Comparison Between Model Fields and Abstract Predicates

To modularly specify and verify object oriented programs on some abstract level, we need abstraction techniques to hide the implementation details of the classes. Model fields and abstract predicates are two most important approaches to address the requirements. In this paper, we mainly compare their expressiveness. We develop two translation algorithms, which can translate a program with model fields based specification to one with abstract predicates based specification. We prove that the translation algorithms are correct, and the resulting specifications are well-encapsulated and well-formed. This shows that the abstract predicates technique is more expressive. On the other hand, the model fields based specifications are more user friendly and useful in automatic verification. In addition, we discuss the different characteristics of the two approaches in framing, inheritance, and recursion.