Subdivisions of lower Eulerian posets

Fuente: arXiv
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Main Author: Stapledon, Alan
Format: Preprint
Published: 2025
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author Stapledon, Alan
author_facet Stapledon, Alan
contents There is a natural notion of a subdivision of a lower Eulerian poset called a strong formal subdivision, which abstracts the notion of a polyhedral subdivision of a polytope, or a proper, surjective morphism of fans. We show that there is a canonical bijection between strong formal subdivisions and triples consisting of a lower Eulerian poset, a corresponding rank function, and a non-minimal element such that the join with any other element exists. The bijection uses the non-Hausdorff mapping cylinder construction introduced by Barmak and Minian. A corresponding bijection for $CW$-posets is given, as well as an application to computing the $cd$-index of an Eulerian poset. A companion paper explores applications to Kazhdan-Lusztig-Stanley theory.
format Preprint
id arxiv_https___arxiv_org_abs_2511_16608
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Subdivisions of lower Eulerian posets
Stapledon, Alan
Combinatorics
06A07
There is a natural notion of a subdivision of a lower Eulerian poset called a strong formal subdivision, which abstracts the notion of a polyhedral subdivision of a polytope, or a proper, surjective morphism of fans. We show that there is a canonical bijection between strong formal subdivisions and triples consisting of a lower Eulerian poset, a corresponding rank function, and a non-minimal element such that the join with any other element exists. The bijection uses the non-Hausdorff mapping cylinder construction introduced by Barmak and Minian. A corresponding bijection for $CW$-posets is given, as well as an application to computing the $cd$-index of an Eulerian poset. A companion paper explores applications to Kazhdan-Lusztig-Stanley theory.
title Subdivisions of lower Eulerian posets
topic Combinatorics
06A07
url https://arxiv.org/abs/2511.16608