Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: C*-algebras associated to graphs of groups   To a large class of graphs of groups we associate a C*-algebra universal for
generators and relations. We show that this C*-algebra is stably isomorphic to
the crossed product induced from the action of the fundamental group of the
graph of groups on the boundary of its Bass-Serre tree. We characterise when
this action is minimal, and find a sufficient condition under which it is
locally contractive. In the case of generalised Baumslag-Solitar graphs of
groups (graphs of groups in which every group is infinite cyclic) we also
characterise topological freeness of this action. We are then able to establish
a dichotomy for simple C*-algebras associated to generalised Baumslag-Solitar
graphs of groups: they are either a Kirchberg algebra, or a stable
Bunce-Deddens algebra.

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The categories of this paper are: eess
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The categories of this paper are: math-ph
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The categories of this paper are: supr-con
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The categories of this paper are: cond-mat
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The categories of this paper are: cs
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The categories of this paper are: mtrl-th
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The categories of this paper are: quant-ph
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The categories of this paper are: funct-an
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The categories of this paper are: hep-th
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The categories of this paper are: solv-int
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The categories of this paper are: patt-sol
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The categories of this paper are: q-bio
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The categories of this paper are: gr-qc
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The categories of this paper are: q-fin
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The categories of this paper are: q-alg
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The categories of this paper are: atom-ph