Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Non-Singular String-Cosmologies From Exact Conformal Field Theories   Non-singular two and three dimensional string cosmologies are constructed
using the exact conformal field theories corresponding to SO(2,1)/SO(1,1) and
SO(2,2)/SO(2,1). {\it All} semi-classical curvature singularities are canceled
in the exact theories for both of these cosets, but some new quantum curvature
singularities emerge. However, considering different patches of the global
manifolds, allows the construction of non-singular spacetimes with cosmological
interpretation. In both two and three dimensions, we construct non-singular
oscillating cosmologies, non-singular expanding and inflationary cosmologies
including a de Sitter (exponential) stage with positive scalar curvature as
well as non-singular contracting and deflationary cosmologies. Similarities
between the two and three dimensional cases suggest a general picture for
higher dimensional coset cosmologies: Anisotropy seems to be a generic
unavoidable feature, cosmological singularities are generically avoided and it
is possible to construct non-singular cosmologies where some spatial dimensions
are experiencing inflation while the others experience deflation.

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The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
14
The categories of this paper are: math-ph
4
The categories of this paper are: cond-mat
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
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The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci