Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evolutionary Prisoner's Dilemma Game in Flocks   We investigate an evolutionary prisoner's dilemma game among self-driven
agents, where collective motion of biological flocks is imitated through
averaging directions of neighbors. Depending on the temptation to defect and
the velocity at which agents move, we find that cooperation can not only be
maintained in such a system but there exists an optimal size of interaction
neighborhood, which can induce the maximum cooperation level. When compared
with the case that all agents do not move, cooperation can even be enhanced by
the mobility of individuals, provided that the velocity and the size of
neighborhood are not too large. Besides, we find that the system exhibits
aggregation behavior, and cooperators may coexist with defectors at
equilibrium.

13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
5
The categories of this paper are: gr-qc
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th