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Article Dans Une Revue SIAM Journal on Discrete Mathematics Année : 2021

Shellings and Sheddings Induced by Collapses

Résumé

We say that a pure simplicial complex K of dimension d satisfies the removal-collapsibility condition if K is either empty or K becomes collapsible after removing β~d(K;Z2) facets, where β~d(K;Z2) denotes the dth reduced Betti number. In this paper, we show that if the link of each face of a pure simplicial complex K (including the link of the empty face which is the whole K) satisfy the removal-collapsibility condition, then the second barycentric subdivision of K is vertex decomposable and in particular shellable. This is a higher dimensional generalization of a result of Hachimori, who proved that that if the link of each vertex of a pure 2-dimensional simplicial complex K is connected, and K becomes simplicially collapsible after removing χ~(K) facets, where χ~(K) denotes the reduced Euler characteristic, then the second barycentric subdivision of K is shellable. For the proof, we introduce a new variant of decomposability of a simplicial complex, stronger than vertex decomposability, which we call star decomposability. This notion may be of independent interest.

Dates et versions

hal-04501837 , version 1 (12-03-2024)

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Citer

Thomas Magnard, Michael Skotnica, Martin Tancer. Shellings and Sheddings Induced by Collapses. SIAM Journal on Discrete Mathematics, 2021, 35 (3), pp.1978-2002. ⟨10.1137/19M1290826⟩. ⟨hal-04501837⟩
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