Analysis of compliance, consistency and completeness of requirements.

The consistency of the requirements can be checked by using a formal model. To this end the requirements need to be transformed into a formal model of the behavior of the system (based on use case descriptions). The properties or rules should be formalized in some logic and then they can be checked with the model. Often this can be done automatically. There are two possibilities: either the model satisfies all the properties or at least one property does not hold. In the latter situation the requirements are inconsistent and a counter example has to be produced. If we have a model of the system in this stage, it is possible to generate test cases from this model that can be used in later stages when the software is constructed. These test cases can be used to check if the constructed software demonstrates the required behavior.

Although this approach is in principle applicable, it is time consuming and a more superficial approach might be appropriate. In that situation the user requirements are inspected by experts in order to discover ambiguities and inconsistencies. Sometimes the customer has already made a (rough) architectural model of the system. Then it is possible to check inconsistencies between this model and the required properties.

• Business requirements: goals of the system;
• Functional requirements: use cases and constraints on the behavior of the system;
• Extra functional requirements: performance and development constraints.

• Diagnosis with ambiguities, open questions, counter examples for rules and quantitative judgments;
• Additional: a system model and test cases.

• Analysis of the requirements of a national reference system. In future many sectors will use this system as backbone for their sector systems. If possible this diagnosis should lead to future certification of the system and the related systems.
• Research and guard the test methodology of a national e-ticketing system that leads to “Complete and sound requirements & test scenarios”. The development, validation and testing of the system is fully outsourced to a huge consortium.
• Validation of company rules for requirements analysis and compliance checking based on international accepted standards.