Exploiting domain knowledge to detect outliers

We present a novel definition of outlier whose aim is to embed an available domain knowledge in the process of discovering outliers. Specifically, given a background knowledge, encoded by means of a set of first-order rules, and a set of positive and negative examples, our approach aims at singling out the examples showing abnormal behavior. The technique here proposed is unsupervised, since there are no examples of normal or abnormal behavior,...