SwapReturnsAndLastDescent from DyckPath
An involution exchanging the number of returns with the length of the last descent.
FindStat's Mp00118, the specialization to Dyck paths of the map of Elizalde and Rubey. It keeps the number of ups before each down that is neither a return nor in the last descent.
Called as CombinatorialMap(x, "SwapReturnsAndLastDescent"). The head's page has its examples.
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Properties
Transport a statistic
Pick a statistic on DyckPath. Its distribution over the images of DyckPath at each size is computed, and compared with the 171 statistics on DyckPath: those that share it are the ones the map sends it to, as far as the sizes computed show.
FindStat Mp00118
swap returns and last descent
Matched by value: our map agrees with FindStat's image on each of the 196 rows of size at most 6 we can read (0 unread; its table has 1200 rows).
BijectionGraded mapInvolutionas FindStat records them, checked by FindStat's contributors.
| Object | Image |
|---|---|
[1,0] | [1,0] |
[1,0,1,0] | [1,1,0,0] |
[1,1,0,0] | [1,0,1,0] |
[1,0,1,0,1,0] | [1,1,1,0,0,0] |
Data from FindStat, the combinatorial statistic finder; the page at findstat.org/Mp00118 has the rest.