DescentSet from Permutation
The positions where the word falls.
The statistics Descents and MajorIndex are the size and the sum of this set — which is the reduction worth having: a statistic of a map's output rather than a fresh walk.
Called as CombinatorialMap(x, "DescentSet"). The head's page has its examples.
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Explore
Each element of Permutation at a size, and its image, applied in your browser; sizes past 7 are not offered.
Properties
Transport a statistic
Pick a statistic on Finset. Its distribution over the images of Permutation at each size is computed, and compared with the 323 statistics on Permutation: those that share it are the ones the map sends it to, as far as the sizes computed show.
No statistic is declared on Finset.