Last updated on:December 9th, 2018,

Apriori principles in data mining, Downward closure property, Apriori pruning principle

Apriori principles

In this tutorial, we will try to answer the following questions;

  1. What is Downward closure property of frequent patterns?
  2. Example of Downward closure property of frequent patterns?
  3. What is Apriori pruning principle?
  4. Example of Apriori pruning principle.

Downward closure property of frequent patterns

All subset of any frequent itemset must also be frequent.

Example:

If Tea, Biscuit, Coffee is a frequent itemset, then we can say that all of the following itemsets are frequent;

  • Tea
  • Biscuit
  • Coffee
  • Tea,  Biscuit
  • Tea, Coffee
  • Biscuit, Coffee

Apriori pruning principle

If an itemset is infrequent, its superset should not be generated for getting the frequent itemset.

Examples of Apriori pruning principle

If Tea, Biscuit is a frequent itemset and Coffee is not frequent itemset, then we can say that all of the following itemsets are frequent;

  • Tea
  • Biscuit
  • Tea, Biscuit

 

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