Section 5.1.5 presented various ways of defining negatively correlated patterns. Consider Definition 5.3: "Suppose that itemsets \(X\) and \(Y\) are both frequent, that is, \(\sup (X) \geq\) min_sup and \(\sup (Y) \geq\) min_sup, where min_sup is the minimum support threshold. If \((P(X \mid Y)+\) \(P(Y \mid X)) / 2<\epsilon\), where \(\epsilon\) is a negative pattern threshold, then pattern \(X \cup Y\) is a negatively correlated pattern." Design an efficient pattern growth algorithm for mining the set of negatively correlated patterns.

Section 5.1.5

All the methods presented so far in this chapter have been for mining frequent patterns. Sometimes, however, it is interesting to find patterns that are rare instead of frequent, or patterns that reflect a negative correlation between items. These patterns are respectively referred to as rare patterns and negative patterns. In this subsection, we consider various ways of defining rare patterns and negative patterns, which are also useful to mine.