We're all going on a summer holiday: An Exercise in Non-Cardinal Case Base Retrieval

In this paper, we present similarity metrics, which provide a seamless integration of cardinal and non-cardinal similarity measures. We show that cardinal and non-cardinal ways of measuring similarity in case bases are simply instances of the deenition of similarity metrics, and that a single deenition of the maxima of a similarity metric can be applied in both the cardinal and non-cardinal cases, to give intuitively sensible maxima in both cases. We present a number of ways of constructing new similarity metrics from existing similarity metrics. A great strength of the framework is that similarity metrics of diierent types (e.g. cardinal and non-cardinal) can be combined, and the result will still be a similarity metric (to which the deenition of maxima is still applicable). The paper is illustrated throughout by examples from a holiday case base.