The law of diminishing returns represents a special case of the application of Amdahl's law. The passage provides an example of a scenario where Amdahl's law represents the law of diminishing returns. In this scenario one is running a fixed sized computation that will use all available processors to their capacity and is considering what sort of return can be achieved by adding more processors to a machine. Applying Amdahl's law tells us that each new processor added to the system will add less usable power than the previous. In other words, each new processor yields diminishing returns.