Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The instability of followers and emergent vorticity in flocking
  behaviour for an experimental interaction rule   Computational models of collective behavior in birds has allowed us to infer
interaction rules directly from experimental data. Using a generic form of
these rules we explore the collective behavior and emergent dynamics of a
simulated swarm. For a wide range of flock size and interaction extent (the
fixed number of neighbors with which an individual will interact) we find that
the computational collective is inherently stable --- individuals are attracted
to one another and will position themselves a preferred distance from their
fixed neighbors within a rigid lattice. Nonetheless, the irregular overall
shape of the flock, coupled with the need for individuals on the boundary to
move towards their neighbors creates a torque which leads the flock to rotate
and then meander. We argue that this "rolling meander" is a very good proxy for
real collective behavior in animal species and yet arises from a simple
homogeneous and deterministic rule for interaction. Rather than then introduce
leaders --- which has already been shown, quite straightforwardly, to drive
collective swarms such as this --- we introduce a small number of "followers".
Each follower is bound to consider a random fixed individual to be among their
neighbors, irrespective of actual metric distance between them. We find that
the introduction of a small number of such followers causes a phase transition
that quickly leads to instability in the flock structure (as no stable
configuration arises) and the previously rigid crystalline interaction among
neighbors now becomes fluid: the distance between neighbors decreases, the
flock ceases to rotate and meanders less.

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The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
20
The categories of this paper are: acc-phys
23
The categories of this paper are: solv-int
36
The categories of this paper are: cmp-lg
6
The categories of this paper are: astro-ph
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math