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WeakExceedancePartition from Permutation ​

The coarsest set partition containing every arc from i to π(i) with i ≤ π(i).

Permutation → SetPartition

FindStat's Mp00240, the weak exceedance partition. Not injective.

Called as CombinatorialMap(x, "WeakExceedancePartition"). The head's page has its examples.

Live

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 SetPartition. 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.

FindStat Mp00240

weak exceedance partition

Matched by value: our map agrees with FindStat's image on each of the 873 rows of size at most 6 we can read (0 unread; its table has 1200 rows).

SurjectionGraded mapas FindStat records them, checked by FindStat's contributors.

The set partition induced by the weak exceedances of a permutation.
ObjectImage
[1]{{1}}
[1,2]{{1},{2}}
[2,1]{{1,2}}
[1,2,3]{{1},{2},{3}}

Data from FindStat, the combinatorial statistic finder; the page at findstat.org/Mp00240 has the rest.