The ideas and methods taught in discrete mathematics are widely reflected in various fields of computer science and technology and related majors, from scientific calculation to information processing, from theoretical computer science to computer application technology, from computer software to computer hardware, from artificial intelligence to cognitive system, which are closely related to discrete mathematics. Because the digital electronic computer is a discrete structure, it can only deal with discrete or discrete quantitative relations. Therefore, both computer science itself and modern scientific research fields closely related to computer science and its application are faced with the problem of how to establish corresponding mathematical models for discrete structures. How to discretize the mathematical model established by continuous quantitative relationship so that it can be processed by computer.