At its most basic level, the interactive software system is usually defined as a user interface with user classes. It models the user interface requirements. The user classes are varied, based on the potentially conflicting requirements and expectations. In addition, there are other systems in the working environment that the interactive system would have to interface with which furthermore adds to the complexity (Shneiderman, 2010). In the case of multi-disciplinary development in interactive projects, ‘User Centred Design’ UCD process is considered to be helpful in addressing the issues of changes in a much more just in time fashion (Dabs et al., 2009). Understanding interactive system design can also be done with user behavioural models and more and these discussions are presented in the literature review section of this thesis in the second chapter. The second chapter presents the background on the decision support and interactive systems and acts as the literature review of this paper. The use of formal methods has also been shown to be helpful in the design of interactive systems where formal methods is not part of the traditional UCD process, so they can be incorporated in a way that be beneficial (Dabs et al., 2009). Software engineering methodology is usually based on a recommended development process proceeding through several phases, which are that of Analysis, Specification, Design, Coding, Unit Testing, Integration and System Testing and Maintenance (Dabbs et al., 2009). Formal methods can be a foundation for describing complex systems and also a foundation for reasoning about systems. It helps in providing support for program development and is a complimentary approach to methodology. Chapter 3 will present detailed evidence on existing research on the topic.