Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bifurcation of periodic solutions from a ring configuration in the
  vortex and filament problems   This paper gives an analysis of the movement of n+1 almost parallel filaments
or vortices. Starting from a polygonal equilibrium of n vortices with equal
circulation and one vortex at the center of the polygon, we find bifurcation of
periodic solutions. The bifurcation result makes use of the orthogonal degree
in order to prove global bifurcation of periodic solutions depending on the
circulation of the central vortex. In the case of the filament problem these
solutions are periodic traveling waves.

30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc
18
The categories of this paper are: econ
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
0
The categories of this paper are: hep-ph
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
3
The categories of this paper are: physics
29
The categories of this paper are: funct-an