Smooth Programs and Languages.

A smooth program is defined to be one which is "go to"-free in the sense that it can be represented by a flowchart consisting only of concatenation, alternation, and interation elements. Three methods of eliminating the "go to" statement from a program have been proposed: (1) the introduction of additional Boolean variables or the equivalent recomputation of certain quantities in the program, (2) the use of recursive procedure calls, and (3) replacement of the "go to" statement by a restricted form of the "go to" such as the "exit" or "leave" statement. We show that only the first of these is capable of transforming a non-smooth program into a smooth one, since strict application of the recursive procedure method requires the use of a so-called "null procedure" which is in fact also a restricted form of the "go to." (Author)