Question

According to lehman software is devided into

Answer 1

In his 1980 article, Lehman qualified the application of such laws by distinguishing between three categories of software:

An S-program is written according to an exact specification of what that program can doA P-program is written to implement certain procedures that completely determine what the program can do (the example mentioned is a program to play chess)An E-program is written to perform some real-world activity; how it should behave is strongly linked to the environment in which it runs, and such a program needs to adapt to varying requirements and circumstances in that environment