Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Computing K-theory and Ext for graph C*-algebras   K-theory and Ext are computed for the C*-algebra C*(E) of any countable
directed graph E. The results generalize the K-theory computations of Raeburn
and Szymanski and the Ext computations of Tomforde for row-finite graphs. As a
consequence, it is shown that if A is a countable {0,1} matrix and E_A is the
graph obtained by viewing A as a vertex matrix, then C*(E_A) is not necessarily
Morita equivalent to the Exel-Laca algebra O_A.

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The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-fin
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The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat
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The categories of this paper are: alg-geom
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The categories of this paper are: comp-gas
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The categories of this paper are: nucl-ex
6
The categories of this paper are: astro-ph
9
The categories of this paper are: nlin
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The categories of this paper are: funct-an
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The categories of this paper are: solv-int
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The categories of this paper are: atom-ph
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The categories of this paper are: acc-phys