From Object-Oriented Specification to Implementation: A Formal Refinement Methodology.

Traditionally, software development models use different methods and techniques in each phase from specification through design to implementation. Significant changes in the representations between phases have been common. The formal development method based on formal specification and stepwise development has been suggested to reduce the change in representation. The formal development method consists of a formal specification and verified design. In the formal specification step, a formal specification language is used to specify an accurate, consistent, and complete system. Vienna Development Method (VDM) is one of the most widely used formal specification languages. A verified design guides the development of the system from specification to executable code. A refinement method is used in VDM for that purpose. The use of the object-oriented paradigm is another important trend in software engineering. Initially, object-oriented methods were applied primarily during the implementation phase using object-oriented languages. Eiffel is an object-oriented programming language which has many strong facilities such as assertions and genericity. Numerous object-oriented specification languages exist, including object-oriented extensions to VDM. We defined Object-VDM to help remove limitations from existing object-oriented VDM languages. In this dissertation, we investigate a formal development method in the object-oriented environment since limited research hss been done in the area. We defined a refinement method that refines an Object-VDM specification to Eiffel code. There are three stages in this refinement: data refinement, operation refinement, and structure refinement. In data refinement, the mathematical data models in Object-VDM are converted to Eiffel data structures by creating Eiffel libraries. We proved the correctness of the conversion. In operation refinement, we modified and added rules to the original refinement to obtain Eiffel code. Object-oriented features are converted in the structure refinement step. In summary, this research provides a refinement method in object-oriented environments. Specifically, the refinement converts Object-VDM specifications to Eiffel codes

Metamodel-based model conformance and multiview consistency checking

Model-driven development, using languages such as UML and BON, often makes use of multiple diagrams (e.g., class and sequence diagrams) when modeling systems. These diagrams, presenting different views of a system of interest, may be inconsistent. A metamodel provides a unifying framework in which to ensure and check consistency, while at the same time providing the means to distinguish between valid and invalid models, that is, conformance. Two formal specifications of the metamodel for an object-oriented modeling language are presented, and it is shown how to use these specifications for model conformance and multiview consistency checking. Comparisons are made in terms of completeness and the level of automation each provide for checking multiview consistency and model conformance. The lessons learned from applying formal techniques to the problems of metamodeling, model conformance, and multiview consistency checking are summarized

Nonlinear regression in tax evasion with uncertainty: a variational approach

One of the major problems in today's economy is the phenomenon of tax evasion. The linear regression method is a solution to find a formula to investigate the effect of each variable in the final tax evasion rate. Since the tax evasion data in this study has a great degree of uncertainty and the relationship between variables is nonlinear, Bayesian method is used to address the uncertainty along with 6 nonlinear basis functions to tackle the nonlinearity problem. Furthermore, variational method is applied on Bayesian linear regression in tax evasion data to approximate the model evidence in Bayesian method. The dataset is collected from tax evasion in Malaysia in period from 1963 to 2013 with 8 input variables. Results from variational method are compared with Maximum Likelihood Estimation technique on Bayeisan linear regression and variational method provides more accurate prediction. This study suggests that, in order to reduce the tax evasion, Malaysian government should decrease direct tax and taxpayer income and increase indirect tax and government regulation variables by 5% in the small amount of changes (10%-30%) and reduce direct tax and income on taxpayer and increment indirect tax and government regulation variables by 90% in the large amount of changes (70%-90%) with respect to the current situation to reduce the final tax evasion rate

Applying inspection to object-oriented software

The benefits of the object-oriented paradigmare widely cited. At the same time, inspection is deemed to be the most cost-effective means of detecting defects in software products. Why then, is there no published experience, let alone quantitative data, on the application of inspection to object-oriented systems? We describe the facilities of the object-oriented paradigm and the issues that these raise when inspecting object-oriented code. Several problems are caused by the disparity between the static code structure and its dynamic runtime behaviour. The large number of small methods in object-oriented systems can also cause problems. We then go on to describe three areas which may help mitigate problems found. Firstly, the use of various programming methods may assist in making object-oriented code easier to inspect. Secondly, improved program documentation can help the inspector understand the code which is under inspection. Finally, tool support can help the inspector to analyse the dynamic behaviour of the code. We conclude that while both the object-oriented paradigm and inspection provide excellent benefits on their own, combining the two may be a difficult exercise, requiring extensive support if it is to be successful