Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Asymmetric Orbifolds and Higher Level Models   I introduce a class of string constructions based on asymmetric orbifolds
leading to level two models. In particular, I derive in detail various models
with gauge groups $E_6$ and SO(10), including a four generation $E_6$ model
with two adjoint representations. The occurrence of multiple adjoint
representations is a generic feature of the construction. In the course of
describing this approach, I will address the problem of twist phases in higher
twisted sectors of asymmetric orbifolds.

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The categories of this paper are: funct-an
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The categories of this paper are: chem-ph
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The categories of this paper are: q-bio
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The categories of this paper are: hep-lat
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The categories of this paper are: nlin
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The categories of this paper are: nucl-th
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The categories of this paper are: plasm-ph
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The categories of this paper are: eess
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The categories of this paper are: econ
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The categories of this paper are: adap-org
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The categories of this paper are: comp-gas
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The categories of this paper are: acc-phys
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The categories of this paper are: cond-mat
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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: astro-ph