Goal-Directed Reasoning with ACE-SSM

Past research shows that the goal of knowledge-based systems (KBSs) is not only to produce a solution to a problem situation they face, but also to construct, implicitly or explicitly, a situationspecific model (SSM) that explicates the rationale behind that solution. This paper focuses on how KBSs can benefit from the availability of explicit goal knowledge that reflects the underlying structure (ontology) of SSMs constructed for an application task. It first shows how goal knowledge can be captured. Then, it explains how ACE-SSM -an architecture for constructing explicit SSMs -uses this knowledge to direct the construction of explicit SSMs. Finally, it discusses benefits that KBSs can derive from the availability of explicit SSMs and their underlying goal knowledge. Some of these benefits pertain to ways to simplify the construction and maintenance of KBSs through reuse, while others have to do with ways to endow KBSs with more robust problem-solving and explanation capabilities. These benefits are illustrated using concrete examples.