In symbolic computation on computers, also known as computer algebra, keyboard and display replace the traditional pencil and paper in doing mathematical computations. Interactive computer programs, which are called computer algebra systems, allow their users to compute not only with numbers, but also with symbols, formulae, equations, and so on. Many mathematical computations such as differentiation, integration, and series expansion of functions, and inversion of matrices with symbolic entries, can be carried out quickly, with emphasis on exactness of results, and without much human effort. Computer algebra systems are powerful tools for mathematicians, physicists, chemists, engineers, technicians, psychologists, sociologists, ... , in sh...