The order of the (123, 132)-avoiding stack sort
Let s be West's deterministic stack-sorting map.A well-known result is that every length n permutation is sorted with n -1 iterations of s.In 2020, Defant introduced the notion of highly-sorted permutationspermutations obtained by applying slightly less than n -1 iterations of s.In 2023, Choi & Choi extended this notion to generalized stack-sorting maps s , where we relax the condition of becoming sorted to the analogous condition of becoming periodic with respect to s .While periodicity seems counterintuitive in the context of sorting, it arises naturally in these restrictive forms, where the map is studied as an operator with properties rather than a means to "sort" permutations in the usual sense.In this work, we introduce the notion of minimally-sorted permutations as an antithesis to Defant's highlysorted permutations, and show that the order of the (123, 132)-avoiding stack-sorting map is 2 n-1 2 .
Authors
- Owen Zhang
Institutions
- Yale University (US)
Publication Details
- Journal
- Enumerative Combinatorics and Applications
- Published
- 2025-04-04
- DOI
- https://doi.org/10.54550/eca2025v5s3r18
- Primary Topic
- Logic, programming, and type systems
- Type
- article
- Field-Weighted Citation Impact
- 0.00