Key Words-Software engineering ; software lifecycle ; language independent methodology ; abstract program ; abstract machine ; problem solving environment. Abstract-This paper presents an environment and a methodology for system modelling. The environment provides a powerful, language independent, infrastructure for the transformation of problems to programs. The methodology is designed to account for the representational distortions found throughout the various phases of problem refinement and resolution. It is thus useful within the software lifecycle and can form the infrastructure for the development of Expert Systems.