Programming Pattern-based Composition in Golog

Pattern-based composition is rather complex and need formal treatments. This paper demonstrates an approach based on logic programming language Golog, whose logical foundations roots in the Situation Calculus. The first step is formalizing design patterns by a set of fluents, actions and corresponding axioms in the Situation Calculus. Based on the formal specification of the underlying patterns, we program their composition in Golog. The program constructs available in Golog provide us with flexible and expressive means for pattern composition. Since the composed specifications in Golog can be regress into the Situation Calculus formulas by Golog interpreter, the properties of underlying patterns can be preserved in their composition. As a case study, we formalize and compose the Mediator pattern and Observer pattern.