Teacher Chen Daoxu, known as "Uncle Xu", teaches discrete mathematics to freshmen in the Institute of Software. Xu Ye's prestige in the Soft Institute is very high. At that time, before each exam, a large number of students in Renren.com forwarded Xu Ye's head. I like discrete mathematics very much. The content of this course itself is very interesting, plus my profound knowledge and humorous language. As a freshman, I benefited a lot. From deciphering German codes in World War II to cellular automata, from infinite hotels in 123 to the continuum hypothesis, I still remember many details clearly.