On Moving Objects in Dynamic Domains

In the physical world, an object is a moving object if its position changes over time. In a symbolic dynamic system such as a computer program or a blocks world, what are the moving objects? In this paper, we propose a definition, consider ways to generate moving objects and their "positions." We also introduce the flow graph of a moving object. It depicts the "trajectory" of the object, thus should be useful when planning to achieve a goal that involves moving some objects around.