# Locally standard torus actions and sheaves over Buchsbaum posets

Research paper by **Anton Ayzenberg**

Indexed on: **24 Feb '15**Published on: **24 Feb '15**Published in: **Mathematics - Algebraic Topology**

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#### Abstract

We consider a sheaf of exterior algebras on a simplicial poset $S$ and
introduce a notion of homological characteristic function. Two natural objects
are associated with these data: a graded sheaf $\mathcal{I}$ and a graded
cosheaf $\widehat{\Pi}$. When $S$ is a homology manifold, we prove the
isomorphism $H^{n-1-p}(S;\mathcal{I})\cong H_{p}(S;\widehat{\Pi})$ which can be
considered as an extension of the Poincare duality. In general, there is a
spectral sequence $E^2_{p,q}\cong H^{n-1-p}(S;\mathcal{U}_{n-1+q}\otimes
\mathcal{I})\Rightarrow H_{p+q}(S;\widehat{\Pi})$, where $\mathcal{U}_*$ is the
local homology stack on $S$. This spectral sequence, in turn, extends
Zeeman--McCrory spectral sequence. This sheaf-theoretical result is applied to
toric topology. We consider a manifold $X$ with a locally standard action of a
compact torus and acyclic proper faces of the orbit space. A principal torus
bundle $Y$ is associated with $X$, so that $X\cong Y/\sim$. The orbit type
filtration on $X$ is covered by the topological filtration on $Y$. We prove
that homological spectral sequences associated with these two filtrations are
isomorphic in many nontrivial positions.