3 . interpret the contents both on the pile and difference in precious mirror of the four elements ( si yuan yu jian ) and the arithmetical triangle in treat on the arithmetical triangle ( traite du triangle arithmetique ) . both works are the much earlier books study the combinatorial identities in system 三、用现代组合符号解释了中国朱世杰的《四元玉鉴》中垛积招差部分和帕斯卡的《论算术三角形》内容，指出这两部著作是东、西方对组合恒等式研究的较早的系统论著。
