# 刘维尔数

${\displaystyle 0<\left|x-{\frac {p}{q}}\right|<{\frac {1}{q^{n}}}}$

## 基本性质

${\displaystyle \left|x-{\frac {p}{q}}\right|=\left|{\frac {c}{d}}-{\frac {p}{q}}\right|=\left|{\frac {cq-dp}{dq}}\right|\geq {\frac {1}{dq}}>{\frac {1}{2^{n-1}q}}\geq {\frac {1}{q^{n}}}}$

## 刘维尔常数

${\displaystyle c=\sum _{j=1}^{\infty }10^{-j!}=0.110001000000000000000001000\ldots }$

${\displaystyle p_{n}=\sum _{j=1}^{n}10^{n!-j!},\quad q_{n}=10^{n!}}$

${\displaystyle \left|c-{\frac {p_{n}}{q_{n}}}\right|=\sum _{j=n+1}^{\infty }10^{-j!}=10^{-(n+1)!}+10^{-(n+2)!}+{}\cdots <10\cdot 10^{-(n+1)!}\leq {\Big (}10^{-n!}{\Big )}^{n}={\frac {1}{{q_{n}}^{n}}}.}$

## 超越性

### 证明

${\displaystyle \left\vert \alpha -{\frac {p}{q}}\right\vert >{\frac {A}{q^{n}}}}$

${\displaystyle 0

${\displaystyle \left\vert \alpha -{\frac {p}{q}}\right\vert \leq {\frac {A}{q^{n}}}\leq A<\min \left(1,{\frac {1}{M}},\left\vert \alpha -\alpha _{1}\right\vert ,\left\vert \alpha -\alpha _{2}\right\vert ,\ldots ,\left\vert \alpha -\alpha _{m}\right\vert \right)}$

${\displaystyle f(\alpha )-f(p/q)=(\alpha -p/q)\cdot f'(x_{0})}$

${\displaystyle \left\vert (\alpha -p/q)\right\vert =\left\vert f(\alpha )-f(p/q)\right\vert /\left\vert f'(x_{0})\right\vert =\left\vert f(p/q)/f'(x_{0})\right\vert \,}$

${\displaystyle f}$ 是多项式，所以

${\displaystyle \left\vert f(p/q)\right\vert =\left\vert \sum _{i=0}^{n}c_{i}p^{i}q^{-i}\right\vert ={\frac {\left\vert \sum _{i=0}^{n}c_{i}p^{i}q^{n-i}\right\vert }{q^{n}}}\geq {\frac {1}{q^{n}}}}$

${\displaystyle \left\vert \alpha -p/q\right\vert =\left\vert f(p/q)/f'(x_{0})\right\vert \geq 1/(Mq^{n})>A/q^{n}\geq \left\vert \alpha -p/q\right\vert }$

${\displaystyle \exists n\in \mathbb {Z} ,A>0\forall p,q\left(\left\vert x-{\frac {p}{q}}\right\vert >{\frac {A}{q^{n}}}\right)}$

${\displaystyle \left|x-{\frac {a}{b}}\right|<{\frac {1}{b^{m}}}={\frac {1}{b^{r+n}}}={\frac {1}{b^{r}b^{n}}}\leq {\frac {1}{2^{r}}}{\frac {1}{b^{n}}}\leq {\frac {A}{b^{n}}}}$

## 参考文献

1. ^ Liouville, Joseph. Mémoires et communications. Comptes rendus de l'Académie des Sciences. [2023-01-02]. （原始内容存档于2023-02-21）.