Results 1  10
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28
CuntzKrieger algebras of directed graphs
, 1996
"... We associate to each rowfinite directed graph E a universal CuntzKrieger C  algebra C (E), and study how the distribution of loops in E affects the structure of C (E). We prove that C (E) is AF if and only if E has no loops. We describe an exit condition (L) on loops in E which allow ..."
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Cited by 150 (33 self)
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We associate to each rowfinite directed graph E a universal CuntzKrieger C  algebra C (E), and study how the distribution of loops in E affects the structure of C (E). We prove that C (E) is AF if and only if E has no loops. We describe an exit condition (L) on loops in E which allows us to prove an analogue of the CuntzKrieger uniqueness theorem and give a characterisation of when C (E) is purely infinite. If the graph E satisfies (L) and is cofinal, then we have a dichotomy: if E has no loops, then C (E) is AF; if E has a loop, then C (E) is purely infinite.
The CuntzKrieger algebras of rowfinite graphs
, 1999
"... Abstract. We prove versions of the fundamentaltheorems about CuntzKrieger algebras for the C ∗algebras of rowfinite graphs: directed graphs in which each vertex emits at most finitely many edges. Special cases of these results have previously been obtained using various powerful machines; our mai ..."
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Cited by 95 (19 self)
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Abstract. We prove versions of the fundamentaltheorems about CuntzKrieger algebras for the C ∗algebras of rowfinite graphs: directed graphs in which each vertex emits at most finitely many edges. Special cases of these results have previously been obtained using various powerful machines; our main point is that direct methods yield sharper results more easily. Contents 1. The C∗algebras of graphs 309 2. The gaugeinvariant uniqueness theorem 311 3. The CuntzKrieger uniqueness theorem 313 4. Ideals in graph algebras 316
Higher rank graph C*algebras
, 2000
"... Building on recent work of Robertson and Steger, we associate a C ∗ –algebra to a combinatorial object which may be thought of as a higher rank graph. This C ∗ –algebra is shown to be isomorphic to that of the associated path groupoid. Various results in this paper give sufficient conditions on the ..."
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Cited by 58 (11 self)
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Building on recent work of Robertson and Steger, we associate a C ∗ –algebra to a combinatorial object which may be thought of as a higher rank graph. This C ∗ –algebra is shown to be isomorphic to that of the associated path groupoid. Various results in this paper give sufficient conditions on the higher rank graph for the associated C ∗ –algebra to be: simple, purely infinite and AF. Results concerning the structure of crossed products by certain natural actions of discrete groups are obtained; a technique for constructing rank 2 graphs from “commuting” rank 1 graphs is given.
Higher rank graph C∗algebras
, 2000
"... Building on recent work of Robertson and Steger, we associate a C*algebra to a combinatorial object which maybe thought of as a higher rank graph. This C*algebra is shown to be isomorphic to that of the associated path groupoid. Various results in this paper give sufficient conditions on the highe ..."
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Cited by 26 (5 self)
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Building on recent work of Robertson and Steger, we associate a C*algebra to a combinatorial object which maybe thought of as a higher rank graph. This C*algebra is shown to be isomorphic to that of the associated path groupoid. Various results in this paper give sufficient conditions on the higher rank graph for the associated C*algebra to be: simple, purely infinite and AF. Results concerning the structure of crossed products by certain natural actions of discrete groups are obtained; a technique for constructing rank 2 graphs from "commuting" rank 1 graphs is given.
Graph inverse semigroups, groupoids and their
 C ∗ algebras, J. Operator Theory
"... Abstract. There is now a substantial literature on graph C ∗algebras. Under a locally finite condition on a countable, directed graph, Kumjian, Pask, Raeburn, Renault showed that the C ∗algebra of the graph can be realized as the C ∗algebra of the path groupoid, i.e. the groupoid determined by th ..."
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Cited by 25 (2 self)
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Abstract. There is now a substantial literature on graph C ∗algebras. Under a locally finite condition on a countable, directed graph, Kumjian, Pask, Raeburn, Renault showed that the C ∗algebra of the graph can be realized as the C ∗algebra of the path groupoid, i.e. the groupoid determined by the infinite paths in the graph. In the present paper, we remove the local finiteness requirement. The path groupoid in the general context is obtained through the universal groupoid of a certain inverse semigroup associated with the graph. This inverse semigroup is called the graph inverse semigroup, and graph representations turn out to be just representations of this inverse semigroup. A certain reduction of the universal groupoid gives the path groupoid of the graph, and its C ∗algebra is isomorphic to the C ∗algebra of the graph. The unit space of the path groupoid contains the infinite paths of the graph, but also contains some finite paths. We show that, as in the locally finite case, the path groupoid is always amenable, and we give a groupoid proof of a recent theorem of W. Szymanski, characterizing when a graph C ∗algebra is simple. 1.
The C*Algebras of rowfinite graphs
, 2000
"... We prove versions of the fundamental theorems about CuntzKrieger algebras for the C*algebras of rowfinite graphs: directed graphs in which each vertex emits at most finitely many edges. Special cases of these results have previously been obtained using various powerful machines; our main point is ..."
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Cited by 20 (5 self)
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We prove versions of the fundamental theorems about CuntzKrieger algebras for the C*algebras of rowfinite graphs: directed graphs in which each vertex emits at most finitely many edges. Special cases of these results have previously been obtained using various powerful machines; our main point is that direct methods yield sharper results more easily.
A class of C∗algebras generalizing both graph algebras and homeomorphism C∗algebras I, . . .
, 2003
"... We introduce a new class of C∗algebras, which is a generalization of both graph algebras and homeomorphism C ∗algebras. This class is very large and also very tractable. We prove the socalled gaugeinvariant uniqueness theorem and the CuntzKrieger uniqueness theorem, and compute the Kgroups of ..."
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Cited by 19 (5 self)
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We introduce a new class of C∗algebras, which is a generalization of both graph algebras and homeomorphism C ∗algebras. This class is very large and also very tractable. We prove the socalled gaugeinvariant uniqueness theorem and the CuntzKrieger uniqueness theorem, and compute the Kgroups of our algebras.
C*Algebras of Directed Graphs and Group Actions
, 1997
"... Given a free action of a group G on a directed graph E we show that the crossed product of C*(E), the universal C*algebra of E, by the induced action is strongly Morita equivalent to C*(E/G). Since every connected graph E may be expressed as the quotient of a tree T by an action of a free group G ..."
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Cited by 15 (5 self)
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Given a free action of a group G on a directed graph E we show that the crossed product of C*(E), the universal C*algebra of E, by the induced action is strongly Morita equivalent to C*(E/G). Since every connected graph E may be expressed as the quotient of a tree T by an action of a free group G we may use our results to show that C*(E) is strongly Morita equivalent to the crossed product C0 (@T ) \Theta G, where @T is a certain 0dimensional space canonically associated to the tree.
Simplicity of C ∗ algebras associated to higherrank graphs
"... Abstract. We prove that if Λ is a rowfinite kgraph with no sources, then the associated C ∗algebra is simple if and only if Λ is cofinal and satisfies Kumjian and Pask’s Condition (A). We prove that Condition (A) is equivalent to a suitably modified version of Robertson and Steger’s original nonp ..."
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Cited by 10 (6 self)
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Abstract. We prove that if Λ is a rowfinite kgraph with no sources, then the associated C ∗algebra is simple if and only if Λ is cofinal and satisfies Kumjian and Pask’s Condition (A). We prove that Condition (A) is equivalent to a suitably modified version of Robertson and Steger’s original nonperiodicity condition (H3) which in particular involves only finite paths. We also characterise both cofinality and aperiodicity of Λ in terms of ideals in C ∗ (Λ). 1.
Flow equivalence of graph algebras
 Ergod. Th. & Dynam. Sys
"... Abstract. This paper explores the effect of various graphical constructions upon the associated graph C ∗algebras. The graphical constructions in question arise naturally in the study of flow equivalence for topological Markov chains. We prove that outsplittings give rise to isomorphic graph algebr ..."
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Cited by 8 (2 self)
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Abstract. This paper explores the effect of various graphical constructions upon the associated graph C ∗algebras. The graphical constructions in question arise naturally in the study of flow equivalence for topological Markov chains. We prove that outsplittings give rise to isomorphic graph algebras, and insplittings give rise to strongly Morita equivalent C ∗algebras. We generalise the notion of a delay as defined in [D] to form indelays and outdelays. We prove that these constructions give rise to Morita equivalent graph C ∗algebras. We provide examples which suggest that our results are the most general possible in the setting of the C ∗algebras of arbitrary directed graphs. 1.