SYSTEM DECOMPOSITION. Decomposition is the process of dividing the system into smaller sub- system parts. This is a convenient way of representing, viewing, and understanding the relationships among subsystems. By decomposing a system, we can present the overall system as a hierarchy and view the relationships between subordinate and higher-level subsystems. Each subordinate subsystem performs one or more specific functions to help achieve the overall objective of the higher-level system. Figure 1-2 shows an automobile decomposed into four primary subsystems: the fuel subsystem, the propulsion sub- system, the electrical subsystem, and the braking subsystem. Each contributes in a unique way to the sys- tem’s objective, conveyance. These second-level subsystems are decomposed further into two or more subordinate subsystems at a third level. Each third-level subsystem performs a task in direct support of its second-level system.