Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Null Condition and Global Existence for Nonlinear Wave Equations on
  Slowly Rotating Kerr Spacetimes   We study a semilinear equation with derivatives satisfying a null condition
on slowly rotating Kerr spacetimes. We prove that given sufficiently small
initial data, the solution exists globally in time and decays with a
quantitative rate to the trivial solution. The proof uses the robust vector
field method. It makes use of the decay properties of the linear wave equation
on Kerr spacetime, in particular the improved decay rates in the region
$\{r\leq \frac{t}{4}\}$.

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The categories of this paper are: acc-phys
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The categories of this paper are: stat
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The categories of this paper are: q-fin
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The categories of this paper are: chem-ph
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The categories of this paper are: adap-org
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-lat
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The categories of this paper are: astro-ph
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The categories of this paper are: nlin
3
The categories of this paper are: physics
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The categories of this paper are: atom-ph
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The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
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The categories of this paper are: eess
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-ex