When you write the main sentence of a paper about library management system, you need to clearly express your research purpose and the core theme of the paper. The following are subject sentence templates that some examples can refer to:

1. "This paper aims to design and develop an efficient book management system to solve the cumbersome and inefficient problems in the traditional book management process."

2. By analyzing and comparing the characteristics and performance of different library management systems, this paper aims to propose an optimized library management system model to improve the management efficiency and user satisfaction of the library.

3. "The purpose of this study is to investigate the influence of library management system on library efficiency and service quality, so as to provide strategies and suggestions for improving library management."

4. "By studying users' needs and behaviors, this paper aims to design a user-friendly book management system to provide personalized book recommendation and convenient borrowing experience. "

5. The goal of this study is to realize an advanced library management system, and improve the efficiency of library resource management and the quality of information service through technological innovation and intelligent application.

Note that the main sentence should concisely summarize your research purpose and the theme of the paper, and at the same time ensure that the research focus and innovation are accurately expressed. According to your specific research content and objectives, you can modify the above examples to make them more in line with your research topic.