Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Metric and coupling reversal in string theory   Invariance under reversing the sign of the metric G_{MN}(x) and/or the sign
of the string coupling field H(x), where <H(x)> = g_s, leads to four possible
Universes denoted 1,I,J,K according as (G,H) goes to (G,H), (-G,H), (-G,-H),
(G,-H), respectively. Universe 1 is described by conventional string/M theory
and contains all M, D, F and NS branes. Universe I contains only D(-1), D3 and
D7. Universe J contains only D1, D5, D9 and Type I. Universe K contains only F1
and NS5 of IIB and Heterotic SO(32).

31
The categories of this paper are: ao-sci
18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
3
The categories of this paper are: physics
26
The categories of this paper are: bayes-an
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio