# Frequent pattern

The frequent pattern is a pattern that occurs again and again (frequently) in a dataset.

A pattern can be a set of items, substructures, and subsequences etc.

## Closed frequent itemset

If itemset has no superset with the same frequency

## Max frequent itemset

If itemset does not have any frequent supersets.

## Examples of Frequent pattern, Closed frequent itemset, Max frequent itemset

It is compulsory to set a min_support that can defines which itemset is frequent. An itemset is frequent if its support is greater or equal to min_support. Suppose the minimum support is 1 and there are two transactions T1 and T2

**T1 =** {A1, A2, A3, ……………….A19, A20}

**T2 =** {A1, A2, A3, …….A9, A10}

**Set of closed frequent itemset / Closed pattern :**

**T1 =** {A1, A2, A3, ……………….A19, A20}

**The frequency **of T1 is 1

**T2 =** {A1, A2, A3, …….A9, A10}

**The frequency **of T2 is 2

**Set of max frequent itemset / max pattern :**

**T1 =** {A1, A2, A3, ……………….A19, A20}

T1 is representing max pattern.