A set-like object in which order is ignored, but multiplicity is explicitly significant. Therefore, multisets {1, 2, 3} and {2, 1, 3} are equivalent, but {1, 1, 2, 3} and {1, 2, 3} differ. The number of multisets of length k on n symbols is called n multichoose k, denoted ((n k)).

aggregate | ball picking | binomial coefficient | choose | collection | combination | list | multichoose | multinomial coefficient | permutation | set | string