The application method is: 1, with additional premise rules. If the conclusion S is derived from the given premise set γ and formula P (additional premise), then the given premise γ, P implied S can be derived. 1, using P rule and R as general premise (just like S); But it should be stated: additional premise. 2. When C is deduced, the final conclusion can be directly written as: R → C; The explanation of this step is: CP rule. The subject content of discrete mathematics is 1. Set theory includes sets and their operations, binary relations and functions, natural numbers and natural number set, and cardinality of sets. 2. Graph theory: basic concepts of graphs, Euler graphs and hamiltonian graph, matrix representation of trees and graphs, planar graphs, graph coloring, dominating sets, covering sets, independent sets and matching, weighted graphs and their applications. 3. Algebraic structure: the basic concepts of algebraic system, semigroup and singularity, group, ring and field, lattice and Boolean algebra. 4. Combinatorial mathematics: combinatorial existence theorem, basic counting formula, combinatorial counting method and combinatorial counting theorem. 5. Mathematical logic: propositional logic, first-order predicate calculus and resolution principle. Discrete mathematics is divided into three courses, namely set theory and graph theory, algebraic structure and combinatorial mathematics, and mathematical logic. The teaching method is mainly classroom teaching, supplemented by written homework after class, courseware release through the school network teaching platform and teacher-student communication.