Detective novels were categorized as follows: 1. Classics: Holmes as the representative emphasized scientific methods and logical reasoning. 2. The modern school, represented by Agatha Christie, paid attention to the complexity and multiple possibilities of the plot, often using suspense and mystery techniques. 3. Detective novel school: Karl Popper as the representative emphasized the application of scientific methods and logical reasoning. 4. The socialists, represented by James Joyce, focused on the discussion of social problems and social reality, emphasizing human nature and psychological analysis. 5. Suspense School: With Stephen King as the representative, it pays attention to the twists and turns of the plot and the psychological description of the characters, emphasizing the revelation of human nature and social reality. 6. Sci-fi: William gibson as the representative, focusing on the fusion of sci-fi elements and reasoning elements, emphasizing the exploration and imagination of the future. 7. Psychology School: John Emsley, as the representative, focuses on the description and analysis of the character's psychology, emphasizing the deep exploration of human nature. 8. Horror Faction: John Le Carre as the representative focuses on the use of horror and horror elements, emphasizing the criticism of human nature and social reality.