Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Instability and non-uniqueness in the Cauchy problem for the Euler
  equations of an ideal incompressible fluid. Part I   In Part I of the paper, we prove non-uniqueness of the solution to the Cauchy
problem of the Euler equations of an ideal incompressible fluid in dimension
two with vorticity in some Lebesgue space. The radially symmetric external
force is locally integrable with values in the same Lebesgue space.

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The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
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The categories of this paper are: q-fin
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The categories of this paper are: comp-gas
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The categories of this paper are: patt-sol
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The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
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The categories of this paper are: econ
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The categories of this paper are: atom-ph
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The categories of this paper are: funct-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: plasm-ph
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The categories of this paper are: solv-int