This paper describes a semi-automatic transformation from object-oriented conceptual models to logical theories. By associating a logical theory with a conceptual model, we are able to combine the best of both worlds. On one hand, the object-oriented software development paradigm is recognized to be well-suited to build maintainable and-communicable conceptual models. On the other hand, the logical programming paradigm offers very powerful and semantically founded concepts to represent knowledge and the use of logical inference systems makes it possible to prototype solutions to computational tasks: Since our method makes this mapping from conceptual models to logical theories traceable, dealing with the evolution of the problem domain and ...