唯一分解整环相关知识解析
1. 幂和与牛顿恒等式
在环 (R) 中,设 (\alpha_1, \cdots, \alpha_{\ell} \in R),定义多项式 (f = (X - \alpha_1)(X - \alpha_2) \cdots (X - \alpha_{\ell}) \in R[X])。对于 (j \geq 0),定义幂和 (s_j = \sum_{i = 1}^{\ell} \alpha_i^j)。在环 (R((X^{-1}))) 中有:
(\frac{D(f)}{f} = \sum_{i = 1}^{\ell} \frac{1}{(X - \alpha_i)} = \sum_{j = 1}^{\infty} s_{j - 1}X^{-j}),其中 (D(f)) 是 (f) 的形式导数。
继续上述内容,可推导出牛顿恒等式。若 (f = X^{\ell} + f_1X^{\ell - 1} + \cdots + f_{\ell}),其中 (f_1, \cdots, f_{\ell} \in R),则有:
- (s_1 + f_1 = 0)
- (s_2 + f_1s_1 + 2f_2 = 0)
- (s_3 + f_1s_2 + f_2s_1 + 3f_3 = 0)
- (\cdots)
- (s_{\ell} + f_1s_{\ell - 1} + \cdots + f_{\ell - 1}s_1 + \ell f_{\ell} = 0)
- (s_{j + \ell} + f_1s_{j + \ell - 1} + \cdots + f_{\ell - 1}s_{j + 1} + f_{\ell}s_j =