Imagery for Open-World Spatial Problems

In her paper ([4]), Janice Glasgow adresses many important advantages that imagery models can offer over sentential models such as predicate logic. In this response, we point out another important advantage of imagery with respect to the formulation of models. Consider the problem of reasoning about placing two-dimensional polygonal “blocks” in a space, illustrated in Figure 1. For purposes such as planning, knowledge about the blocks world is commonly formalized as rules which define the legal operations. Rules are based on symbolic features, for example, a rule may state that: