Full Abstraction at Package Boundaries of Object-Oriented Languages

We develop a fully abstract trace-based semantics for sets of classes in object-oriented languages, in particular for Java-like sealed packages. Our approach enhances a standard operational semantics such that the change of control between the package and the client context is made explicit in terms of interaction labels. By using traces over these labels, we abstract from the data representation in the heap, support class hiding, and provide fully abstract package denotations. The soundness and completeness of our approach is proven using innovative simulation techniques.