Data abstraction in Prolog/KR

Data abstraction and inheritance, some of the most important features in constructing a large, clean software system, in a logic programming language Prolog/KR, an expansion of Prolog, are described. First two kinds of processes are added; one is called NPO, which is mainly used to implement a generator, the other is called CPO, which is mainly used to implement an abstract data object. Then synchronization features are added to implement abstract data types that can be used concurrently. Using this feature it is possible to employ pipes for communications among processes. Finally, inheritance mechanism is added to define hierarchies among objects.