Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Consistency Conditions for Branes at Orbifold Singularities   We discuss consistency conditions for branes at orbifold singularities. The
conditions have a world-sheet interpretation in terms of tadpole cancellation
and a space-time interpretation in terms of anomalies. As examples, we consider
type II and type I branes on $C^2/Z_M$ orbifolds. We give orientifold
constructions of phases of type I or heterotic string theory, involving
branches with extra tensor multiplets, which arise when small SO(32) instantons
sit on orbifold singularities.

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The categories of this paper are: cs
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The categories of this paper are: atom-ph
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The categories of this paper are: physics
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The categories of this paper are: quant-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: q-fin
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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: gr-qc
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The categories of this paper are: comp-gas
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The categories of this paper are: econ
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The categories of this paper are: hep-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: math
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The categories of this paper are: nlin