A set-partition of a List is a partitioning of the list into a finite number of non-empty disjoint pieces whose union is the original list.
i1 : setPartition {2,3,5}
o1 = {{{2, 3, 5}}, {{2, 3}, {5}}, {{2, 5}, {3}}, {{2}, {3, 5}}, {{2}, {3}, {5}}}
o1 : List
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The set-partitions of $n$ is the collection of set-partitions of the set $\{1,\ldots,n\}$.
i2 : setPartition 4
o2 = {{{1, 2, 3, 4}}, {{1, 2, 3}, {4}}, {{1, 2, 4}, {3}}, {{1, 2}, {3, 4}}, {{1, 2}, {3}, {4}}, {{1, 3}, {2, 4}}, {{1, 3, 4},
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{2}}, {{1, 3}, {2}, {4}}, {{1, 4}, {2, 3}}, {{1}, {2, 3, 4}}, {{1}, {2, 3}, {4}}, {{1, 4}, {2}, {3}}, {{1}, {2, 4}, {3}},
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{{1}, {2}, {3, 4}}, {{1}, {2}, {3}, {4}}}
o2 : List
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The object setPartition is a method function.