Generic initial ideals and exterior algebraic shifting of the join of simplicial complexes

dc.creatorMurai, Satoshi
dc.date2005-06-15
dc.date2006-12-14
dc.date.accessioned2026-07-07T07:34:32Z
dc.date.available2026-07-07T07:34:32Z
dc.descriptionIn this paper, the relation between algebraic shifting and join which was conjectured by Eran Nevo will be proved. Let $σ$ and $τ$ be simplicial complexes and $σ* τ$ their join. Let $J_σ$ be the exterior face ideal of $σ$ and $Δ(σ)$ the exterior algebraic shifted complex of $σ$. Assume that $σ* τ$ is a simplicial complex on $[n]=\{1,2,...,n\}$. For any $d$-subset $S \subset [n]$, let $m_{\preceq_{rev} S}(σ)$ denote the number of $d$-subsets $R \in σ$ which is equal to or smaller than $S$ w.r.t. the reverse lexicographic order. We will prove that $m_{\preceq_{rev} S}(Δ({σ* τ}))\geq m_{\preceq_{rev} S}(Δ({Δ(σ)} * {Δ(τ)}))$ for all $S \subset [n]$. To prove this fact, we also prove that $m_{\preceq_{rev} S}(Δ(σ))\geq m_{\preceq_{rev} S}(Δ({Δ_ϕ(σ)}))$ for all $S\subset [n]$ and for all non-singular matrices $ϕ$, where $Δ_ϕ(σ)$ is the simplicial complex defined by $J_{Δ_ϕ(σ)}=\init(ϕ(J_σ))$.
dc.descriptionImprove presentations, 8 pages, to appear in Ark. Mat
dc.identifierhttps://arxiv.org/abs/math/0506298
dc.identifierhttp://arxiv.org/abs/math/0506298
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/119799
dc.subjectCombinatorics
dc.subjectCommutative Algebra
dc.subject13F55; 05E99
dc.titleGeneric initial ideals and exterior algebraic shifting of the join of simplicial complexes
dc.typetext

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