Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Spacetime of Double Field Theory: Review, Remarks, and Outlook   We review double field theory (DFT) with emphasis on the doubled spacetime
and its generalized coordinate transformations, which unify diffeomorphisms and
b-field gauge transformations. We illustrate how the composition of generalized
coordinate transformations fails to associate. Moreover, in dimensional
reduction, the O(d,d) T-duality transformations of fields can be obtained as
generalized diffeomorphisms. Restricted to a half-dimensional subspace, DFT
includes `generalized geometry', but is more general in that local patches of
the doubled space may be glued together with generalized coordinate
transformations. Indeed, we show that for certain T-fold backgrounds with
non-geometric fluxes, there are generalized coordinate transformations that
induce, as gauge symmetries of DFT, the requisite O(d,d;Z) monodromy
transformations. Finally we review recent results on the \alpha' extension of
DFT which, reduced to the half-dimensional subspace, yields intriguing
modifications of the basic structures of generalized geometry.

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The categories of this paper are: adap-org
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The categories of this paper are: dg-ga
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The categories of this paper are: cmp-lg
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The categories of this paper are: ao-sci
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: acc-phys
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: solv-int
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The categories of this paper are: plasm-ph
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The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
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The categories of this paper are: bayes-an
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The categories of this paper are: eess