PeakSet

The interior positions that rise then fall.

PeakSet(Permutation)The interior positions that rise then fall.

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.
• Its size is the Peaks statistic, exactly as DescentSet's is Descents.

Examples

Basic #

the one-line word $231$

live ↗

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

About

Examples	1