Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Open Strings and Dualities   In the fruitful interplay between gauge fields and strings and in many
conjectured M-theory dualities, open strings play a prominent role. We review
the construction of open-string descendants (un-orientifolds) of closed-string
theories admitting a generalized orientation reversal involution. We then
specialize the construction to some classes of non-supersymmetric models in
D=10 that have been recently considered in the context of duality without
supersymmetry. We also discuss the propagation of open and unoriented strings
on the NS pentabrane (N5-brane). This background is a prototype of the
configurations of branes and orientifold planes that represent a powerful
alternative to the geometric engineering of Supersymmetric Yang-Mills Theories.
The resulting description of D-branes in non-trivial backgrounds looks very
different from the one naively expected. In particular the very distinction
between different Dp-branes becomes ambiguous in the presence of strong
curvature effects.

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The categories of this paper are: chem-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: solv-int
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The categories of this paper are: nlin
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The categories of this paper are: chao-dyn
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The categories of this paper are: eess
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The categories of this paper are: cmp-lg
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The categories of this paper are: stat
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The categories of this paper are: plasm-ph
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The categories of this paper are: physics
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The categories of this paper are: bayes-an
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The categories of this paper are: nucl-th
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The categories of this paper are: econ
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The categories of this paper are: acc-phys
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The categories of this paper are: funct-an
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The categories of this paper are: math-ph