The Utility Problem Analysed: A Case-Based Reasoning Perspective

In case-based reasoning (CBR) there are compelling arguments in support of large case-bases; greater target problem coverage, better solution quality, improved system efficiency. However a problem known as the utility problem dictates that the last of these arguments is not necessarily true. In fact, adding more cases to an already "saturated" case-base will reduce rather than improve system efficiency. Thus, there is a trade-off situation in which adding cases to improve coverage and quality is pitted against efficiency degradation. This paper discusses the utility problem from a case-based reasoning perspective, examining its root causes in an experimental CBR system.