Algebraic Shifting and Basic Constructions on Simplicial Complexes

dc.creatorNevo, Eran
dc.date2003-03-19
dc.date2006-02-23
dc.date.accessioned2026-07-07T06:35:36Z
dc.date.available2026-07-07T06:35:36Z
dc.descriptionWe try to understand the behavior of exterior algebraic shifting with respect to basic constructions on simplicial complexes, like union and join. In particular we give a complete combinatorial description of the shifting of a disjoint union, and more generally of a union along a simplex, in terms of the shifting of its components. As a corollary, we prove the following, conjectured by Kalai: $Δ(K \cup L) = Δ(Δ(K) \cup Δ(L))$, where $K,L$ are complexes, $\cup$ means disjoint union, and $Δ$ is the exterior shifting operator. We give an example showing that replacing the operation 'union' with the operation 'join' in the above equation is wrong, disproving a conjecture made by Kalai. We adopt a homological point of view on the algebraic shifting operator, which is used throughout this work.
dc.descriptionFinal version: 24 pages, no figures. Proof of Proposition 4.5 improved, minor changes
dc.identifierhttps://arxiv.org/abs/math/0303233
dc.identifierhttp://arxiv.org/abs/math/0303233
dc.identifierJ. Algeb. Combi., 22 (2005), 411-433
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/99843
dc.subjectCombinatorics
dc.subjectCommutative Algebra
dc.subject05E99; 13D99; 13F55
dc.titleAlgebraic Shifting and Basic Constructions on Simplicial Complexes
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