“…Then, it is possible to classify the results obtained after the projection operation in different groups of rules potentially useful for the user. Four sets of rules can be defined (Liu et al, 1999): conforming rules (if both the antecedent and consequence are consistent with the user expectation), unexpected consequence rules (showing discovered rules which consequences are different from those expected), unexpected antecedent rules (showing other antecedents that can lead to the required result), and both-side unexpected rules (which are not known by the user or are not mentioned in its expectations).…”