Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On The Structure Of The Chan-Paton Factors For D-Branes In Type II
  Orientifolds   We determine the structure of the Chan-Paton factors of the open strings
ending on space filling D-branes in Type II orientifolds. Through the analysis,
we obtain a rule concerning possible distribution of O-plane types. The result
is applied to classify the topology of D-branes in terms of Fredholm operators
and K-theory, deriving a proposal made earlier and extending it to more general
cases. It is also applied to compactifications with N=1 supersymmetry in
four-dimensions. We adapt and develop the language of category in this context,
and use it to describe some decay channels.

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The categories of this paper are: physics
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The categories of this paper are: acc-phys
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The categories of this paper are: ao-sci
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The categories of this paper are: adap-org
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The categories of this paper are: math-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: cond-mat
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The categories of this paper are: stat
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The categories of this paper are: q-fin
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The categories of this paper are: patt-sol
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The categories of this paper are: comp-gas
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The categories of this paper are: chao-dyn
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The categories of this paper are: supr-con
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The categories of this paper are: bayes-an
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The categories of this paper are: alg-geom