mathbb{A}(m, n)</math> of algebraic numbers of polynomial or series degree <math>m</math> and thus in general for the Riemann zeta function <math>\zeta</math> asymptotically satisfies the equation <math>\mathbb{A}(m, n) = \widetilde{\zeta(\grave{m})}\,z(m){{(2n+1)}^{m}}\left( n+\mathcal{O}({_e}n) \right)</math>, where <math>z(m)</math> is the average number of zeros of a polynomial or series. | |
==== Proof: ==== | ==== Proof: ==== | ||
− | < | + | The case <math>m = 1</math> requires by <ref name="Scheid">[[w:Harald Scheid|<span class="wikipedia">Scheid, Harald</span>]]: ''Zahlentheorie'' : 1st Ed.; 1991; Bibliographisches Institut; Mannheim; ISBN 9783411148417, p. 323.</ref> the error term <math>\mathcal{O}({_e}n n)</math> and represents the number <math>4{+}_{k=1}^{n}{\varphi (k)}-1</math> by the <math>\varphi</math>-function. For <math>m > 1</math>, the divisibility conditions neither change the error term <math>\mathcal{O}({_e}n)</math> nor the leading term. Polynomials or series such that <math>\text{gcd}({a}_{0}, {a}_{1}, ..., {a}_{m}) \ne 1</math> are excluded by <math>1/\zeta(\grave{m})</math>: The latter is given by taking the product over the prime numbers <math>p</math> of all <math>(1 - {p}^{-\grave{m}})</math> absorbing here multiples of <math>p</math> and representing sums of geometric series.<math>\square</math> |
− | === | + | === Brocard's theorem === |
− | + | It holds that <math>\{(m, n) \in {}^{\omega} \mathbb{N}^2 : n! + 1 = m^2\} = \{(5, 4), (11, 5), (71, 7)\}.</math> | |
==== Proof: ==== | ==== Proof: ==== | ||
− | + | From <math>n! = \acute{m}\grave{m}</math>, it follows that <math>m = \hat{r} \pm 1</math> für <math>r \in {}^{\omega} \mathbb{N}^{*}</math> and <math>n \ge 3</math>. Thus <math>n! = \hat{r}(\hat{r}\pm2) = 8s(\hat{s} \pm 1)</math> holds for <math>s \in {}^{\omega} \mathbb{N}^{*}</math>. Let <math>2^q \mid n!</math> and <math>2^{\grave{q}} \nmid n!</math> for maximal <math>q \in {}^{\omega} \mathbb{N}^{*}</math>. Therefore <math>n! = 2^q(\hat{u} + 1)</math> holds for <math>u \in {}^{\omega} \mathbb{N}^{*}</math> and necessarily <math>n! = 2^q(2^{q-2} \pm 1)</math>. Then the prime factorisation of <math>n!</math> requires <math>n \le 7</math> giving the claim.<math>\square</math> | |
− | === | + | === Reversion theorem of Taylor series === |
− | + | For <math>y \in f(\mathbb{D}), y(a) = b</math> and <math>y^{\prime}(a) \ne 0</math>, [[w:Lagrange_inversion_theorem#Lagrange–Bürmann_formula|<span class="wikipedia">Bürmann's theorem</span>]] yields:<div style="text-align:center;"><math>f^{-1}(y) = a + \tilde{n} {\LARGE{\textbf{+}}}_{m=1}^n{\widetilde{m}{\tilde{\varepsilon}}^{\acute{m}}(y - b)^m({\tilde{u}}^{\acute{m}k})^T(f(\varepsilon u^k + a)^{-m})}+\mathcal{O}(\varepsilon^n).\square</math></div> | |
== Recommended reading == | == Recommended reading == | ||
[https://en.calameo.com/books/003777977258f7b4aa332 Nonstandard Mathematics] | [https://en.calameo.com/books/003777977258f7b4aa332 Nonstandard Mathematics] | ||
+ | |||
+ | == References == | ||
+ | <references /> | ||
[[de:Hauptseite]] | [[de:Hauptseite]] |
Revision as of 00:22, 18 July 2024
Welcome to MWiki
Theorems of the month
Counting theorem for algebraic numbers
The number [math]\displaystyle{ \mathbb{A}(m, n) }[/math] of algebraic numbers of polynomial or series degree [math]\displaystyle{ m }[/math] and thus in general for the Riemann zeta function [math]\displaystyle{ \zeta }[/math] asymptotically satisfies the equation [math]\displaystyle{ \mathbb{A}(m, n) = \widetilde{\zeta(\grave{m})}\,z(m){{(2n+1)}^{m}}\left( n+\mathcal{O}({_e}n) \right) }[/math], where [math]\displaystyle{ z(m) }[/math] is the average number of zeros of a polynomial or series.
Proof:
The case [math]\displaystyle{ m = 1 }[/math] requires by [1] the error term [math]\displaystyle{ \mathcal{O}({_e}n n) }[/math] and represents the number [math]\displaystyle{ 4{+}_{k=1}^{n}{\varphi (k)}-1 }[/math] by the [math]\displaystyle{ \varphi }[/math]-function. For [math]\displaystyle{ m \gt 1 }[/math], the divisibility conditions neither change the error term [math]\displaystyle{ \mathcal{O}({_e}n) }[/math] nor the leading term. Polynomials or series such that [math]\displaystyle{ \text{gcd}({a}_{0}, {a}_{1}, ..., {a}_{m}) \ne 1 }[/math] are excluded by [math]\displaystyle{ 1/\zeta(\grave{m}) }[/math]: The latter is given by taking the product over the prime numbers [math]\displaystyle{ p }[/math] of all [math]\displaystyle{ (1 - {p}^{-\grave{m}}) }[/math] absorbing here multiples of [math]\displaystyle{ p }[/math] and representing sums of geometric series.[math]\displaystyle{ \square }[/math]
Brocard's theorem
It holds that [math]\displaystyle{ \{(m, n) \in {}^{\omega} \mathbb{N}^2 : n! + 1 = m^2\} = \{(5, 4), (11, 5), (71, 7)\}. }[/math]
Proof:
From [math]\displaystyle{ n! = \acute{m}\grave{m} }[/math], it follows that [math]\displaystyle{ m = \hat{r} \pm 1 }[/math] für [math]\displaystyle{ r \in {}^{\omega} \mathbb{N}^{*} }[/math] and [math]\displaystyle{ n \ge 3 }[/math]. Thus [math]\displaystyle{ n! = \hat{r}(\hat{r}\pm2) = 8s(\hat{s} \pm 1) }[/math] holds for [math]\displaystyle{ s \in {}^{\omega} \mathbb{N}^{*} }[/math]. Let [math]\displaystyle{ 2^q \mid n! }[/math] and [math]\displaystyle{ 2^{\grave{q}} \nmid n! }[/math] for maximal [math]\displaystyle{ q \in {}^{\omega} \mathbb{N}^{*} }[/math]. Therefore [math]\displaystyle{ n! = 2^q(\hat{u} + 1) }[/math] holds for [math]\displaystyle{ u \in {}^{\omega} \mathbb{N}^{*} }[/math] and necessarily [math]\displaystyle{ n! = 2^q(2^{q-2} \pm 1) }[/math]. Then the prime factorisation of [math]\displaystyle{ n! }[/math] requires [math]\displaystyle{ n \le 7 }[/math] giving the claim.[math]\displaystyle{ \square }[/math]
Reversion theorem of Taylor series
For [math]\displaystyle{ y \in f(\mathbb{D}), y(a) = b }[/math] and [math]\displaystyle{ y^{\prime}(a) \ne 0 }[/math], Bürmann's theorem yields:
Recommended reading
References
- ↑ Scheid, Harald: Zahlentheorie : 1st Ed.; 1991; Bibliographisches Institut; Mannheim; ISBN 9783411148417, p. 323.