DATABASE FUNDAMENTALS
DATA WAREHOUSING AND DATA MINING
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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If a rule is infrequent, its specialized rules are also infrequent
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If a rule is infrequent, its generalized rules are also infrequent
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Both a and b
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None of the above
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Detailed explanation-1: -It assumes that the frequent itemset has all its non-empty subsets being frequent. This property is called the Apriori property. Thus according to it if the itemset is infrequent then all its supersets will also be infrequent.
Detailed explanation-2: -The apriori algorithm gives you frequent itemsets. Its basis is the apriori property which we can explain in the following way: Suppose an item set you have has a support value less than the necessary support value. Then, the subsets of this itemset would also have less support value than required.
Detailed explanation-3: -It was later improved by R Agarwal and R Srikant and came to be known as Apriori. This algorithm uses two steps “join” and “prune” to reduce the search space. It is an iterative approach to discover the most frequent itemsets.
Detailed explanation-4: -Apriori principle allows us to prune all the supersets of an itemset which does not satisfy the minimum threshold condition for support. For example, if Milk, Notebook does not satisfy our threshold of minsup, an itemset with any item added to this will never cross the threshold too.
Detailed explanation-5: -The Apriori algorithm uses frequent itemsets to generate association rules, and it is designed to work on the databases that contain transactions. With the help of these association rule, it determines how strongly or how weakly two objects are connected.