Invariant relations, invariant functions, and loop functions

The increasing criticality of software applications, the increasing size and complexity of such applications, and the increasing reliance of software engineering paradigms on third party software assets combine to place a high premium on the ability to analyze software products to an arbitrary level of thoroughness and precision. Yet despite several decades of research, the goal of analyzing the functional properties of software products to an arbitrary level of thoroughness and precision remains unfulfilled. In this paper, we discuss the use of a relation-theoretic approach inspired from Mills' logic to analyze while loops, and we support our approach by an operational prototype tool. The proposed method and tool have applications in program comprehension, reverse engineering, program verification, software maintenance, and programmer education.