Generalized recursive atom ordering and equivalence to CL-shellability

Fuente: arXiv
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Main Authors: Hersh, Patricia, Stadnyk, Grace
Format: Preprint
Published: 2022
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author Hersh, Patricia
Stadnyk, Grace
author_facet Hersh, Patricia
Stadnyk, Grace
contents Björner and Wachs introduced CL-shellability as a technique for studying the topological structure of order complexes of partially ordered sets (posets). They also introduced the notion of recursive atom ordering, and they proved that a finite bounded poset is CL-shellable if and only if it admits a recursive atom ordering. In this paper, a generalization of the notion of recursive atom ordering is introduced. A finite bounded poset is proven to admit such a generalized recursive atom ordering if and only if it admits a traditional recursive atom ordering. This is also proven equivalent to admitting a CC-shelling (a type of shelling introduced by Kozlov) with a further property called self-consistency. Thus, CL-shellability is proven equivalent to self-consistent CC-shellability. As an application, the uncrossing posets, namely the face posets for stratified spaces of planar electrical networks, are proven to be dual CL-shellable.
format Preprint
id arxiv_https___arxiv_org_abs_2212_03949
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Generalized recursive atom ordering and equivalence to CL-shellability
Hersh, Patricia
Stadnyk, Grace
Combinatorics
05E45, 06A07
Björner and Wachs introduced CL-shellability as a technique for studying the topological structure of order complexes of partially ordered sets (posets). They also introduced the notion of recursive atom ordering, and they proved that a finite bounded poset is CL-shellable if and only if it admits a recursive atom ordering. In this paper, a generalization of the notion of recursive atom ordering is introduced. A finite bounded poset is proven to admit such a generalized recursive atom ordering if and only if it admits a traditional recursive atom ordering. This is also proven equivalent to admitting a CC-shelling (a type of shelling introduced by Kozlov) with a further property called self-consistency. Thus, CL-shellability is proven equivalent to self-consistent CC-shellability. As an application, the uncrossing posets, namely the face posets for stratified spaces of planar electrical networks, are proven to be dual CL-shellable.
title Generalized recursive atom ordering and equivalence to CL-shellability
topic Combinatorics
05E45, 06A07
url https://arxiv.org/abs/2212.03949