Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Towards Classification of Phase Transitions in Reaction--Diffusion
  Models   Equilibrium phase transitions are associated with rearrangements of minima of
a (Lagrangian) potential. Treatment of non-equilibrium systems requires
doubling of degrees of freedom, which may be often interpreted as a transition
from the ``coordinate'' to the ``phase'' space representation. As a result, one
has to deal with the Hamiltonian formulation of the field theory instead of the
Lagrangian one. We suggest a classification scheme of phase transitions in
reaction-diffusion models based on the topology of the phase portraits of
corresponding Hamiltonians. In models with an absorbing state such a topology
is fully determined by intersecting curves of zero ``energy''. We identify four
families of topologically distinct classes of phase portraits stable upon RG
transformations.

18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
3
The categories of this paper are: physics
27
The categories of this paper are: comp-gas
29
The categories of this paper are: funct-an
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th