Basically association rule works in two steps:
(1) Generating item sets that pass a minimum support
threshold.
(2) Generating rules that pass a minimum confidence
threshold.
Association Rule Mining (ARM) obtains a set of rules which
indicate that the consequent of a rule is likely to apply if the
antecedent applies [10]. To generate such rules, the first step is to
determine the support for sets of items (I) that may be present in
the data set, i.e., the frequency with which each combination of
items occurs. After eliminating those I for which the support fails
to meet a given minimum support threshold, the remaining large
“I” can be used to produce ARs of the form A B, where A and
B are disjoint subsets of a large I. The ARs generated are usually
pruned according to some notion of confidence in each AR.
However to achieve this pruning, it is always necessary to first
identify the “large” I contained in the input data. This in turn
requires an effective storage structure. One of the efficient data
storage mechanisms for itemset storage is T-tree [15].