Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Positive Solution of Singular BVPs for System of Dynamic Equations on
  Time Scales   This paper is devoted to derive some necessary and suficient conditions for
the existence of positive solutions to a singular second order system of
dynamic equations with Dirichlet boundary conditions. The results are obtained
by employing the fixed-point theorems and the method of the lower and upper
solutions.

20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
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The categories of this paper are: q-alg
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The categories of this paper are: solv-int
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The categories of this paper are: patt-sol
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The categories of this paper are: bayes-an
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The categories of this paper are: dg-ga
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: nlin
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The categories of this paper are: chem-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: funct-an
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The categories of this paper are: econ
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The categories of this paper are: eess
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The categories of this paper are: math-ph