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A database has four transactions. Let minimum support = 50% and minimum confidence = 50%
Transaction_Id Items bought
T100 A, B, C
T200 A, C
T300 A, D
T400 B, E, F

Find all frequent item sets using apriori algorithm. List strong association rules.

1 Answer
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Apriori Algorithm

The given Minimum Support = 50 %

The Number of Transactions = 4

Therefore,

The Minimum Support = $ 0.5 \times 4 = 2 $

Step 1 - Calculate the Minimum Count for each Item.

Therefore,

Items Minimum Count
A 3
B 2
C 2
D 1
E 1
F 1

Step 2 - Delete the items that do not have a minimum support count of 2.

Therefore, Items D, E, and F are deleted.

Items Minimum Count
A 3
B 2
C 2

Step 3 - Combine 2-items and find out the Minimum Count of the occurrences of the 2-items.

Items Minimum Count
A,B 1
A,C 2
B,C 1

Now, got the only item-set {A,C} that is frequent.

Step 4 - Generate Association Rules from the frequent itemset discovered in the above step - 3.

Rule 1 - {A} => {C}

$$ Confidence = \frac{Support\{A,C\}}{Support\{A\}} = \frac 23 \times 100 = 66.67\ \% $$

Rule 2 - {C} => {A}

$$ Confidence = \frac{Support\{A,C\}}{Support\{C\}} = \frac 22 \times 100 = 100\ \% $$

The given Minimum Confidence = 50 %

Therefore,

This shows that all the above Association Rules are Strong.

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