Question 7 True or False with one sentence explanation. 1. Given that {a,b,c,d}

Question

Question 7 True or False with one sentence explanation. 1. Given that {a,b,c,d} is a frequent itemset, {a,b} is always a frequent itemset. 2. Given that {a,b}, (b,c) and {a,c} arc frequent iternsets, {a,b,c} is always frequent. 3. Given that the support of {a,b} is 20 and the support of {b,c} is 30, the support of {b} is larger than 20 but smaller than 30. 4. Given that the support of {b,c} is 30 and {b} is a maximal frequent itemset, the count of minsup is equal to 30. 5. Given that the support of {a,b,c} is 20 and the support of {b,c} is 30, {b,c} is a closed itemset.

Explanation / Answer

1. False          Frequent itemsets are the itemsets that occur frequently irrespective of sub itemsets

2.True            if the all the sub itemsets occur frequent then the combines itemset is maximal frequent set here a,b,c is maximal frequent itemsets.   All the maximal frequent itemsets are frequent itemsets but not vice versa.

3.True            given a,b 's average support is 20 and b,c 's average support is 30. Here as b is common and the support is increased on replacing a with c. So the b is more than 20 and less than 30

4.False

5.False    --an itemset is closed if none of its immediate supersets has the same support as the itemset.

Conclusion:

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