In combinatorial mathematics, a combination's an un-ordered collection of distinct elements, usually of a prescribed size and taken from a given set. (An ordered collection of distinct elements would sometimes be called a permutation, but that term's ambiguous. }}) Given such a set S, a combination of elements of S's just a subset of S, where, as always for (sub)sets the order of the elements isn't taken into account (two lists with the same elements in different orders are considered to be the… (More on Combination)