Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A phenomenological operator description of interactions between
  populations with applications to migration   We adopt an operatorial method based on the so-called creation, annihilation
and number operators in the description of different systems in which two
populations interact and move in a two-dimensional region. In particular, we
discuss diffusion processes modeled by a quadratic hamiltonian. This general
procedure will be adopted, in particular, in the description of migration
phenomena. With respect to our previous analogous results, we use here
fermionic operators since they automatically implement an upper bound for the
population densities.

14
The categories of this paper are: math-ph
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
26
The categories of this paper are: bayes-an
4
The categories of this paper are: cond-mat
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
18
The categories of this paper are: econ
22
The categories of this paper are: chao-dyn