DescentSet

The positions where the word falls.

DescentSet(Permutation)The positions where the word falls.

Typed signatures

Type	Package	Applies
(permutation) -> finset	combinatorics	always

Domain: Combinatorial maps

Details

• Takes a Permutation and returns a Finset — a typed map, so a wrong carrier is a type error rather than a wrong answer.
• 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.

Examples

Basic #

the one-line word $231$

live ↗

In$\mathrm{DescentSet}({\operatorname{Permutation}}([2, 3, 1]))$Out$\operatorname{Finset}(\operatorname{Tuple}(3,\bigl\lbrack2\bigr\rbrack))$

About

Examples	1