Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Non-geometric backgrounds in string theory   This review provides an introduction to non-geometric backgrounds in string
theory. Starting from a discussion of T-duality, geometric and non-geometric
torus-fibrations are reviewed, generalised geometry and its relation to
non-geometric backgrounds are explained and compactifications of string theory
with geometric and non-geometric fluxes are discussed. Furthermore covered are
doubled geometry as well as non-commutative and non-associative structures in
the context of non-geometric backgrounds.

33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin