Application of the goal invariant to the structuring of programs

Abstract

Functional rather than structural approach to conversion of a two-exit loop into a <u>while</u> loop is presented. The functions computed by the corresponding exits are formally specified and their union is analyzed to reveal the cause of its loop nonrealizability. The latter is removed by either redefining the domain/range of the constituent functions or by inclusion of the loop postludes into the loop specification. None of these methods changes the functionality of the original program because no new variables are introduced.