A formal method for software maintenance

Petri net theory allows a system to be modeled by a Petri net, an abstract formal model of information flow characterised by controls and constraints. Analysis of the Petri net can then reveal important information about the structure and dynamic behaviour of the modeled system, which can be used to evaluate the modeled system and suggest improvements or changes. This feature can be used in software maintenance. We propose a method for developing a Predicate/Transition net (PrT net) for software maintenance, whereby, software components are reverse engineered and annotated with formal predicates, transformed into a PrT net, and analysed on the PrT net. The advantage of the method is that inconsistencies of a program can be detected and revealed precisely.