Integrating case-based and rule-based reasoning to meet multiple design constraints

Although case-based reasoning (CBR) was introduced as an alternative to rul e-based reasoning (RBR), there is a growing interest in integrating it with other reasoning paradigms, including RBR. New hybrid approaches are being piloted to achieve new synergies and improve problem-solving capabilities. In our approach to integration, CBR is used to satisfy multiple numeric con straints, and RBR allows the performance of "what if" analysis needed for c reative design. The domain of our investigation is nutritional menu planning. The task of d esigning nutritious, yet appetizing, menus is one at which human experts co nsistently outperform computer systems. Tailoring a menu to the needs of an individual requires satisfaction of multiple numeric nutrition constraints plus personal preference goals and aesthetic criteria. We first constructed and evaluated independent CBR and RBR menu planning sy stems, then built a hybrid system incorporating the strengths of each syste m. The hybrid outperforms either single strategy system, designing superior menus, while synergistically providing functionality that neither single s trategy system could provide. In this paper, we present our hybrid approach , which has applicability to other design tasks in which both physical cons traints and aesthetic criteria must be met.