Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A topological approach to the existence and multiplicity of positive
  solutions of $(p,q)$-Laplacian systems   In this paper we develop a new theory for the existence, localization and
multiplicity of positive solutions for a class of non-variational,quasilinear,
elliptic systems. In order to do this, we provide a fairly general abstract
framework for the existence of fixed points of nonlinear operators acting on
cones that satisfy an inequality of Harnack type. Our methodology relies on
fixed point index theory. We also provide a non-existence result and an example
to illustrate the theory.

3
The categories of this paper are: physics
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
12
The categories of this paper are: nucl-th
9
The categories of this paper are: nlin