Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Accelerating universe without event horizon   It is shown that if a small negative cosmological constant is added to
quintessence models with equation of state $p=\omega\rho$ on the range $-1
<\omega < -1/3$, the resulting scenarios could not contain any future event
horizons. Therefore, such cosmological accelerating scenarios could not present
the kind of obstacles recently pointed out to define a set of observable
quantities analogous to an S-matrix needed by predictive M and string theories
in an accelerating universe driven by dark energy. These scenarios become
accelerating only at early times after coincidence time, and lead finally to
re-collapse.

35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
28
The categories of this paper are: alg-geom
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
25
The categories of this paper are: patt-sol