Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A topological degree theory for rotating solutions of planar systems   We present a generalized notion of degree for rotating solutions of planar
systems. We prove a formula for the relation of such degree with the classical
use of Brouwer's degree and obtain a twist theorem for the existence of
periodic solutions, which is complementary to the Poincar\'e-Birkhoff Theorem.
Some applications to asymptotically linear and superlinear differential
equations are discussed.

19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
36
The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
30
The categories of this paper are: q-alg
9
The categories of this paper are: nlin
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The categories of this paper are: adap-org
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The categories of this paper are: astro-ph
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat