Verification of real-time programs by a knowledge-based strategy

Abstract

A verification system for real-time programs must provide a means of showing that the programs are logically correct and of proving that all timing constraints are met. To prove a program correct, according to traditional methods, all possible execution sequences (i.e. traces) must be shown to satisfy the specifications. That, however, will lead to the exponential explosion of the traces. This paper adopts an Artificial Intelligence technique to verify real-time programs, and proposes a method by which the real-time programs are proved just in a so-called “Reasonable Trace Space” (RTS). The RTS is a subset of the set of all traces (in short, the ATS) and is determined by a knowledge base which is provided by the program designer or a software verification expert. If a real-time program is proved correct in the RTS (which is much smaller than the ATS), it can be concluded that it is error free in the sense of the knowledge base. A knowledge-based trace-generation algorithm which enumerates all reasonable traces and a trace-verification algorithm which decides whether a trace is correct or not, are presented. Their performances are also analyzed.