Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exotic n-d'Alembert PDE's and Stability   In the framework of the PDE's algebraic topology, previously introduced by A.
Pr\'astaro, {\em exotic $n$-d'Alembert PDE's} are considered. These are
$n$-d'Alembert PDE's, $(d'A)_n$, admitting Cauchy manifolds $N\subset (d'A)_n$
identifiable with exotic spheres, or such that $\partial N$, can be exotic
spheres. For such equations local and global existence theorems and stability
theorems are obtained.

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The categories of this paper are: adap-org
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The categories of this paper are: q-bio
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The categories of this paper are: cmp-lg
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The categories of this paper are: comp-gas
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-lat
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The categories of this paper are: math-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: plasm-ph
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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: chao-dyn
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The categories of this paper are: solv-int
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The categories of this paper are: econ
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The categories of this paper are: astro-ph
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The categories of this paper are: bayes-an