Hat are the closed items . what are the closed items . what are closed itemsets what are closed class items what are closed frequent itemsets what is closed itemset in data mining

In data mining, a closed itemset is a frequent itemset $X$ for which there is no superset $Y$ such that $Y$ has the same support count as $X$. In simpler terms, if you add any item to a closed itemset, the support count (frequency) of the new, larger itemset will always be strictly less than that of the original closed itemset.

This concept is used to reduce the number of frequent itemsets generated, as it eliminates redundant itemsets that have the same support as their subsets.