Thanks to the powerful tools borrowed from commutative algebra, we show a general approach to determine the prime spectra of some coordinate rings by examples. As we determine the spectrum of the Gaussian integers, a proof of the famous two squares theorem emerges without tricky techniques.
A reading guidance of the first part of J. P. Serre’s A Course in Arithmetic
应用代数工具，对模 \(m\) 剩余类环 \(\mathbb Z / m \mathbb Z\) 的乘法结构做出流畅的刻画，作为推论导出原根存在定理．面向有朴素抽象代数基础的 OI/XCPC 算法竞赛选手和学习过本科抽象代数课程的同学．
我们详细重述并证明 Simultaneous Triangularization (H. Radjavi and P. Rosenthal) 中的 Burnside 定理及其相关推论．
现场赛公式模板库，亦可作为小而精的总结性学习材料参考．无需单独成文或暂不完善的内容会放在这里．
OI/XCPC 常见算法为主，渐进符号、约数函数、整除分块嵌套与杜教筛．
《同分异构体计数从入门到精通》（不是）
