English

$C^*-$crossed product of groupoid actions on categories

Operator Algebras 2007-10-19 v1 Category Theory

Abstract

Suppose that GG is a groupoid acting on a small category HH in the sense of \cite[Definition 4]{NOT} and H×αGH\times_\alpha G is the resulting semi-direct product category (as in \cite[Proposition 8]{NOT}). We show that there exists a subcategory HrHH_r \subseteq H satisfying some nice property called ``regularity'' such that Hr×αG=H×αGH_r \times_\alpha G = H\times_\alpha G. Moreover, we show that there exists a so-called ``quasi action'' (see Definition \ref{quasi}) β\beta of GG on C(Hr)C^*(H_r) (where C(Hr)C^*(H_r) is the semigroupoid CC^*-algebra as defined in \cite{EXE}) such that C(Hr×αG)=C(Hr)×βGC^*(H_r\times_\alpha G) = C^*(H_r)\times_\beta G (where the crossed product for β\beta is as defined in Definition \ref{cross}).

Keywords

Cite

@article{arxiv.0710.3521,
  title  = {$C^*-$crossed product of groupoid actions on categories},
  author = {Han Li},
  journal= {arXiv preprint arXiv:0710.3521},
  year   = {2007}
}

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14 pages