Revision as of 22:54, 12 November 2006 by JBL (talk | contribs)

A multiset is a slight generalization of the notion of a set. A set is defined by whether or not each object is an element. A multiset is defined not just by its elements, but also by how many times each element is contained. In other words, a multiset is a set where duplication of elements is allowed.

For example, $\{1, 1, 2, 3\} \neq \{1, 2, 3\}$ as multisets.

Note that the order of the elements is unimportant, so $\displaystyle \{1, 1, 2, 3\}= \{3, 1, 2, 1\}$.

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