Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exact results for a simple epidemic model on a directed network:
  Explorations of a system in a non-equilibrium steady state   Motivated by fundamental issues in non-equilibrium statistical mechanics
(NESM), we study the venerable susceptible-infected (SIS) model of disease
spreading in an idealized, simple setting. Using Monte Carlo and analytic
techniques, we consider a fully connected, uni-directional network of odd
number of nodes, each having an equal number of in- and out-degrees. With the
standard SIS dynamics at high infection rates, this system settles into an
active non-equilibrium steady state. We find the exact probability distribution
and explore its implications for NESM, such as the presence of persistent
probability currents.

30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
6
The categories of this paper are: astro-ph
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin