A transaction database contains ten transactions as shown be
Solution
An association rule is an implication of the form AB,
where A and B are frequent itemsets in a transaction database and AB=.
The rule AB can be interpreted as “if itemset A occurs in a transaction,
then itemset B will also likely occur in the same transaction”.
By such information, market personnel can place itemsets A and B within close proximity,
which may encourage the sale of these items together and develop discount strategies
based on such association/correlation found in the data.
Item: attribute=value pair or simply value
usually attributes are converted into binary flags for
each value, e.g. product=“d” is written as “d”
Itemset I : a subset of possible items
Example: I = {A,B,E} (order unimportant)
Transaction: (TID, itemset)
Support of an itemset
sup( I ) = no. of transactions t that support
(that is contain) I
In example database:
sup ({A,B,E}) = 2, sup ({B,C}) = 4
Frequent itemset I is one with at least the
minimum support count
sup( I ) >= minsup
